nvent 910 Maintenance Manual

910 Series Heat Trace Controller

Installation, Operating and Maintenance Instructions

Firmware versions up to V3.1x

Contents

Certication ........................................................................................................................................ 4

Limited Warranty ................................................................................................................................ 4

Warranty Exclusion/Disclaimer ......................................................................................................... 4

Exclusive Remedies ........................................................................................................................... 4

Conducted and Radiated Emissions—FCC/DOC Statement of Compliance ................................. 4

Section 1—Overview .................................................................................................................................. 5

1.1 Introduction .................................................................................................................................. 5

1.2 Controllers Covered by this Manual ........................................................................................... 5

1.3 Product Overview ......................................................................................................................... 5

1.4 Modular Components .................................................................................................................. 6

1.5 Controller Assemblies ................................................................................................................. 7

1.6 Ordering and Conguration Guide .............................................................................................. 7

Section 2—Installation and Wiring............................................................................................................. 9

2.1 Introduction .................................................................................................................................. 9

2.2 Initial Inspection .......................................................................................................................... 9

2.3 Operator Safety Considerations..................................................................................................9

2.4 Operating Environment ................................................................................................................ 9

2.5 Installation Location .................................................................................................................... 9

2.6 Mounting Procedures ................................................................................................................ 10

2.7 Wiring ......................................................................................................................................... 10

2.8 Initial Power-up .......................................................................................................................... 13

2.9 Setup for the 910 ....................................................................................................................... 13

Section 3—Operator Console and Operation ........................................................................................... 14

3.1 Alphanumeric Display ................................................................................................................ 14

3.2 Keypad ........................................................................................................................................ 14

3.3 LED Indicators ............................................................................................................................ 15

3.4 Operational Basics ..................................................................................................................... 15

Section 4—Operator Console Modes ....................................................................................................... 18

4.1 Alarm Mode................................................................................................................................ 18

4.2 Monitor Mode ............................................................................................................................ 19

4.3 Congure Mode ......................................................................................................................... 20

Section 5—Conguration Parameter Details ........................................................................................... 26

5.1 Introduction ................................................................................................................................ 26

5.2 Point Setup Parameters ............................................................................................................ 26

5.3 Miscellaneous Setup Parameters .............................................................................................33

5.4 Temperature Sensor Alarms Conguration .............................................................................34

5.5 Other Alarms Conguration ...................................................................................................... 37

5.6 Communications Setup ............................................................................................................. 44

5.7 Operator Console Functions ..................................................................................................... 46

Section 6—Monitored Parameter Details ................................................................................................ 48

6.1 Introduction ................................................................................................................................ 48

6.2 Analog Readings ........................................................................................................................ 48

6.3 Maintenance Data ..................................................................................................................... 49

Section 7—Control Modes ....................................................................................................................... 51

7.1 Introduction ................................................................................................................................ 51

7.2 Switch Control Modes ............................................................................................................... 51

7.3 Load Shedding Control Mode ................................................................................................... 53

Section 8—Troubleshooting .................................................................................................................... 54

8.1 Operator Checks ........................................................................................................................ 54

8.2 Common Problem Areas ........................................................................................................... 54

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8.3 Common Alarms—What to Look for ......................................................................................... 56

Section 9—Maintenance .......................................................................................................... 60

9.1 Operator Maintenance ...............................................................................................................60

9.2 Replaceable Parts ...................................................................................................................... 60

Appendix A—Specications .................................................................................................................... 61

Appendix B—Typical Enclosure Dimensions ........................................................................................... 62

B.1 Standard Fiberglass EMR Assembly #10170-001 ...................................................................62

B.2 Optional Stainless Steel EMR Assembly #10170-003 ............................................................ 63

B.3 Standard Fiberglass SSR Assembly #10170-0002 .................................................................64

B.4 Optional Stainless Steel SSR Assembly #10170-004 ............................................................. 65

B.5 910 Series HTC Control Module Dimensions .......................................................................... 66

Appendix C—Wiring Diagrams ................................................................................................................. 67

C.1 TS Wiring .................................................................................................................................... 67

C.2 Power Wiring ............................................................................................................................. 67

C.4 Alarm Output Wiring .................................................................................................................. 68

C.5 External Input/Output Port Wiring ............................................................................................ 70

Appendix D—HTC Load Shedding Sequence ........................................................................................... 71

Appendix E—100 Ω Platinum RTD Table .................................................................................................. 72

DIN 43760—100 Ω Platinum Resistance Temperature (RTD)—0.00385 Ohms/Ohm/°C .............72

Appendix F—100 Ω Nickel-Iron RTD Table ............................................................................................... 73

Appendix G—Factory Default Conguration V3.1X.................................................................................. 74

910 Series HTC ................................................................................................................................74

nVent.com | 3

NVENT RAYCHEM 910 SERIES HEAT TRACE CONTROLLER

Installation and Maintenance Instructions for Firmware Versions up to and Including V3.1X
Notice: The information contained in this document is subject to change without notice.

CERTIFICATION

nVent certifies that this product met its published specifications at the time of shipment from
the Factory.

LIMITED WARRANTY

This nVent product is warranted against defects in material and workmanship for a period of
18 months from the date of installation or 24 months from the date of purchase, whichever
occurs first. During the warranty period, nVent will, at its option, either repair or replace
products that prove to be defective.

For warranty service or repair, this product must be returned to a service facility designated by
nVent. The Buyer shall prepay shipping charges to nVent and nVent shall pay shipping charges
to return the product to the Buyer. However, the Buyer shall pay all shipping charges, duties,
and taxes for products returned to nVent from another country.

nVent warrants that the software and firmware designated by nVent for use with the RAYCHEM
910 Controller will execute its programming instructions properly. nVent does not warrant that
the operation of the hardware, or software, or firmware will be uninterrupted or error-free.

WARRANTY EXCLUSION/DISCLAIMER

The foregoing warranty shall not apply to defects resulting from improper or inadequate
maintenance by the Buyer, Buyer-supplied software or interfacing, unauthorized modification
or misuse, operation outside of the specifications for the product, or improper installation.

No other warranty is expressed or implied. nVent disclaims the implied warranties of
merchantability and fitness for a particular purpose.

EXCLUSIVE REMEDIES

The remedies provided herein are the buyer’s sole and exclusive remedies. nVent shall not be
liable for any direct, indirect, special, incidental, or consequential damages, whether based on
contract, tort, or any other legal theory.

CONDUCTED AND RADIATED EMISSIONS—FCC/DOC STATEMENT OF COMPLIANCE

This equipment has been tested and found to comply with the limits for a Class A digital
device, pursuant to Part 15 of the FCC rules. These limits are designed to provide reason- able
protection against harmful interference when the equipment is operated in a commercial
environment. This equipment generates, uses, and can radiate radio frequency energy and,
if not installed and used in accordance with the instruction manual, may cause harmful
interference to radio communications. Operation of this equipment in a residential area is
likely to cause harmful interference, in which case the user will be required to correct the
interference at his own expense.

This equipment does not exceed Class A limits for radio emissions as set out in Schedule V
to VIII of the Radio Interference Regulations of Communication Canada.
Cet apparel respecte les limites de bruits radioelectriques applicables aux appareils numeriques

de Classe A prescrites dans la norme sur le materiel brouilleur: “Appareils Numeriques,”
NMB-003 edictee par le Ministre des Communications.

IMPORTANT WARNINGS AND NOTES

The following icons are used extensively throughout this manual to alert you to important
warnings
the unit.

Be sure to read and follow them carefully.

that affect safety and to important notes that affect the proper operation of

4 | nVent.com

SECTION 1—OVERVIEW

1.1 INTRODUCTION

This manual provides information pertaining to the installation, operation, testing, adjustment,
and maintenance of the nVent RAYCHEM Model 910 Series Heat Tracing Controller.

Additional copies of this user manual may be ordered separately through your nVent
representative or online at nVent.com using the document number H56873.

1.2 CONTROLLERS COVERED BY THIS MANUAL

This document covers the 910 Series Heat Trace Controllers and its available options. The
information coincides with the specific releases of firmware for the 910 product which are
listed on the front page. As nVent releases new firmware to modify or enhance the product
significantly, new documentation will accompany these releases. To ensure that you are using
the correct documentation for your particular version of controller, please check the firmware
version number of the 910 against the version number listed on the front of this manual. This
may be displayed using the Operator Console or a communicating device. As subsequent
changes are made, supplements to this document will be issued and included in manuals
shipped after the firmware is released. Supplements will make specific reference to the
operational or functional changes, and are available at nVent.com.

1.3 PRODUCT OVERVIEW

1.3.1 DESCRIPTION

The 910 Series electronic Heat Tracing Controller controls, monitors, and communicates
alarms and data for one heating circuit. The ability to install the units in Class 1, Division 2
areas supports direct field installation, if desired. It is available with a solid-state relay (SSR)
output for use in hazardous areas or with electromechanical relay (EMR) output for use in
ordinary (non-hazardous) areas.

1.3.2 FEATURES

A detailed description of available features may be found in Section V of this manual.
Highlights of specific features follow.

Keypad and Alphanumeric Display

A six character alphanumeric LED display provides the operator with large easy to read mes­sages and prompts, eliminating complex and cryptic programming. Six individual keys are
provided to quickly access alarming and operational information.

–40°F to 140°F (–40°C to 60°C) Operation

Extended temperature operation permits installation in all but the harshest environments.

Single or Dual Temperature Sensor Inputs

The ability to utilize one or two temperature sensor (TS) inputs allows the selection of one of
eight control modes and programming of all temperature parameters.

High and Low Temperature Alarms

High and low temperature alarms are offered for both temperature sensor inputs of each control
point.

High and Low Current Alarms

The 910 offers full adjustment of both the high and low alarm points over the entire current
measurement range.

Solid State or Electromechanical Relay (EMR) Output

The 910 is available with either a solid-state relay (SSR) or an electromechanical relay (EMR)
output switch. With the SSR option, the user may select a time-proportional control algorithm,
a simple deadband control mode, or one of two ambient control algorithms. The EMR version
always uses either the deadband mode or the proportional ambient contactor mode. Switching
device failure alarms are supported for both types of output devices.

nVent.com | 5

Ground Fault Alarm and Trip

Ground Fault (GF) current levels are monitored and may be displayed in milliamps.
The availability of the actual ground fault level gives the user the choice of both alarm and trip
levels suitable for the particular installation.

Overcurrent Protection

A unique overcurrent protection algorithm greatly reduces the possibility of damage to the
circuit or the controller in the event of a temporary overload while allowing for initially high
in-rush currents (SSR options only).

Soft Starting

Given the circuit breaker size, the 910 will limit the energy let-through to help prevent nuisance
breaker trips due to cable in-rush. This feature makes the controller particularly attractive for
use with self-regulating cables (SSR options only).

Minimum/Maximum Temperature Tracking

The controller maintains the minimum and maximum temperature values it has measured
since the last reset of these values. This is helpful in determining causes of temperature
alarms.

Latching/Non-Latching Temperature Alarms

User selectable non-latching temperature alarms allow the controller to automatically clear the
alarm when the condition no longer exists.

High and Low Voltage Alarms

Operating at voltages less than design can cause serious loss of heater output. The alarming
of preset voltage deviations ensures availability of sufficient wattage output.

Power-Limiting

The 910 will control the maximum output wattage if the full load power exceeds the specified
Maximum Power Setpoint. This feature eliminates the need for low voltage transformers in
many applications and can assist in standardization of heating cable types (SSR options only).

Autocycling

The controller will momentarily energize the circuit (for 10 seconds) at a programmable
interval. Circuit alarms will be generated at the time of autocycle instead of when the heat is
required. This feature eliminates the need for a preventive maintenance program as these tests
are performed at regular intervals by the controller.

Temperature Sensor Failure Alarm

Both open and shorted sensors are detected and alarmed by the controller.

Random Start

A startup delay between 0 and 9 seconds ensures that all units do not come on line at the
same time.

Full Digital Communications

An optional internal communications interface allows the communication of alarms
and analog data to a monitoring system. Industry-standard RS-232 or RS-485 serial
communications are available for applications requiring direct interfacing to other devices.
The modem version maintains compatibility with legacy products, including the Group
Communications Controller (Model 780/GCC-9000). With heat trace data at the user’s
fingertips, historical trending of temperatures, power consumption, or other parameters are
available for analysis and system optimization.

CSA C/US

The 910 Series of controllers are approved for Class I, Division 2, Groups A, B, C, D hazardous
locations making them ideal for direct installation in the field. This may save the significant
expense of wiring back to a centrally located electrical distribution center.

1.4 MODULAR COMPONENTS

The 910 Series controller is made up of two components. Each component’s primary function
is described below.

1.4.1 CONTROL MODULE

The 910 Control Module forms the heart of a single heat trace control solution. Each Control
Module provides all of the intelligence required to control and monitor one heat trace circuit.

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1.5 CONTROLLER ASSEMBLIES

It includes indicators for alarm and output status and an integral Operator Console. An internal
connector is provided to plug in an optional communications interface.

The Control Module packaging provides a rugged, vibration-proof design.
Temperature sensor, communications, and alarm control wiring are connected to the

lever-operated spring terminals, providing gas-tight, vibration-resistant connections.
A large, easy-to-read alphanumeric display and menu-driven interface eases controller

con- figuration and eliminates the need for an external programmer. Access is available for
all monitored parameters, programmed values, and alarm information. Enhanced security is
provided by password protection.

Single phase current monitoring, ground fault detection, and voltage monitoring are provided.
The nVent RAYCHEM 910 Control Module also incorporates a universal power supply, allowing
operation directly from 100 to 277 Vac.

1.4.2 COMMUNICATIONS INTERFACE

In applications where the user wishes remote configuration capability, or wants to
communicate trace information and/or alarms to another device such as a Group
Communications Controller (780 Series/GCC-9000), an optional communications interface
may be installed in the Control Module.

A modem version that maintains compatibility with legacy products is available, or other
industry-standard interfaces such as nVent RAYCHEM RS-232 and RS-485 may be specified.

Two standard assemblies are available and stocked at the Factory:

1. An SSR version for use in ordinary or Class I, Division 2 areas

2. An EMR version for use in ordinary locations only

1.6 ORDERING AND CONFIGURATION GUIDE

NVENT RAYCHEM 910 CONTROLLERS – FACTORY INVENTORY

Description Catalog Number Part Number Weight

RAYCHEM 910 controller in an 8” x 10” FRP enclosure with
window. 2-pole 30 A EMR. Controls a single circuit with a
2-pole electromechanical relay.

(Approved for ordinary areas only)

RAYCHEM 910 controller in an 8” x 10” FRP enclosure with
window. 2-pole 30 A EMR. Controls a single circuit with a
2-pole electromechanical relay.

Includes an isolated 2-wire RS-485 communication option.
(Approved for ordinary areas only)

RAYCHEM 910 controller in an 8” x 10” FRP enclosure with
window. 2-pole 30 A 277 V SSR. Controls a single circuit with
a 2-pole solid-state relay.

(Approved for Class I, Div. 2 areas)

RAYCHEM 910 controller in an 8” x 10” FRP enclosure with
window. 2-pole 30 A 277 V SSR. Controls a single circuit with
a 2-pole solid-state relay. Includes an isolated 2-wire RS-485
communication option. (Approved for Class I, Div. 2 areas)

nVent RAYCHEM Supervisor Software RAYCHEM Supervisor 10391-002 1

910*E1FWL*EMR2 10170-001 15

910*E1FWL*EMR2*485 10170-015 15

910*E1FWL*SSR2 10170-002 20

910*E1FWL*SSR2*485 10170-016 20

RAYCHEM 910 CONTROLLERS – MADE-TO-ORDER (Contact factory for lead time)

nVent.com | 7

RAYCHEM 910 controller in an 8” x 10” stainless-steel
enclosure with window. 2-pole 30 A EMR. Controls a single
circuit with a 2-pole electromechanical relay.
(Approved for ordinary areas only)

RAYCHEM 910 controller in an 8” x 10” stainless-steel
enclosure with window. 2-pole 30 A EMR. Controls a single
circuit with a 2-pole electromechanical relay. Includes an
isolated 2-wire RS-485 communication option.
(Approved for ordinary areas only)

RAYCHEM 910 controller in an 8” x 10” stainless-steel
enclosure with window. 2-pole 30 A 277 V SSR. Controls a
single circuit with a 2-pole solid-state relay.
(Approved for Class I, Div. 2 areas)

RAYCHEM 910 controller in an 8” x 10” stainless-steel
enclosure with window. 2-pole 30 A 277 V SSR. Controls a
single circuit with a 2-pole electromechanical relay. Includes
an isolated 2-wire RS-485 communication option.
(Approved for Class I, Div. 2 areas)

RTD SENSORS

910*E1SW*EMR2 10170-003 20

910*E1SW*EMR2*485 10170-017 20

910*E1SW*SSR2 10170-004 25

910*E1SW*SSR2*485 10170-018 25

100-ohm platinum RTD with 10’ stainless-steel corrugated

RTD10CS RTD10CS 1.0

sheath

RTD, ambient, cable style MONI-RTD-200 254741 0.1

C1D1 RTD, –100°F to 900°F, pipe mounted RTD7AL RTD7AL 2.0

RTD, –100°F to 900°F, pipe mounted RTD4AL RTD4AL 1.2

OPTIONS

Append the following code(s) to the end of the standard Model Code to have the option
included at the factory

Option Code Description

*232

*MDM

*ALR
*ALG

RS-232 communications option (replace *485 with *232)
Modem communications option (replace *485 with *MDM)

Red LED pilot light
Green LED pilot light

Contact your local representative for configurations not listed here.

8 | nVent.com

SECTION 2—INSTALLATION AND WIRING

Caution: Be sure all personnel involved in installation, servicing, and programming are qualified
and familiar with electrical equipment, their ratings and proper practices and codes. Multiple
voltages and signal levels may be present during the installation, operation, and servicing of
this product. Do not power the product until the safety provisions outlined in this section have
been observed.

2.1 INTRODUCTION

This section includes information regarding the initial inspection, preparation for use, and
storage instructions for the 910 Series Heat Trace Controller.

2.2 INITIAL INSPECTION

Inspect the shipping container for damage. If the shipping container or cushioning material
is damaged, it should be kept until the contents of the shipment have been verified for com­pleteness and the equipment has been checked mechanically and electrically. Procedures

for configuring and operating the heat trace controller are given in Sections III, IV, and V. If
the shipment is incomplete, there is mechanical damage, a defect, or the controller does not
pass the electrical performance tests, notify the nearest nVent representative. If the shipping
container is damaged, or the cushioning material shows signs of stress, notify the carrier as
well as your nVent representative. Keep the shipping materials for the carrier’s inspection.

2.3 OPERATOR SAFETY CONSIDERATIONS

The standard 910 controller using solid-state relays is suitable for Class 1, Division 2, Groups
A, B, C, and D hazardous areas. Hazardous areas are defined by Article 500 of the National
Electrical Code and Section 18 of the Canadian Electrical Code. Electromechanical relay (EMR)
based assemblies are suitable for use in ordinary (non-hazardous) areas only.

Caution: Some wiring configurations will use more than one power source and all must be
de-energized prior to performing any maintenance on a controller circuit.

2.4 OPERATING ENVIRONMENT

2.5 INSTALLATION LOCATION

2.6 MOUNTING PROCEDURES

The operating environment should be within the limitations specified in the 910 Heat Trace
Controller Specifications outlined in Appendix A.

The wide ambient operating temperature range of the controller permits installation in most
any convenient location. Considerations should include expected atmospheric conditions,
accessibility for maintenance and testing, the location of existing conduits and hazardous area
rating. Ambient temperature conditions may affect load current ratings.

Caution: Always be sure that the intended location is classified as an area that the product is
approved for as defined by Article 500 of the National Electrical Code and/or Part I, Section 18
of the Canadian Electrical Code.

Mounting hole dimensions for the standard enclosures are shown in Appendix B. Conduit
entries should be made in the bottom of the enclosure if possible to reduce the possibility
of water entry or leakage. Conduit entries must be drilled/punched following the enclosure
manufacturers’ recommendations. Use bushings suitable for the enclosure type and install
such that the completed installation remains waterproof. For nonmetallic enclosures,
grounding hubs and conductors must be installed in accordance with Article 501-4(b)
of the National Electrical Code and Part I of the Canadian Electrical Code.

nVent.com | 9

The user may want to consider enclosure drain holes in applications where moisture is a

Communications inter

communications, inhibit/override

problem; drill 0.125” holes in the bottom of the enclosure on both the left and right sides.
Two holes reduce the possibility that one will plug and ensures drainage if the enclosure is not
perfectly level. Note that drilling holes in the enclosure compromises the NEMA 4 rating.

2.6.1 Controller Installation and Removal

CAUTION:

Always ensure that the power to the unit is turned off during installation or removal to avoid
the risk of injury and damage to the controllers.

WARNING:

Explosion Hazard! Do not install or remove the control module while the unit is powered.

HTCBus communications address

D910 SERIES

Communications status indicators

Alarm status indicator
Output status indicator

2.7 WIRING

type label (optional)

face

L1/Line in

L2/Neutral in

L1/Line out to tracer

L2/Neutral out to tracer

RTD,
input, alarm dry contact output

D910-010

AC alarm output

Fig. 2.1 Control module face

Wiring diagrams for typical configurations are included in Appendix C of this manual.

CAUTION:

Always verify wiring connections before applying power to the controller or connected circuits.
To avoid injury or equipment damage, do not install or remove wiring while controller power is
on. To minimize the chance of loose connections, the 910 uses lever-operated, spring-loaded
terminals for signal wiring. See Appendix A for allowable wire sizes and recommended
insu- lation strip lengths.

2.7.1 TEMPERATURE SENSOR CONNECTIONS

Use shielded, twisted, three-conductor wire for the extension of RTD leads. The wire size
should ensure that the maximum allowable lead resistance is not exceeded. Shields on RTD
wiring should be grounded at the controller end only, using the terminals provided.

Temperature Sensors Terminal No.

Shield 19

TS 1 Source (WHT) 20

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S 1 Sense (WHT) 21

TS 1 Common (RED) 22

Shield 8

TS 2 Source (WHT) 9

TS 2 Sense (WHT) 10

TS 2 Common (RED) 11

2.7.2 ALARM RELAY CONNECTIONS

Two types of alarm relays are provided: one is a programmable dry contact output relay and
the other is a line voltage AC relay (Triac). Both may be programmed for N.O., N.C., steady or
flashing operation, and are typically used to annunciate an alarm to an external device such as
a DCS, PLC, etc.

Notes:

• Both alarm relays are controlled by the 910 using the same signal. The N.O., N.C., and
flashing parameter settings affect both the dry contact and the AC alarm relays.

• The dry contact alarm relay is intended to be used for switching low-voltage, low-current
signals. Do not use this relay to directly switch line voltages. Ensure that your application
stays within the ratings of the relay contacts as defined in Appendix A.

The AC alarm relay alarm relay is typically used to drive a local, external, line-voltage pilot light,
etc. Refer to the wiring diagrams in Appendix C for example connection details.

Dry Contact Alarm and Control Signals Terminal No.

Alarm relay dry contact output 14

Alarm relay dry contact output 15

Ground 4

+12Vdc nom. Out 3

AC Alarm and Control Signals Terminal No.

L1/Line out 1

L2/Neutral out 2

AC alarm relay 12

AC alarm relay 13

2.7.3 EXTERNAL CONTACT INPUT/OUTPUT

These input terminals are used to implement the inhibit and override features.
Refer to Section V of this manual for programming details, and Appendix C for example
wiring diagrams.

Miscellaneous Signals Terminal No.

External input (+) 6

External input (-) 7

2.7.4 COMMUNICATION SIGNAL CONNECTIONS

The communications terminal assignments change based on the type of option installed.
Ifpresent in a 910 Control Module, the type of communications interface will be identified by a
label located on the front of the control module (Figure 2.1).

Communications wiring should use nVent RAYCHEM twisted pair, shielded cable. Shields on
communications wiring should be grounded at one end only, using the terminals provided.

nVent.com | 11

The following tables define the appropriate signal connections for the various types of interfaces:

RS-485 (2-Wire) Connections

Communication Signal Terminal No.

Receive/transmit data (+) 16

Receive/transmit data (-) 17

Shield 18

RS-232 (3-Wire) Connections

Communication Signal Terminal No.

Receive data 16

Transmit data 17

Common 18

Modem Interface Connections

Communication Signal Terminal No.

Modem 16

Modem 17

Shield 18

2.7.5 POWER CONNECTIONS

All of the power terminals are labeled for easy identification. Do not attempt to use wire sizes
that exceed the marked terminal ratings and avoid terminating two wires on the same terminal
whenever possible.

Always be sure that all terminals are adequately tightened according to the terminal
manu- facturer’s specification. See Appendix A for allowable wire sizes, recommended
insulation strip lengths, and tightening torque. A loose terminal can cause arcing and damage
to the terminal or incorrect operation of the controller.

IMPORTANT: Make sure that power terminals are retightened several days after installation.
Stranded wire will tend to compress when initially installed; therefore, these terminals should
be checked for tightness several times after the system is installed to ensure that a good
connection is maintained. Be certain to use the proper size screwdriver for the terminal blocks
to minimize the chance of damage to the terminals.

If the controllers are installed in either a metallic or non-metallic enclosure, follow the
enclosure manufacturer’s recommendations for proper grounding. Do not rely on conduit
connections to provide a suitable ground.

Grounding terminals/screws are provided for connection of system ground leads. Proper
system grounding is required for safe and correct operation of the controller’s protection
features.

2.7.6 INPUT POWER

The 910 controller may be powered directly from a 100 to 277 Vac circuit. The wiring terminal
assignments are defined below.

Power Connections Terminal No.

Line/L1 power input A

Neutral/L2 power input B

Line/L1 output to trace C

Neutral/L2 output to trace D

Wiring diagrams for typical configurations are included in Appendix C.

Many wiring configurations will use more than one power source and all must be de-energized
prior to performing any maintenance on a controller circuit.

12 | nVent.com

CAUTION:

2.8 INITIAL POWER-UP

2.9 SETUP FOR THE 910

CAUTION:

Before applying power to the controller, ensure that powering the circuit will not damage it if
power limiting or the setpoint temperature have not been set correctly. If there is any doubt, the
load should be disconnected until the 910 has been suitably programmed for correct and safe
operation.

2.8.1 INITIAL CABLE TEST

To minimize the risk of damage to the controller due to a cable fault, the integrity of the
heating cable should be verified by:

1. Performing a high voltage insulation test using a “Megger”

2. Using an ohmmeter to ensure that the heating cable is not shorted

These tests must be performed with the controller output disconnected.
Once the cable has been checked, it may be reconnected to the controller and power applied.

2.8.2 RANDOM START DELAY

All 910 Series Control Modules incorporate a RANDOM START-UP DELAY feature, ensuring that
all units do not power on at the same time. When power is first applied to a controller, it will
hold its output off for a random time (0 to 9 seconds), equal to the last digit of the HTCBUS™
communications address (see Section 5.6.2). Once the start-up delay has timed out, the
controller will begin normal operation.

The 910 may be programmed using the Operator Console, or if a communications option is
installed, with an external communicating device. For instructions on the operation of these
devices, refer to the corresponding operating manuals. For complete instructions on pro­gramming the 910, see the Programming and Configuration Section of this manual.

nVent.com | 13

SECTION 3—OPERATOR CONSOLE AND OPERATION

3.1 ALPHANUMERIC DISPLAY

The console incorporates a six character, fourteen segment plus decimal LED display.
Messages and prompts that are greater than six characters long are scrolled, allowing more
meaningful, non-cryptic messages to be used.

3.2 KEYPAD

The local keypad consists of six keys that allow you to select the console mode function that
you are interested in. For certain keys, the SHIFT key selects an alternate function, as shown by
the text above that key.

Key Function

SHIFT • Press to activate a SHIFTed function; the next key pressed

TEST [shift ALARM] • Turns on tracing for 30 seconds

◃ BACK [shift MONITOR]

▹ ENTER [shift CONFIG] • Selects the item in the display (or accepts the setting when

▵

▿

uses the alternate (shifted) function

• The SHIFT LED illuminates, indicating the next key uses
thealternate (shifted) function

• Pressing SHIFT again cancels the alternate
(shifted) function

• When prefixed by the SHIFT key, this key switches the
console to the Alarm mode

• Exits the current menu (or cancels the new setting when
editing aparameter)

• Moves the cursor to the left when editing an
alphanumeric parameter

• When prefixed by the SHIFT key, this key switches the
console to the Monitor mode

editing a parameter)

• Moves the cursor to the right when editing an alphanumeric
parameter

• When prefixed by the SHIFT key, this key switches the
console to the Configure mode

• Moves to the previous item in a menu

• Increments the value when editing

• Moves to the next item in a menu

• Decrements the value when editing

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3.3 LED INDICATORS

3.4 OPERATIONAL BASICS

The console includes eight LED indicators:
Four LEDs indicate the console operating mode (SHIFTed function, ALARM, MONITOR, or
CONFIGure modes).
There are two status LEDs which indicate the alarm and control output status of the controller:

1. The output LED, when illuminated steadily, indicates that the output of the controller
is turned on and is allowing current to flow into the loadtrace circuit. For SSR versions
programmed for proportional modes, a flashing LED indicates that the controller is pulsing
its output on and off to maintain the setpoint temperature and/or control the average
amount of current/power the tracer uses.

2. The alarm LED will flash (approximately once per second) when the controller has detected
an alarm condition.

The two additional LEDs are used to indicate external communications activity and are only
used when an optional communications interface is installed. The “Rx” LED flashes to show
that the Controller is receiving information via its communications port. The “Tx” LED flashes
when the Controller is transmitting information via its communications port.

3.4.1 OPERATING MODES

The console operates in one of four modes and is related to the basic function the operator
selects.

Mode Function

Scan This is the default mode. In this mode, the console sequentially displays

load current, temperature, and setpoint readings.

Alarm Invoked when you press the SHIFT key followed by the ALARM key. This

mode allows you to examine or reset any alarms that may exist. The
LED above the ALARM key is illuminated while in this mode.

Monitor Invoked when you press the SHIFT key followed by MONITOR key. In

this mode, you may examine any of the controller readings such as
temperature, load current, etc.
The LED above the MONITOR key is illuminated while in this mode.

Configure Invoked when you press the SHIFT key followed by CONFIG key.

In this mode, you may examine or alter the controller configuration.
The LED above the CONFIG key is illuminated while in this mode

3.4.2 MENUS

Each of the operating modes has a list of data items associated with it. For example, in the
Monitor mode you may view temperatures, load current, resistance, ground fault current,
voltage, or power information. This collection of data items is referred to as a menu.

Only one menu item may be viewed at a time. The ▿
item in the menu. When you reach the end of the menu (indicated by ---- END ---), ▿ wraps you

to the first item in the menu; conversely, ▵ wraps you to the last item in the menu.
Some of the items within a menu are actually entry points to sub-menus—these entries are

indicated with “…” at the end of the message. To enter a sub-menu, press the ▹ key. To move
around in the menu, use the ▿ and ▵ keys move to the next and previous items respectively.
The ◃ key exits the current menu and returns to the previous menu.

( ▵ ) keys move to the next (previous)

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After approximately five minutes of keypad inactivity, the current menu and mode will be
exited and the console will revert to the Scan mode.

IMPORTANT: Some menus are dynamic; that is, some items appear or disappear
depending on the configuration. For example, if you disable the Low Voltage Alarm, then the
corresponding Low Voltage Setpoint is not available and will not be displayed.

3.4.3 CHANGING THE CONFIGURATION

To change the Controller configuration, follow the directions listed below.

• Position the desired parameter (menu item) in the display.

• Press the ▹ key to initiate an edit session.

• If the console is “locked” you are prompted to enter the passcode.

• The present setting will flash on the display to indicate that you are editing the parameter.

• Use the and keys to change the value.

• The operation of the ▹ and varies depends on the type of data being editing. See the

following sections for details.

IMPORTANT: Once you have initiated an edit session, you must end it before switching to
another mode or invoking another function. An edit session ends when you enter a new value
(using the t> key) or you back out of it (using the ◃ key).

3.4.4 CHANGING A NON-NUMERIC PARAMETER

To change a non-numeric parameter (e.g.: an alarm mask setting), follow the directions below.

• Position the appropriate parameter in the display.

• Press the ◃ key to initiate the edit session.

• If the console is “locked” you are prompted to enter the passcode.

• The present setting will flash on the display to indicate that you are editing the parameter.

• Use ▿

• Pressing ▹ saves the new value.

• Pressing ◃ ends the edit session without altering the parameter.

or ▵ until the desired value appears in the display.

3.4.5 CHANGING A NUMERIC PARAMETER

To change a numeric parameter (e.g. the control setpoint), follow the directions below.

• Position the appropriate parameter in the display.

• Press the t> key to initiate the edit session.

• If the console is “locked” you are prompted to enter the passcode.

• The present value is displayed and the last (rightmost) digit blinks.

• The blinking digit identifies the digit that you are editing.

• Use ▿

• Use ◃ or ▹ to move to a different digit.

• To enter a negative value, scroll to the first (leftmost) digit until a “-” appears in the display.

• Pressing ▹ while on the last (rightmost) digit saves the new value.

• Pressing ◃ while on the first (leftmost) digit ends the edit session without altering the

or ▵ to set the desired value.

parameter.

3.4.6 PASSCODE PROTECTION

The 910 Series Controller provides a passcode for protection of its configuration. You may
view any portion of the configuration with the console “locked”; however, when you attempt
to initiate an edit session by pressing ▹, you are prompted to enter the passcode. Entering the
passcode is just like entering any other numeric value; see Section 3.4.5 “Changing a Numeric
Parameter.”

Once the console is “unlocked,” you may edit any configuration parameter. The console will
automatically re-lock after approximately five minutes of keypad inactivity, or until the user
explicitly locks it.

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IMPORTANT:

• Setting the programmed passcode to “0” disables passcode protection.

• The console does not have to be unlocked to reset alarms.

3.4.7 FEATURE MODES

There are two types Configuration Menus in the 910 Series Controller.

1. A “Basic” Configuration Menu which only contains seven parameters

2. An “Advanced” Configuration Menu which contains all of the parameters

Both types of Configuration Menus contain a “Feature Mode” parameter which allows the user
to select which type of Configuration Menu is most desirable.

3.4.8 QUICK NOTES ON OPERATION

Remember the following basic rules for efficient Console use:

• Use the SHIFT key followed by the appropriate function key—ALARM, MONITOR, or
CONFIG—to select the operating mode

• Use ▿

• Use ▹ to enter a new menu, enter a new value, or select a menu item

• Use ◃ to exit the current menu or cancel an edit

and ▵ to move around in the menu

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SECTION 4—OPERATOR CONSOLE MODES

4.1 ALARM MODE

The Alarm mode is invoked when you press the SHIFT key followed by the ALARM key. This
mode allows you to examine and reset any alarms that may exist. Use ▿

next (previous) active alarm.

4.1.1 RESETTING ONE ALARM

To reset an alarm, press ▹. You are prompted for confirmation; answering YES resets the alarm
and advances you to the next alarm.

4.1.2 RESETTING ALL ALARMS

To reset all active alarms, press ▹. You are prompted for confirmation; press to select
ALL and press ▹ to accept.

4.1.3 MONITOR MODE TRACKING

The Monitor mode “tracks” the Alarm mode. If the Monitor mode is selected while viewing an
alarm, the controller will enter the MONITOR menu and display an appropriate reading.

For example, if you are examining a High Load Current Alarm and then select the Monitor
mode, the starting point within the MONITOR menu will be the load current reading. Once the

Monitor mode has been selected, you may move around in the menu using ▿

4.1.4 ALARM MESSAGES

Table 4.1 lists sample alarms and the corresponding starting point in the Monitor mode menu,
if it is invoked from the Alarm mode.

(▵) to examine the

and ▵ .

Table 4.1 Alarm Messages

Sample Alarm Message Monitor Mode Starting Point

LO TS 1 = –2°C TS 1 temperature

HI TS 1 = 102°C TS 1 temperature

TS 1 FAIL = ALARM TS 1 temperature

LO TS 2 = –4°C TS 2 temperature

HI TS 2 = 105°C TS 2 temperature

TS 2 FAIL = ALARM TS 2 temperature

CTL TS FAIL = ALARM Control temperature

LO LOAD = 0.5 A Load current

HI LOAD = 21.0 A Load current

HI GFI = 52 mA Ground fault current

GFI TRIP = 77 mA Ground fault current

LO VOLT = 85 V Voltage

HI VOLT = 140 V Voltage

LO RESIST = 3.38 Ω Resistance

HI RESIST = 9.24 Ω Resistance

OVERCURRENT TRIP = ALARM Load current

SWITCH FAIL = ALARM Load current

HTC RESET = ALARM Time since last reset

SWITCH LIMITING = ALARM Load current

C.B. LIMITING = ALARM Load current

POWER LIMITING = ALARM Power

EEROM DATA FAIL = ALARM n/a

CONTACTOR COUNT = 200000 Contactor cycle count

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4.2 MONITOR MODE

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The Monitor mode is invoked when you press the SHIFT key followed by the MONITOR key.
This mode allows you to test the heat tracing and examine any of the analog readings.

The data is updated in real-time, providing the user with a method of viewing tracer information
as it occurs.

4.2.1 MAIN MENU

Table 4.2 Monitor Mode Main Menu

ONTROL MODE = 4°C

S 1 TEMP = 4°C
S 2 TEMP = 7°C (only if TS2 is being used)

OAD = 8.9 A

ESIST = 13.26 Ω

FI = 0 mA

OLT = 118 V

OWER = 1050 W (or POWER = 10.4 kW)

EST TRACING = (Turn on tracing for 30 seconds)

ISPLAY TEST = (To abort DISPLAY TEST, press any key)

AINTENANCE DATA… = Note the “…” indicating a sub-menu

--- END ----

4.2.2 “MAINTENANCE DATA…” SUB-MENU

This sub-menu is used to view minimum and maximum temperatures, total accumulated
power, hours in use, and the number of hours since the last time the Controller was reset.

These parameters may be reset by the user.

ONTROL TEMP = 4°C

S 1 TEMP = 4°C
S 2 TEMP = 7°C

OAD = 8.9 A

ESIST = 13.26 Ω

FI = 0 mA

OLT = 118 V

OWER = 1050 W

EST TRACING

ISPLAY TEST

AINTENANCE DATA…

---- END ----

Table 4.3 Maintenance Data Sub-Menu

MIN CTL TEMP = –2°C

AX CTL TEMP = 65°C

S 1 MIN TEMP = –2°C

S 1 MAX TEMP = 65°C

S 2 MIN TEMP = –1°C

S 2 MAX TEMP = 61°C

OWER ACCUM = 145.9 kW-h

ONTACTOR CYCLE COUNT = 1234 (only if Deadband or Prop. Amb. Contactor

modes are being used)

N USE = 2896 h

IME SINCE LAST RESET = 675 h

---- END ----

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4.3 CONFIGURE MODE

The Configure mode is selected when the operator presses the SHIFT key followed by the
CONFIG key. This mode allows you to examine or alter the Controller’s configuration. There are
two types of configuration modes each presenting different features: Basic and Advanced.

The Basic Configuration Mode will limit the display to seven of the most commonly modified
parameters, while the Advanced Configuration Mode presents all of the available parameters.
Both Configure mode menus contain a parameter called FEATURE MODE which allows the
user to specify which Configure mode is to be used.

IMPORTANT: All parameters that are enabled are active with their corresponding settings
even if the Basic Configuration Mode is currently active. Selecting the Basic Configure mode of
opera- tion simply hides the display of certain parameters, but does not disable them.

Table 4.4 Basic Configure Mode Menu

CONTROL SETPOINT = {–60 to 570}°C

LO TS 1 = {–60 to 570}°C

LO LOAD = {0.3 to 100.0} A

SWITCH CONTROL MODE = {Proportional, Prop. Amb., SSR, Deadband, or Prop. Amb.

Contactor}

CIRCUIT BREAKER = {0.3 TO 100.0} A (only if SSR is being used)

TEMP UNITS = {°C or °F}

FEATURE MODE = {Basic or Advanced}

LOCK DATABASE = (Only if passcode is not 0 and database is unlocked)

UNLOCK DATABASE = (Only if passcode is not 0 and database is locked)

---- END ----

4.3.2 ADVANCED CONFIGURE MODE MAIN MENU

Menu items with a trailing “...” indicate an entry point to a sub-menu. To enter a sub-menu, use

and ▵ to position the menu item in the display and then press ▹. Note that the controller

▿

“remembers” where you are in the Configure mode if you temporarily switch to a different
mode (such as the Monitor mode). Switching back to the Configure mode will return you to the
same menu item.

MPORTANT: A few of the controller parameters that are often used have been duplicated in
the Advanced Configure mode main menu for quick access. These parameters (Lo TS 1, Lo
Load, Hi GFI, GFI Trip) may also be accessed using their respective sub-menus.

Table 4.5 Advanced Configure Mode Main Menu

CONTROL SETPOINT = {–60 to 570}°C

LO TS 1 = {–60 to 570}°C

LO LOAD = {0.3 to 100.0} A

HI GFI = {20 to 250} mA GFI TRIP = {20 to 250} mA

FEATURE MODE = {Basic or Advanced}

TS ALARMS CONFIG… Note that the menu items with a trailing “…” indicate

the entry point to a sub-menu

OTHER ALARMS CONFIG…

POINT SETUP…

MISC SETUP…

COMMUNICATIONS SETUP…

LOCK DATABASE (Only if passcode is not 0 and database is unlocked

UNLOCK DATABASE (Only if passcode is not 0 and database is locked)

---- END ----

This sub-menu is used to set up alarms that relate to any of the temperature sensors.
Each alarm may be ENAbled or DISabled, and if the alarm is ENAbled, an alarm setting
may be entered.

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4.3.3 “TS ALARMS CONFIG…” SUB-MENU

This sub-menu is used to set up alarms that relate to any of the temperature sensors.
Each alarm may be ENAbled or DISabled, and if the alarm is ENAbled,
an alarm setting may be entered.

ONTROL SETPOINT = 20°C

O TS 1 = –10°C

O LOAD = 1.0 A

I GFI = 50 mA

FI TRIP = 75 mA

S ALARMS CONFIG…

THER ALARMS CONFIG…

OINT SETUP…

MISC SETUP…

OMMUNICATIONS SETUP…

---- END ----

Table 4.6 TS Alarms Configuration Sub-Menu

S 1 FAIL = {ENA or DIS}

O TS 1 = {ENA or DIS}
O TS 1 = {–60 TO 570}°C

I TS 1 = {ENA or DIS}
I TS 1 = {–60 TO 570}°C

S 2 FAIL = {ENA or DIS}

O TS 2 = {ENA or DIS}
O TS 2 = {–60 TO 570}°C

I TS 2 = {ENA or DIS}
I TS 2 = {–60 TO 570}°C

O TS FILTERS = {0 to 999} MIN (only if LO TS 1 or 2 are enabled)

I TS FILTERS = {0 to 999} MIN (only if HI TS 1 or 2 are enabled)

ATCH TS ALARMS = {YES or NO}

TL TS FAIL = {ENA or DIS}

---- END ----

4.3.4 “OTHER ALARMS CONFIG...” SUB-MENU

This sub-menu allows the user to set up all alarms that do not directly relate to the temperature
sensors. These include all AC alarms (voltage, current. ground fault, etc.) as well as protection
settings such as power limiting, etc.

Each alarm may be ENAbled or DISabled. If the alarm is ENAbled, an alarm setting and filter
setting may be entered.

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ONTROL SETPOINT = 20°C

O TS 1 = –10°C

O LOAD = 1.0 A

I GFI = 50 mA

FI TRIP = 75 mA

S ALARMS CONFIG…

THER ALARMS CONFIG…

OINT SETUP…

ISC SETUP…

OMMUNICATIONS SETUP…

---- END ----

Table 4.7 Other Alarms Configuration Sub-Menu

O LOAD = {ENA or DIS}
O LOAD = {0.3 to 100.0} A

O LOAD FILTER = {0 to 12} S

I LOAD = {ENA or DIS}
I LOAD = {0.3 to 100.0} A

I LOAD FILTER = {0 TO 12} S

I GFI = {ENA or DIS}
I GFI = {20 to 250} mA

I GFI FILT ER = {0 to 12} S

FI TRIP = {ENA or DIS}

FI TRIP = {20 to 250} mA
O VOLT = {ENA or DIS}
O VOLT = {10 to 330} V

O VOLT FILTER = {0 to 12} S

I VOLT = {ENA or DIS}
I VOLT = {10 to 330} V

I VOLT FILTER = {0 to 12} S

O RESIST = {ENA or DIS}
O RESIST = {1 to 100} %

O RESIST FILTER = {0 to 12} S

I RESIST = {ENA or DIS}
I RESIST = {1 To 250} %

I RESIST FILTER = {0 to 12) S

OMINAL RESIST = {2.00 to 2000.00} Ω (only if LO or HI is enabled)

VERCURRENT TRIP = {ENA or DIS} (only if SSR is being used)

WITCH FAIL = {ENA or DIS}

TC RESET = {ENA or DIS}

.B. LIMITING = {ENA or DIS} (only if SSR is being used)

OWER LIMITING = {ENA or DIS} (only if SSR is being used)

WITCH LIMITING = {ENA or DIS} (only if SSR is being used)

ONTACTOR COUNT = {ENA or DIS} (only if Deadband or Prop Amb

Contactor are being used)

ONTACTOR COUNT = {0 to 999999} (only if Deadband or Prop Amb

Contactor are being used)

EEROM DATA FAIL = {ENA or DIS}

---- END ----

4.3.5 “POINT SETUP…” SUB-MENU

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The “Point Setup” sub-menu is used to configure parameters that relate directly to the specific
control point. Included in this menu are control mode settings, circuit breaker and switch
ratings, autocycle set-up parameters, etc.

4.3.5 “POINT SETUP…” SUB-MENU

The “Point Setup” sub-menu is used to configure parameters that relate directly to the specific
control point. Included in this menu are control mode settings, circuit breaker and switch
ratings, autocycle set-up parameters, etc.

ONTROL SETPOINT = 20°C

O TS 1 = –10°C

O LOAD = 1.0 A

I GFI = 50 mA

FI TRIP = 75 mA

S ALARMS CONFIG…

THER ALARMS CONFIG…

OINT SETUP…

MISC SETUP…

OMMUNICATIONS SETUP…

---- END ----

Table 4.8 Point Setup Sub-Menu

AG = {19 ALPHANUMERIC CHARACTERS}

WITCH CONTROL MODE = {PROPORTIONAL, PROP AMB SSR, DEADBAND, or

PROP AMB CONTACTOR}

EADBAND = {1 to 50}°C (only if SWITCH CONTROL MODE

is DEADBAND)

ROP BAND = {1 to 50}°C (only if SWITCH CONTROL MODE

is not DEADBAND)

YCLE TIME = {10 to 255} MIN (only if SWITCH CONTROL MODE

is not PROP AMB CONTACTOR)

WITCH RATING = {0.3 to 100.0} A (only if SSR is being used)

IRCUIT BREAKER = {0.3 to 100.00} A (only if SSR is being used)

AX POWER = {3 W to 33,000} W (only if SSR is being used)

S FAIL MODE = {OFF or ON}

S CTL MODE = {TS 1-FAIL OFF (ON) or

TS 1-FAIL TO TS 2 or
TS 2-FAIL OFF (ON) or
TS 2-FAIL TO TS 1 or
AVERAGE-FA IL OFF (ON) or
AVERAGE-FA IL TO GOOD or
LOWEST-FAIL OFF (ON) or
LOWEST-FAIL TO GOOD}

S 1 TYPE = {100 W PLAT or NI-FE}

S 1 LEAD RESIST = {1 to 20.000} Ω (only if TS 1 TYPE = NI-FE)

S 1 HI LIMIT = {ENA or DIS}

S 2 TYPE = {100 W PLAT or NI-FE}

S 2 LEAD RESIST = {0 TO 20.000} Ω (only if TS 2 TYPE = NI-FE)

S 2 HI LIMIT = {ENA or DIS}

UTO-CYCLE = {ENA or DIS}

UTO-CYCLE INTERVAL = {1 to 240} (only if AUTO-CYCLE=ENA)

UTO-CYCLE UNITS = {HOURS or MINUTES} (only if AUTO-CYCLE=ENA)

VERRIDE SOURCE = {REMOTE or EXT INPUT}

OAD SHEDDING = {ENA or DIS}

---- END ----

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4.3.6 “MISC. SETUP…” SUB-MENU

P

COMMUNICA

The “Misc. Setup” sub-menu is used to configure miscellaneous parameters.

CONTROL SETPOINT = 20°C

LO TS 1 = –10°C

LO LOAD = 1.0 A

HI GFI = 50 mA

GFI TRIP = 75 mA

TS ALARMS CONFIG…

OTHER ALARMS CONFIG…

POINT SETUP…

MISC SETUP…

TIONS SETUP…

---- END ----

Table 4.9 Misc. Setup Sub-Menu

TEMP UNITS = {°C or °F}

VERSION = V3.16.3

EXT. INPUT = {NOT USED, INHIBIT or FORCE ON}

FLASH ALARM OUTPUT = {YES or NO}

ALARM OUTPUT = {N.C. or N.O.}

LANGUAGE = {ENGLISH or FRANCAIS}

ASSCODE = {0000 to 9999} (only if 0 or database is unlocked)

SCROLL DELAY = {0.07 to 0.25} S

LOAD DEFAULTS

---- END ----

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4.3.7 “COMMUNICATIONS SETUP...” SUB-MENU

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The settings found in this sub-menu must be configured whenever an optional
communications board is installed in the Control Module.

CONTROL SETPOINT = 20C

LO TS 1 = –10C

LO LOAD = 1.0 A

HI GFI = 50 mA

GFI TRIP = 75 mA

TS ALARMS CONFIG…

OTHER ALARMS CONFIG…

POINT SETUP…

MISC SETUP…

COMMUNICATIONS SETUP…

---- END ----

Table 4.10 Communications Setup

PROTOCOL = {HTCBUS or MODBUS ASCII

HTCBUS ADDR = {1 to 16777215} (only if PROTOCOL=HTCBUS)

ODBUS ADDR = {1 to 247} (only if PROTOCOLHTCBUS)

ODBUS SUB ADDR = {0 to 31} (only if PROTOCOLHTCBUS)

BAUD RATE = {AUTO or 9600 or 4800

PARITY = {NONE or ODD or EVEN} (only if PROTOCOLHTCBUS)

HARDWARE = {NONE OR MODEM OR

DRIVER = {AUTO or RS-485 or

ROFILE = {AUTO or 3-WIRE RS-232

Tx DELAY = {0.00 to 2.50} S

---- END ----

or MODBUS RTU}

or 2400 or 1200 or
600 or 300}

RS-232 or RS-485}

RS-232 or MODEM}

or RS-485 or 1200 BAUD
MODEM or 300 BAUD
MODEM}

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SECTION 5—CONFIGURATION PARAMETER DETAILS

5.1 INTRODUCTION

The sections that follow explain the various functions of the 910 controller and how they
may be accessed. The first line of each section identifies the function to be described. Each
section goes on to explain the purpose of the function, the range over which it may be set, the
procedure for setting or enabling the feature, and finally any Notes or Cautions that pertain to
the particular function.

Setting and using the alarming functions of the 910 controller is a two step Procedure:

1. The alarm must be enabled or disabled as desired. When using the Operator Console,
access to all alarming functions is available using the ADVANCED CONFIGURE mode
submenus. When using either the Model 780/GCC-9000 Group Communications Controller,
the alarm masks may be found in the HTC SET-UP Section. Please see the appropriate
operating manual for instructions on accessing controller parameters using these devices.

2. The corresponding alarm point value may be modified appropriately for the application.
When using the Operator Console, access to the alarm points is also available using the
ADVANCED CONFIGURE mode sub-menus. Modification of the alarm setpoint values is
found in the HTC SETPOINTS Section of the Model 780/GCC-9000 Group Communications
Controller. Please see the appropriate operating manual for instructions on accessing
controller parameters using these devices.

IMPORTANT: The Operator Console and the Model 780/GCC-9000 will NOT allow modification
of an alarm point value if the alarm has been disabled (DIS) with the exception of the HIGH TS
ALARM temperature settings. These may still be modified if the corresponding HIGH LIMIT
CUTOUT has been enabled (ENA) to incorrect design or factors outside those considered by
the design.

5.2 POINT SETUP PARAMETERS

This section describes the setup parameters that relate to the 910.

5.2.1 CONTROL SETPOINT TEMPERATURE

Purpose: The CONTROL SETPOINT temperature is the value at which the heat trace

controller maintains the circuit temperature through either proportional, proportional ambient
SSR, proportional ambient contactor, or deadband control, depending on the controllers’
configuration. The CONTROL SETPOINT temperature is compared to the temperature
measured by the control temperature sensor (TS). A decision is then made to turn on or turn
off the output to control power to the tracer.

Range: –76°F to 1058°F (–60°C to 570°C)
Procedure: Adjust the CONTROL SETPOINT temperature value to the desired maintain

temperature. The HTC will switch the output ON and OFF in an attempt to maintain this
temperature.

IMPORTANT:

• See Section 7.2 of this manual for an explanation of Proportional, Proportional Ambient
SSR, Proportional Ambient Contactor, and Deadband Control algorithms.

• When using the Operator Console, the CONTROL SETPOINT temperature range may
be limited by the CONSOLE SETPOINT MAXIMUM and MINIMUM values (see Sections

5.2.23 and 5.2.24). This is a safety feature to prevent users in the field from modifying the
CONTROL SETPOINT temperature setting to a dangerous level.

5.2.2 ALPHANUMERIC TAG ASSIGNMENT

Purpose: A 19 character alphanumeric TAG may be assigned to a control point to allow it to be

easily associated with a pipe, vessel, process, circuit, drawing name, or number.

Setting: Any combination of 19 characters from A–Z, 0–9, /, -, ., (, ), or #.
Procedure: Using the Operator Console, enter the desired text.

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5.2.3 SWITCH CONTROL MODE

Purpose: This allows selection of the type of algorithm to be used by the HTC to maintain the

CONTROL SETPOINT temperature. There are four different control algorithms available in the
HTC—proportional, proportional ambient SSR, proportional ambient contactor, and deadband. See
Section 7.2 for a complete explanation of these controlling techniques as implemented in the HTC.

Setting: PROPORTIONAL, PROPORTIONAL AMBIENT SSR, PROPORTIONAL AMBIENT
CONTACTOR, or DEADBAND

Procedure: Select the desired control technique. Note that deadband control and proportional
ambient contactor should be selected when using contactors or when precise control and
advanced current handling functions are not required.

IMPORTANT: If deadband is selected, a DEADBAND setting will be available in the HTC
configuration menu; otherwise, a PROPORTIONAL BAND setting will be available. No
MAXIMUM POWER, SWITCH CURRENT RATING, or CIRCUIT BREAKER CURRENT RATING
settings are available when the controller is set to operate in either contactor mode. If
proportional ambient contactor is selected, the CYCLE TIME setting will also be available.

5.2.4 PROPORTIONAL BAND SETTING

(For use with the three proportional control modes only).
Purpose: When an HTC equipped with SSRs is used to control a heating circuit, proportional or

proportional ambient SSR modes are normally used, allowing for more precise tem- perature
control. When using contactors, the proportional ambient contactor mode should be selected.

This programmable proportional band acts to vary the on to off time of the output based
on the difference between the measured control temperature and the desired CONTROL
SETPOINT temperature.

Range: 2°F to 90°F (1°C to 50°C)
Procedure: Adjust the PROPORTIONAL BAND setting to the desired differential from the

CONTROL SETPOINT temperature.

IMPORTANT:

• See Section 7.2 of this manual for an explanation of how the three proportional modes use

the PROPORTIONAL BAND setting.

• When using Series-type, constant wattage, or self-regulating tracers in an ambient tem-

perature control application, significant energy savings may be realized by setting the
PROPORTIONAL BAND to match the expected range of operating ambient temperatures.
Tracer design is normally done assuming worst-case conditions, where 100% of the design
output power is required to maintain the desired minimum temperature. When the ambient
temperature is above the design minimum, but some heat is still required, adjusting the
PROPORTIONAL BAND width accordingly will allow only the amount of power required by the
application to be consumed, while maintaining the minimum required temperature.

Example: A water line must be protected from freezing when the ambient temperature falls
below 10°C. Either the proportional ambient SSR or proportional ambient contactor mode is
selected as the control method (depending on the type of switch being used). The heater and
insulation combination are chosen to impart enough heat to the line to keep it from freezing at a
worst-case ambient temperature of –40°C. At 10°C, the heater should be completely off, since no
heat is required at this temperature to guarantee that the product will not freeze. It follows that
the amount of heat required by the water line decreases as the ambient temperature increases
from –40°C to 10°C (theoretically, at –15°C the heater output should be approximately 50%).
Setting the CONTROL SETPOINT temperature to 10°C, and the PROPORTIONAL BAND to 50°C,
will force the controller’s output to be 100% on at –40°C, 50% on at –15°C, and off at 10°C.

5.2.5 DEADBAND SETTING

(Deadband control mode only)
Purpose: When an HTC equipped with a contactor is used to control a heating circuit, it is

necessary to use deadband rather than proportional control. This is done to prevent the
contactor from switching on and off rapidly and being worn out prematurely. This deadband
acts as an on/off control where the decision to turn the output off or on is based upon a
window of difference between the measured control temperature and the desired CONTROL
SETPOINT temperature.

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Range: 2°F to 90°F (1°C to 50°C)
Procedure: Adjust the DEADBAND setting to the desired differential from the desired CONTROL

SETPOINT temperature. When the control temperature is above the setpoint + deadband value,
the controller will turn off the output to the tracer. If the control temperature drops down below
the setpoint, the output will be turned back on. Note that the smaller the DEADBAND setting,
the more often the contactor will cycle on and off, decreasing its operational life.

IMPORTANT: See Section 7.2 of this manual for an explanation of Deadband Control. Note
that the MAXIMUM POWER, SWITCH CURRENT RATING, and CIRCUIT BREAKER CURRENT
RATING settings are not available when the HTC is set to Deadband mode (typically when
switching a contactor).

5.2.6 CYCLE TIME SETTING

(For proportional ambient contactor control mode only).
Purpose: This parameter determines the minimum amount of time it will take for a complete

contactor ON-OFF-ON cycle.

Range: 10 to 255 minutes
Procedure: Adjust the CYCLE TIME setting to yield the desired contactor ON+OFF time for

a particular duty cycle. For instance, if the contactor should remain on for five minutes with
a 50% duty cycle, then the CYCLE TIME should be 10 minutes. A new duty cycle (based on
measured control temperature, PROPORTIONAL BAND, and CONTROL SETPOINT) is calculated
every time the contactor is required to change state.

IMPORTANT:

• If the calculated duty cycle is 0% or 100%, then the contactor will not change state and the
duty cycle will not be calculated again for a time period = CYCLE TIME/30.

• The minimum cycle time setting is 10 minutes, and the minimum controller output duty cycle
is 3%. This results in a minimum contactor ON time of 18 seconds.

5.2.7 SWITCH CURRENT RATING SETTING (SSR ONLY)

Purpose: The SWITCH CURRENT RATING setting defines the current rating of the output

switch. It is used by the controller to limit the maximum average current that will be allowed to
flow to the load before it begins to adjust the output duty cycle, limiting the amount of current
to an acceptable level.

Range: 0.3 to 100.0 Amps
Procedure: Adjust the SWITCH CURRENT RATING setting to the match the current rating of the

output device (i.e. 30.0 Amps).

5.2.8 CIRCUIT BREAKER CURRENT RATING SETTING (SSR ONLY)

Purpose: The CIRCUIT BREAKER CURRENT RATING setting helps prevent in-rush induced

nuisance tripping of the circuit breaker immediately upstream of the controller. The HTC
evaluates the square of the current related to time (I

2

t) and adjusts the output duty cycle

accordingly, limiting the amount of current to an acceptable level.

Range: 0.3 to 100.0 Amps
Procedure: Adjust the CIRCUIT BREAKER CURRENT RATING setting to the heating circuit

breaker size (i.e. 30.0 Amps).
IMPORTANT: This feature should NOT be used to reduce the size of a circuit breaker or

increase the maximum heating cable length. It can be quite effective in preventing nuisance
trips due to incorrect design or factors outside those considered by the design.

5.2.9 MAXIMUM POWER SETTING (SSR ONLY)

Purpose: This user selectable level limits the maximum amount of power applied to a heat

trace circuit. This is an average power calculated by the controller using the average current
and applied voltage. The HTC switches the output on and off rapidly to limit the average
current to an appropriate level. The MAXIMUM POWER level may be adjusted to eliminate
stepdown transformers, lower the effective output wattage of a cable, or implement energy
management of the heat trace circuit.

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Range: 3 to 33,000 Watts
Procedure: Adjust the MAXIMUM POWER level to the desired value (watts). Use the TEST

TRACING function to observe the power limiting operation.

IMPORTANT:

• This function may be set within reasonable limits for the particular tracer being powered.
The effective resolution of the setting is limited to 1/30th of the calculated full on power.

• Do not set the MAXIMUM POWER below full output for applications that do not require
power limiting.

5.2.10 TS FAIL MODE

Purpose: This parameter determines whether the HTC turns the output switch ON or OFF if all

selected temperature sensors fail to provide a valid control temperature.

Setting: OFF or ON
Procedure: If the HTC should turn the output switch off when it cannot read a valid control

temperature, then select OFF, otherwise if the output switch should turn on, then select ON.

IMPORTANT: This parameter is part of the TS CONTROL MODE.

5.2.11 TEMPERATURE SENSOR CONTROL MODE

Purpose: The TS CONTROL MODE allows the selection of one of eight possible temperature

control modes for the controller. The different modes allow redundant fail-safe temperature
sensing, averaging, or minimum maintain temperature control.

Setting: Select one of the following eight possible modes:
CONTROL TS AND DESCRIPTION

CONTROL USING TS 1, FAIL OFF/ON
CONTROL USING TS 1, FAIL TO TS 2
CONTROL USING TS 2, FAIL OFF/ON
CONTROL USING TS 2, FAIL TO TS 1
CONTROL ON AVERAGE, FAIL OFF/ON
CONTROL ON AVERAGE, FAIL TO GOOD
CONTROL ON LOWEST, FAIL OFF/ON
CONTROL ON LOWEST, FAIL TO GOOD

Where OFF/ON = Controllers’ output switch turned OFF or ON as determined by the TS FAIL MODE.
Example: With a TS CONTROL MODE of CONTROL ON AVERAGE, FAIL TO GOOD, the controller

will measure both sensors (TS 1 and TS 2), averaging the two temperature values, display the
results, and cycle the heater ON or OFF to maintain the CONTROL SETPOINT temperature. This
is the primary control mode. If either sensor should fail, the controller will transfer control to
the remaining “good” sensor and generate the appropriate TS 1 or TS 2

FAILURE ALARM (assuming that the alarm is enabled). The temperature will now be
maintained based on this measured value. If the remaining “good” sensor fails, the controller
will turn the heater OFF or ON as determined by the TS FAIL MODE setting. The appropriate TS

1 or TS 2 FAILURE ALARM will be also be generated.

Procedure: Select the control mode that best suits the application.
IMPORTANT: Ensure that TS FAILURE ALARMS are enabled. See Sections 5.4.1, 5.4.4, and

5.4.10 for a complete explanation of RTD failure detection in the HTC.

5.2.12 TS 1 TYPE

Purpose: This parameter specifies the type of RTD that is connected to the HTC’s TS 1 input.
Setting: 3 wire 100 Ω Platinum or 2 (or 3) wire 100 Ω Nickel Iron (NI-FE).
Procedure: Select the type of RTD that is connected to the TS 1 input.
IMPORTANT: If a 2 wire 100 Ω Nickel Iron (NI-FE) RTD is selected then the TS 1 LEAD

RESISTANCE must be entered manually (see Section 5.2.13).

5.2.13 TS 1 LEAD RESISTANCE

(For NI-FE RTDs only.)

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Purpose: This parameter specifies the lead resistance of a 2 wire Nickel Iron RTD connected to
the HTC’s TS 1 input.

Range: 0 to 20.00 Ω
Procedure: Measure the resistance of one of the Nickel Iron RTD leads (from the RTD to the

HTC’s TS 1 input) and use this value as the TS 1 LEAD RESISTANCE.

5.2.14 TS 1 HIGH LIMIT CUTOUT

Purpose: When enabled, the TS 1 high limit cutout feature will override the CONTROL

SETPOINT temperature and force the controller output off if the TS 1 reading exceeds the
HIGH TS 1 ALARM temperature setting. This is a non-latching condition, so once the TS 1
reading drops below the HIGH TS 1 ALARM temperature setting, the controller will resume
normal operation.

Setting: ENABLE or DISABLE
Procedure: Enable or disable the cutout feature as desired.
IMPORTANT:

• The TS 1 HIGH LIMIT CUTOUT feature overrides an autocycle test. A pending autocycle
will be initiated immediately after the TS 1 temperature drops below the HIGH TS 1 ALARM
temperature setting.

• If a TS 1 failure occurs and the TS 1 HIGH LIMIT CUTOUT feature is enabled, the switch output

will latch off regardless of the TS CONTROL MODE setting or the TS FAIL MODE setting.

• If the TS 1 HIGH LIMIT CUTOUT feature is enabled, then the HIGH TS 1 ALARM temperature

setting can be set, regardless of whether the HIGH TS 1 ALARM is enabled.

5.2.15 TS 2 TYPE

Purpose: This parameter specifies the type of RTD that is connected to the HTC’s TS 2 input.
Setting: 3 wire 100 Ω Platinum or 2 (or 3) wire 100 Ω Nickel Iron (NI-FE).
Procedure: Select the type of RTD that is connected to the TS 2 input.
IMPORTANT: If a 2 wire 100 Ω Nickel Iron (NI-FE) RTD is selected then the TS 2 LEAD

RESISTANCE must be entered (see Section 5.2.16).

5.2.16 TS 2 LEAD RESISTANCE

(For NI-FE RTDs only.)
Purpose: This parameter specifies the lead resistance of a 2 wire Nickel Iron RTD connected to

the HTC’s TS 2 input.

Range: 0 to 20.00 Ω
Procedure: Measure the resistance of one of the Nickel Iron RTD leads (from the RTD to the

HTC’s TS 2 input) and use this value as the TS 2 LEAD RESISTANCE.

5.2.17 TS 2 HIGH LIMIT CUTOUT

Purpose: When enabled, the TS 2 high limit cutout feature will override the CONTROL

SETPOINT temperature and force the controller output off if the TS 2 reading exceeds the
HIGH TS 2 ALARM temperature setting. This is a non-latching condition, so once the TS 2
reading drops below the HIGH TS 2 ALARM temperature setting, the controller will resume
normal operation.

Setting: ENABLE or DISABLE
Procedure: Enable or disable the cutout feature as desired.
IMPORTANT:

• The TS 2 HIGH LIMIT CUTOUT feature overrides an autocycle test. A pending autocycle
will be initiated immediately after the TS 2 temperature drops below the HIGH TS 2 ALARM
temperature setting.

• If a TS 2 failure occurs and the TS 2 HIGH LIMIT CUTOUT feature is enabled, the switch output

will latch off regardless of the TS CONTROL MODE setting or the TS FAIL MODE setting.

• If the TS 2 HIGH LIMIT CUTOUT feature is enabled, then the HIGH TS 2 ALARM temperature

setting can be set, regardless of whether the HIGH TS 2 ALARM is enabled.

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5.2.18 AUTOCYCLE ENABLING

Purpose: The autocycle function momentarily (approximately 10 seconds) applies power to

the heating circuit at the selected interval. It is used to test the integrity of the heating circuit.
Alarms present at the time of autocycle then become latched and remain active after

the completion of the autocycle function. Autocycling effectively eliminates the need for
preventive maintenance by automatically verifying the heating circuit integrity.

Setting: ENABLE or DISABLE
Procedure: Enable or disable the autocycling feature as desired. If the feature is disabled,

you will not be prompted to enter the AUTOCYCLE INTERVAL or AUTOCYCLE UNITS.

IMPORTANT:

• Autocycling should always be enabled for normal operation. Disabling this feature should
only be required where the HTC system is monitoring a circuit exercised by some other
device or means. Although this function defeats temperature control and forces output on,
the controller will continue to adjust the output for protection purposes or power limiting
(SSR option only).

• Autocycling is inhibited if the controller is in the load shedding mode. See Section 7.3.

• If autocycling is enabled, the HTC will always autocycle for 10 seconds when power is
initially applied.

• If autocycling is enabled, and TS FAIL MODE = OFF and all the control temperature sensors
have failed, the HTC will still perform an autocycle.

• If an alarm condition with an alarm filter time greater than 0 appears during the autocycling,
then the autocycle will be extended (past the 10 seconds) until the alarm filter time has
expired.

5.2.19 AUTOCYCLE TIME INTERVAL

Purpose: AUTOCYCLE INTERVAL is the number of hours/minutes between successive heating

circuit integrity tests depending on the AUTOCYCLE UNITS specified.

Range: 1 to 240
Procedure: Set the AUTOCYCLE INTERVAL to the desired time period.
IMPORTANT:

• When using proportional ambient contactor mode, the CYCLE TIME setting should be less
than the AUTOCYCLE INTERVAL; otherwise, autocycling could affect the duty-cycle.

• If an AC ALARM becomes active during an autocycle, but the AUTOCYCLE INTERVAL expires
prior to the corresponding ALARM FILTER time, then autocycling will continue until the
ALARM FILTER time has elapsed.

• For the earliest possible alarming of heating circuit problems, the AUTOCYCLE INTERVAL

should be set to a small value.

5.2.20 AUTOCYCLE TIME UNITS

Purpose: The autocycle time units parameter allows selection of minutes or hours for the

AUTOCYCLE INTERVAL setting.

Setting: HOURS or MINUTES
Procedure: Set the AUTOCYCLE UNITS to the desired time units.

5.2.21 OVERRIDE SOURCE

Purpose: An override signal can be sent to the HTC from one of two sources. This override

signal can be used to override the controller’s temperature control and force the output switch
off or on. This is especially useful when the user wishes to turn a controller or a group of
controllers off over the summer months, during maintenance, or when a line is flowing and
does not require heating.

Setting: REMOTE or EXT. INPUT
Procedure: If the override signal will be generated remotely and received by the HTC via the

optional communications interface, select REMOTE as the OVERRIDE SOURCE. If the
override signal will be received by the HTC via the external input, select EXTERNAL INPUT as
the OVERRIDE SOURCE.

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IMPORTANT:

• If the EXTERNAL INPUT is not configured as either INHIBIT or FORCE ON then OVERRIDE
SOURCE will always automatically be set to REMOTE. See Section 5-3-3 for further details.

• If the autocycle feature is enabled, it will continue to function even when an INHIBIT override
signal is being received as long as load shedding is not active.

• Fail safe mode is inactive if an INHIBIT override signal is being received.

• Load shedding and fail safe modes are inactive if a FORCE ON override signal is being received.

• Only the LOW TS ALARMS for temperature sensors used by the TS CONTROL MODE are
inactive if an INHIBIT override signal is being received.

5.2.22 LOAD SHEDDING ENABLING

Purpose: The load shedding function allows the controller output to be forced OFF by way of a

remote contact input on the 780 Group Communications Controller or using the communications
port and an upstream device. It may be used to turn OFF the output of one or more controllers
in order to reduce energy consumption to avoid peak demand surcharges, remove power from
unused circuits, or remove power from circuits which may be subjected to steam cleaning.

Setting: ENABLE or DISABLE
Procedure: Enable or disable the load shedding control mode as desired.
IMPORTANT: To completely configure the HTC for load shedding operation, the following

additional parameters must be set up using the Model 780/GCC-9000:
Fail Safe Mode
Load Shedding GCC Contact Association
These additional parameters may only be accessed using the Group Communications
Controller. See the appropriate Section of the GCC manual for further details.

IMPORTANT:

• Fail safe mode is not supported when using proportional ambient SSR or proportional
ambient contactor modes.

• For fail safe mode to function, at least one LOW TS ALARM of the controlling temperature
sensor(s) must be enabled and the corresponding LOW TS ALARM temperature setting must
be less than the CONTROL SETPOINT temperature.

5.2.23 CONSOLE SETPOINT MAXIMUM

Purpose: When using the Operator Console the maximum setting of the CONTROL SETPOINT

temperature may be limited to the CONSOLE SETPOINT MAXIMUM value. This is a safety
feature to prevent users in the field from modifying the CONTROL SETPOINT temperature
setting to a dangerous level.

Range: –76°F to 1058°F (–60°C to 570°C)
Procedure: Adjust the CONSOLE SETPOINT MAXIMUM temperature value to limit the maximum

allowable CONTROL SETPOINT TEMPERATURE that may be set using the Operator Console.
The CONSOLE SETPOINT MAXIMUM may only be set using a communicating device such as
the Model 780/GCC-9000. See the 780/GCC-9000 user manual for the proper procedure.

IMPORTANT: The CONSOLE SETPOINT MAXIMUM is not displayed on the Operator Console.

5.2.24 CONSOLE SETPOINT MINIMUM

Purpose: When using the Operator Console the minimum setting of the CONTROL SETPOINT

temperature may be limited to the CONSOLE SETPOINT MINIMUM value. This is a safety
feature to prevent users in the field from modifying the CONTROL SETPOINT temperature
setting to a dangerous level.

Range: –76°F to 1058°F (–60°C to 570°C)
Procedure: Adjust the CONSOLE SETPOINT MINIMUM temperature value to limit the minimum

allowable CONTROL SETPOINT TEMPERATURE that may be set using the Operator Console.
The CONSOLE SETPOINT MINIMUM may only be set using a communicating device such as
the Model 780/GCC-9000. See the 780/GCC-9000 manual for the proper procedure.

IMPORTANT: The CONSOLE SETPOINT MINIMUM is not displayed on the Operator Console.

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5.3 MISCELLANEOUS SETUP PARAMETERS

The following section describes miscellaneous the setup parameters.

5.3.1 TEMPERATURE DISPLAY UNITS

Purpose: This allows selection of the type of temperature units to display on the Operator

Console. All temperature related values will be displayed in the selected units.
IMPORTANT: This setting will not affect the temperature units displayed at a 780/GCC-9000

Group Communications Controller. The GCC may be set independently.

Setting: DEGREES F or DEGREES C
Procedure: Adjust the setting to the desired temperature units (°F or °C).
IMPORTANT: To minimize possible confusion, it is recommended that the temperature units

be set the same on the HTC and any other communicating devices.

5.3.2 VERSION OF FIRMWARE AND HARDWARE

Purpose: The first three digits indicate the revision level of the firmware programmed into the

controller. As new features are added to the HTC, the firmware revision level is incremented to
allow the user to determine which features are available for the particular unit being used.

5.3.3 EXTERNAL INPUT PORT

Purpose: This input port may be used as an OVERRIDE SOURCE to sense a remote dry contact

closure. This will override the controller’s temperature control and force its output switch off or on.

Setting: NOT USED, INHIBIT, or FORCE ON
Procedure: If the EXTERNAL INPUT is not being used, select NOT USED. If a remote dry

contact closure should force the output switch off then select INHIBIT. If a remote dry contact
closure should force the output switch on, then select FORCE ON.

If the EXTERNAL INPUT is set to INHIBIT or FORCE ON, then OVERRIDE SOURCE must be set to
EXT. INPUT.

IMPORTANT:

• When used with the INHIBIT/FORCE ON feature, a contact closure sensed by the EXTERNAL
INPUT will initiate the INHIBIT/FORCE ON mode. An open input will cause the controller to
revert to normal temperature control operation.

One possible use of the INHIBIT feature is to use an external device (such as a flow meter)

to provide a contact closure if there is flow in a line. As long as the line has adequate flow,
the heating will be off (INHIBITed from operating). See Appendix C for typical connection
diagrams when using this input.

• EXTERNAL INPUT must be set to INHIBIT or FORCE ON before OVERRIDE SOURCE can be
set to EXT. INPUT. Setting EXTERNAL INPUT to NOT USED or TEMPBUS™ will automatically
set OVERRIDE SOURCE to REMOTE.

5.3.4 FLASH ALARM OUTPUT SETTING

Purpose: Programs both the alarm output relays (dry contact and AC alarm) for flashing or

steady output in case of an alarm condition.

Setting: YES (Flash) or NO (Steady)
Procedure: Set the alarm output relays to flash or not to flash on an alarm condition, whichever

suits the application.

IMPORTANT:

• If the alarm output is used to drive a pilot light, it is recommended that YES be selected

to enable flashing operation. When the output is also configured for normally closed
operation, the pilot light will be on steady for normal operation, flash in case of alarm, and be
extinguished due to a bulb failure or loss of power.

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• If multiple alarm outputs from different controllers are wired in series (i.e.: multi-point
panels), set this parameter to NO (steady).

5.3.5 ALARM OUTPUT NORMAL STATE

Purpose: Configures both the alarm output relays (dry contact and AC alarm) for normally

open or normally closed operation. The normal condition is assumed to be when the HTC is
powered and no alarms exist.

Setting: N.O. (Normally Open) or N.C. (Normally Closed)
Procedure: Set the alarm output relays to normally open or normally closed to suit the

application.
IMPORTANT: If a pilot light is used for indication of alarms, normally closed operation

provides a steady illumination of the lamp when the circuit is operating correctly. A light that is
flashing or out indicates a fault condition. A burned out lamp is readily identified if the HTC is
set to flash the dry contact alarm output relay and the AC Alarm Relay output in case of alarm.

See the Section 5.3.4.

5.3.6 LANGUAGE

Purpose: Defines which language the Operator Console is to use when prompting the user for

input and/or displaying messages and status.

Setting: ENGLISH or FRANCAIS
Procedure: Select the language of choice: ENGLISH for English prompts and messages, or

FRANCAIS for French prompts and messages.

5.3.7 PASSCODE

See Section 5.7.1.

5.3.8 SCROLL DELAY SETTING

Purpose: Allows the user to modify the speed at which information is scrolled on the Operator

Console for ease of viewing.

Range: 0.07 to 0.25 seconds
Procedure: Decreasing the scroll delay value will cause the information on the display to scroll

by faster. Increasing the scroll delay value will cause the information on the display to scroll by
slower.

5.4 TEMPERATURE SENSOR ALARMS CONFIGURATION

This section defines the temperature related alarming functions of the 910 controller.

5.4.1 TEMPERATURE SENSOR 1 FAILURE ALARM

Purpose: Enabling TS 1 FAILURE will provide indication of an open or shorted failure of TS 1.
Alarm Mask: ENABLE or DISABLE
Procedure: Enable or disable alarming of a failed temperature sensor connected to the TS 1

input as required.

IMPORTANT:

• This failure alarm should be enabled if a temperature sensor is connected to the TS 1 input.

• This alarm is always latched and must be reset by the user.

5.4.2 LOW TEMPERATURE SENSOR 1 ALARM

Purpose: If enabled, the LOW TS 1 ALARM allows for alarming of low temperature conditions

as sensed by the first temperature sensor (TS 1).

Alarm Mask: ENABLE or DISABLE
Range: –76°F to 1058°F (–60°C to 570°C)
Procedure: Adjust the LOW TS 1 ALARM temperature setpoint to the desired value. Note that

the LOW TS 1 ALARM must be enabled in order to adjust the LOW TS 1 ALARM
temperature setpoint.

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IMPORTANT:

• This alarm should normally be enabled and the setpoint should be appropriate for the
heating application. Maintaining a minimum 5°C differential between low temperature
alarming and the CONTROL SETPOINT temperature will minimize nuisance alarming due to
momentary dips in temperature. Another alternative to this is to configure the controller for
non-latching temperature alarms.

• This alarm must be enabled and its setpoint must be below the CONTROL SETPOINT
temperature if fail safe mode uses the temperature reading from TS 1.

5.4.3 HIGH TEMPERATURE SENSOR 1 ALARM

Purpose: If enabled, the HIGH TS 1 ALARM allows for alarming of high temperature conditions

as sensed by the first temperature sensor (TS 1).

Alarm Mask: ENABLE or DISABLE
Range: –76°F to 1058°F (–60°C to 570°C)
Procedure: Adjust the HIGH TS 1 ALARM temperature setpoint to the desired value. Note that

the HIGH TS 1 ALARM must be enabled in order to adjust the HIGH TS 1 ALARM temperature
setpoint unless the TS 1 high limit cutout feature is enabled.

IMPORTANT: This alarm should only be used for applications where a product that is sensitive
to over temperature is involved. General usage may result in nuisance alarms due to the flow
of hot product or steam out. This may be a case where the alarm should be enabled and non­latching temperature alarming should be used. A high temperature condition resulting from a
forced on failure of the heating circuit should first be alarmed by the SWITCH FAILURE ALARM.
See Section 5.5.18 for more information.

5.4.4 TEMPERATURE SENSOR 2 FAILURE ALARM

Purpose: Enabling TS 2 FAILURE will provide indication of an open or shorted failure of TS 2.
Alarm Mask: ENABLE or DISABLE
Procedure: Enable or disable alarming of a failed temperature sensor connected to the TS 2

input as required.

IMPORTANT:

• If no second sensor is installed, this alarm should be disabled. This failure alarm should be
enabled if a second temperature sensor is connected to the TS 2 input.

• This alarm is always latched and must be reset by the user.

5.4.5 LOW TEMPERATURE SENSOR 2 ALARM

Purpose: If enabled, the LOW TS 2 ALARM allows for alarming of low temperature conditions

as sensed by the second temperature sensor (TS 2).

Alarm Mask: ENABLE or DISABLE
Range: –76°F to 1058°F (–60°C to 570°C)
Procedure: Adjust LOW TS 2 ALARM temperature setpoint to the desired value. Note that the

LOW TS 2 ALARM must be enabled in order to adjust the LOW TS 2 ALARM
temperature setpoint.

IMPORTANT:

• If no second sensor is installed this alarm should be disabled. This alarm should be
enabled and the setpoint should be appropriate for the heating application. Maintaining a
minimum 5°C differential between low temperature alarming and the CONTROL SETPOINT
temperature will minimize nuisance alarming due to momentary dips in temperature.
Another alternative to this is to configure the controller for non-latching temperature alarms.

• This alarm must be enabled and its setpoint must be below the CONTROL SETPOINT
temperature if fail safe mode uses the temperature from TS 2.

5.4.6 HIGH TEMPERATURE SENSOR 2 ALARM

Purpose: If enabled, the HIGH TS 2 ALARM allows for alarming of high temperature conditions

as sensed by the second temperature sensor (TS 2).
Alarm Mask: ENABLE or DISABLE

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Range: –76°F to 1058°F (–60°C to 570°C)
Procedure: Adjust the HIGH TS 2 ALARM temperature setpoint to the desired value. Note that

the HIGH TS 2 ALARM must be enabled in order to adjust the HIGH TS 2 ALARM temperature
setpoint unless the TS 2 high limit cutout feature is enabled.

IMPORTANT: If no second sensor is installed this alarm should be disabled. This alarm may be
used for applications where a product that is sensitive to over temperature is involved. General
usage could result in nuisance alarms due to the flow of hot product or steam out. This may be
a case where the alarm could be enabled and non-latching temperature alarming used. A high
temperature condition resulting from a forced on failure of the heating circuit should first be
alarmed by the SWITCH FAILURE ALARM. See Section 5.5.18 for more information.

5.4.7 LOW TEMPERATURE SENSOR ALARM FILTER TIME SETTING

Purpose: The LOW TS ALARM FILTER will prevent LOW TS 1 and/or LOW TS 2 ALARMS from

being indicated until their corresponding alarm condition has existed for the duration of the
LOW TS ALARM FILTER time.

Range: 0 to 999 minutes
Procedure: Adjust the LOW TS ALARM FILTER time to the desired value. Note that either the

LOW TS 1 ALARM and/or the LOW TS 2 ALARM must be enabled in order to adjust the LOW TS
ALARM FILTER time.

IMPORTANT:

• If an alarm condition appears and then disappears before the alarm filter time has expired,
the filter timer is reset and the alarm condition must exist again for the entire alarm filter
time before the corresponding alarm will be indicated.

• If the user resets an alarm while the alarm condition is still exists, then the alarm will not be
indicated again until the entire alarm filter time has expired.

5.4.8 HIGH TEMPERATURE SENSOR ALARM FILTER TIME SETTING

Purpose: The HIGH TS ALARM FILTER will prevent HIGH TS 1 and/or HIGH TS 2 ALARMS from

being indicated until their corresponding alarm condition has existed for the duration of the
HIGH TS ALARM FILTER time.

Range: 0 to 999 minutes
Procedure: Adjust the HIGH TS ALARM FILTER time to the desired value. Note that either the

HIGH TS 1 ALARM and/or the HIGH TS 2 ALARM must be enabled in order to adjust the HIGH
TS ALARM FILTER time.

IMPORTANT:

• If an alarm condition appears and then disappears before the alarm filter time has expired,
the filter timer is reset and the alarm condition must exist again for the entire alarm filter
time before the corresponding alarm will be indicated.

• If the user resets an alarm while the alarm condition is still exists, then the alarm will not be
indicated again until the entire alarm filter time has expired.

• The HIGH TS ALARM FILTER time setting will not affect the cutout time when the HIGH LIMIT
CUTOUT feature is enabled.

5.4.9 LATCH TEMPERATURE SENSOR ALARMS SETTING

Purpose: This allows for the selection of automatic clearing of all HIGH and LOW TS ALARMS

(non-latching) when a temperature alarm condition no longer exists or permanent alarming of
such a condition (latching) until the alarm is manually reset.

Setting: YES (LATCHING) or NO (NON-LATCHING)
Procedure: Adjust the LATCH TS ALARMS setting to the desired mode (latching or nonlatching).

IMPORTANT:

• If your application is subject to periodic situations where cold or hot product is part of the
process, it may be appropriate to configure the HTC for non-latching temperature alarms to avoid
nuisance alarms. If it is important to be aware of any temperature alarm conditions that may
have existed in a pipe, then the HTC should be configured for latching temperature alarms.

• This setting does not affect the TS FAILURE ALARMS—these are always latching.

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5.4.10 CONTROL TEMPERATURE SENSOR FAILURE ALARM

Purpose: Control TS FAILURE ALARM indicates a failure of the temperature sensor designated

as the control sensor.
One of eight TS CONTROL MODES may be selected. These modes determine which TS input(s)

is(are) designated to provide the control temperature. See Section 5-2-11 for a full description
of the temperature sensor control designations.

Alarm Mask: ENABLE or DISABLE
Procedure: Enable or disable the alarming of a failure of the designated control temperature

sensor as required.
IMPORTANT: This alarm should always be enabled. If the controller experiences a Control

TS Failure it will turn the output off or on (as specified by TS FAIL MODE) until this alarm is
cleared.

5.5 OTHER ALARMS CONFIGURATION

This section defines the non-temperature-related alarming functions of the 910 controller
(current, ground fault, voltage and resistance).

5.5.1 LOW LOAD CURRENT ALARM

Purpose: Alarms current levels which are lower than a preset limit for the application.

Monitoring for lower than expected current levels may be an effective means of continuity
monitoring. See also HIGH RESISTANCE ALARM in Section 5.5.14.

Alarm Mask: ENABLE or DISABLE
Range: 0.3 to 100.0 Amps
Procedure: Adjust the LOW CURRENT ALARM level to the desired value. Note that the LOW

CURRENT ALARM must be enabled in order to adjust the LOW CURRENT ALARM level.

IMPORTANT:

• For series type heating cables, adjusting the LOW CURRENT ALARM to 50% of full load

current will properly alarm a problem and reduce nuisance alarms due to voltage dips.
Parallel heaters should be adjusted to a level as close as possible to full load current but
lower than the current at worst case voltage. The low current setting as a percentage of full
load current will vary depending on the facility and its power system.

• A LOW CURRENT ALARM may also result from a switch failed open. The controller cannot

detect a switch failure due to no current. A no current condition would be identified by a LOW
CURRENT ALARM (if enabled) and the analog value reported with the alarm will be 0.0 A.

• It may be advantageous to consider using the HIGH RESISTANCE ALARM to indicate a cable

fault when using certain types of heaters. See Sections 5.5.12 and 5.5.14 for an explanation
of the resistance alarming feature.

5.5.2 LOW LOAD CURRENT ALARM FILTER TIME SETTING

Purpose: The LOW CURRENT ALARM FILTER will prevent LOW LOAD CURRENT ALARMS from

being indicated until a low current condition has existed for the duration of the LOW CURRENT
ALARM FILTER time.

Range: 0 to 12 seconds
Procedure: Adjust the LOW CURRENT ALARM FILTER time to the desired value. Note that the

LOW CURRENT ALARM must be enabled in order to adjust the LOW CURRENT ALARM FILTER

time.

IMPORTANT:

• If an alarm condition appears and then disappears before the alarm filter time has expired,

• If the user resets an alarm while the alarm condition is still exists, then the alarm will not be

5.5.3 HIGH LOAD CURRENT ALARM

Purpose: Alarms current levels which are higher than a preset limit for the application.

the filter timer is reset and the alarm condition must exist again for the entire alarm filter
time before the corresponding alarm will be indicated.

indicated again until the entire alarm filter time has expired.

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Alarm Mask: ENABLE or DISABLE
Range: 0.3 to 100.0 Amps
Procedure: Adjust the HIGH CURRENT ALARM level to the desired value. Note that the HIGH

CURRENT ALARM must be enabled in order to adjust the HIGH CURRENT ALARM level.
IMPORTANT: As the HTC automatically protects itself from overload, it would not normally

be necessary to enable this alarm. This automatic protection can be used effectively to
guard against accidental paralleling of heating circuits. In-rush, or cold start currents typically
associated with self-regulating cables, may cause nuisance HIGH CURRENT ALARMS. If this is
undesirable this alarm should be disabled.

5.5.4 HIGH LOAD CURRENT ALARM FILTER TIME SETTING

Purpose: The HIGH CURRENT ALARM FILTER will prevent HIGH LOAD CURRENT ALARMS

from being indicated until a high current condition has existed for the duration of the HIGH
CURRENT ALARM FILTER time.

Range: 0 to 12 seconds
Procedure: Adjust the HIGH CURRENT ALARM FILTER time to the desired value. Note that the HIGH

CURRENT ALARM must be enabled in order to adjust the HIGH CURRENT ALARM FILTER time.

IMPORTANT:

• If an alarm condition appears and then disappears before the alarm filter time has expired,
the filter timer is reset and the alarm condition must exist again for the entire alarm filter
time before the corresponding alarm will be indicated.

• If the user resets an alarm while the alarm condition is still exists, then the alarm will not be
indicated again until the entire alarm filter time has expired.

5.5.5 HIGH GROUND FAULT CURRENT ALARM

Purpose: Alarms ground fault current levels which are higher than a preset limit for the

application.

Alarm Mask: ENABLE or DISABLE
Range: 20 to 250 mAmps
Procedure: Adjust the HIGH GFI ALARM level to the desired value. Note that the HIGH GFI

ALARM must be enabled in order to adjust the HIGH GFI level.

5.5.6 HIGH GROUND FAULT CURRENT ALARM FILTER TIME SETTING

Purpose: The HIGH GFI ALARM FILTER will prevent HIGH GFI ALARMS from being indicated

until a high GFI condition has existed for the duration of the HIGH GFI ALARM FILTER time.

Range: 0 to 12 seconds
Procedure: Adjust the HIGH GFI ALARM FILTER time to the desired value. Note that the

HIGH GFI ALARM must be enabled in order to adjust the HIGH GFI ALARM FILTER time.

IMPORTANT:

• If an alarm condition appears and then disappears before the alarm filter time has expired,
the filter timer is reset and the alarm condition must exist again for the entire alarm filter
time before the corresponding alarm will be indicated.

• If the user resets an alarm while the alarm condition is still exists, then the alarm will not be
indicated again until the entire alarm filter time has expired.

5.5.7 GROUND FAULT TRIP ALARM

Purpose: This value sets the upper limit of allowable ground fault leakage current. Exceeding

this limit will result in the output switch being latched off and the GFI TRIP ALARM activated to
indicate a ground fault condition.

Alarm Mask: ENABLE or DISABLE
Range: 20 to 250 mAmps
Procedure: If ground fault tripping is desired, enable the GFI TRIP ALARM and adjust the G.F.

TRIP CURRENT to the desired value. To disable ground fault tripping, disable the alarm.
Note that the

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GFI TRIP ALARM must be enabled in order to adjust the G.F. TRIP CURRENT level.

CAUTION:

In order to implement a ground fault trip function, ALL NON-GROUNDED power conductors
must be opened upon detection of a ground fault condition.

IMPORTANT: National Electrical Codes may require that all legs of non-neutral based power
sources be opened upon detection of a Ground Fault. Multi-pole switch configurations
should be used on non-neutral based power systems. Check the requirements with your local
Electrical Authority.

5.5.8 LOW VOLTAGE ALARM

Purpose: Alarms voltage levels that are lower than a preset limit for the application.
Alarm Mask: ENABLE or DISABLE
Range: 10 to 330 Volts
Procedure: Adjust the LOW VOLTAGE ALARM level to the desired value. Note that the LOW

VOLTAGE ALARM must be enabled in order to adjust the LOW VOLTAGE ALARM level.

IMPORTANT: It is recommended that the LOW VOLTAGE ALARM always be enabled.

5.5.9 LOW VOLTAGE ALARM FILTER TIME SETTING

Purpose: The LOW VOLTAGE ALARM FILTER will prevent LOW VOLTAGE ALARMS from being

indicated until a low voltage condition has existed for the duration of the LOW VOLTAGE
ALARM FILTER time.

Range: 0 to 12 seconds
Procedure: Adjust the LOW VOLTAGE ALARM FILTER time to the desired value. Note that the

LOW VOLTAGE ALARM must be enabled in order to adjust the LOW VOLTAGE ALARM FILTER

time.

IMPORTANT:

• If an alarm condition appears and then disappears before the alarm filter time has expired,

the filter timer is reset and the alarm condition must exist again for the entire alarm filter
time before the corresponding alarm will be indicated.

• If the user resets an alarm while the alarm condition is still exists, then the alarm will not be

indicated again until the entire alarm filter time has expired.

5.5.10 HIGH VOLTAGE ALARM

Purpose: Alarms voltage levels that are higher than a preset limit for the application. Serves as

a monitor of the voltage used to power the tracing circuit.

Alarm Mask: ENABLE or DISABLE
Range: 10 to 330 Volts
Procedure: Adjust the HIGH VOLTAGE ALARM level to the desired value. Note that the HIGH

VOLTAGE ALARM must be enabled in order to adjust the HIGH VOLTAGE ALARM level.

5.5.11 HIGH VOLTAGE ALARM FILTER TIME SETTING

Purpose: The HIGH VOLTAGE ALARM FILTER will prevent HIGH VOLTAGE ALARMS from being

indicated until a high voltage condition has existed for the duration of the HIGH VOLTAGE
ALARM FILTER time.

Range: 0 to 12 seconds
Procedure: Adjust the HIGH VOLTAGE ALARM FILTER time to the desired value. Note that the HIGH

VOLTAGE ALARM must be enabled in order to adjust the HIGH VOLTAGE ALARM FILTER time.

IMPORTANT:

• If an alarm condition appears and then disappears before the alarm filter time has expired,

the filter timer is reset and the alarm condition must exist again for the entire alarm filter
time before the corresponding alarm will be indicated.

• If the user resets an alarm while the alarm condition is still exists, then the alarm will not be

indicated again until the entire alarm filter time has expired.

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5.5.12 LOW RESISTANCE ALARM

Purpose: Alarms heater resistance levels that have decreased from the NOMINAL

RESISTANCE setting by more than the selected amount.

Alarm Mask: ENABLE or DISABLE
Range: 1% to 100% (deviation from NOMINAL RESISTANCE)
Procedure: Adjust the LOW RESISTANCE ALARM deviation to the desired value. Note that the

LOW RESISTANCE ALARM must be enabled in order to adjust the LOW RESISTANCE deviation.

IMPORTANT:

• This feature would not normally be enabled. It can be used effectively to guard against
accidental paralleling of heating circuits. Care must be taken when using this alarm feature
with heating cables that exhibit a variable resistance with temperature. Low resistance
alarming may not be practical when the load has an increasing resistance with temperature
(such as self-regulating cables).

• Use of the LOW RESISTANCE ALARM assumes that the controller power is derived from
the same circuit as the tracing power (either by direct connection or through a step-down
transformer).

• No LOW RESISTANCE ALARMS will be generated if the measured voltage is below the LOW
VOLTAGE ALARM setpoint, regardless if the LOW VOLTAGE ALARM is enabled. This stops
an alarm from being generated when the circuit power is turned off. If the LOW VOLTAGE
ALARM is disabled, ensure that the LOW VOLTAGE setpoint is set to a relevant level
otherwise no LOW RESISTANCE ALARMS will occur.

• LOW RESISTANCE ALARMS will only be generated if the output switch is on.

5.5.13 LOW RESISTANCE ALARM FILTER TIME SETTING

Purpose: The LOW RESISTANCE ALARM FILTER will prevent LOW RESISTANCE ALARMS

from being indicated until a low resistance condition has existed for the duration of the LOW
RESISTANCE ALARM FILTER time.

Range: 0 to 12 seconds
Procedure: Adjust the LOW RESISTANCE ALARM FILTER time to the desired value. Note that

the LOW RESISTANCE ALARM must be enabled in order to adjust the LOW RESISTANCE
ALARM FILTER time.

IMPORTANT:

• If an alarm condition appears and then disappears before the alarm filter time has expired,
the filter timer is reset and the alarm condition must exist again for the entire alarm filter
time before the corresponding alarm will be indicated.

• If the user resets an alarm while the alarm condition is still exists, then the alarm will not be
indicated again until the entire alarm filter time has expired.

5.5.14 HIGH RESISTANCE ALARM

Purpose: Alarms heater resistance levels that have increased from the NOMINAL RESISTANCE

setting by more than the selected amount. The HIGH RESISTANCE ALARM may be used to
indicate an open or a high resistance connection or, when using constant wattage parallel
cables, may indicate the failure of one or more heating zones. It may also be used to monitor
a failed series-type cable or connection in three-phase applications while minimizing nuisance
alarms created by voltage fluctuations.

Alarm Mask: ENABLE or DISABLE
Range: 1% to 250% (deviation from NOMINAL RESISTANCE)
Procedure: Adjust the HIGH RESISTANCE ALARM level to the desired value. Note that the

HIGH RESISTANCE ALARM must be enabled in order to adjust the HIGH RESISTANCE deviation.

IMPORTANT:

• Using the LOW CURRENT ALARM feature to ensure that unexpected decreases in current

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consumption by the heating cable are alarmed is a reliable method of monitoring the integrity
of series-type heating cables. When using parallel-type heaters (zoned constant wattage or
self-regulating) or in three-phase installations, the LOW CURRENT ALARM setting must be
chosen as close to the lowest expected current as possible to detect failed zones, or cable
degradation,

or a lost phase. The problem with such a close setting is that it inevitably leads
to nuisance alarms, particularly when voltage fluctuations are present. By using the HIGH

RESISTANCE ALARM, nuisance alarms due to voltage dips may be minimized.

• Use of the HIGH RESISTANCE ALARM assumes that the controller power is derived from the
same circuit as the tracing power.

• No HIGH RESISTANCE ALARMS will be generated if the measured voltage is below the LOW
VOLTAGE ALARM setpoint, regardless of whether the LOW VOLTAGE ALARM is enabled. This
stops an alarm from being generated when the circuit power is turned off.

If the LOW VOLTAGE ALARM is disabled ensure that the LOW VOLTAGE setpoint is set to a

relevant level otherwise no HIGH RESISTANCE ALARMS will occur.

• HIGH RESISTANCE ALARMS will only be generated if the output switch is on.

5.5.15 HIGH RESISTANCE ALARM FILTER TIME SETTING

Purpose: The HIGH RESISTANCE ALARM FILTER will prevent HIGH RESISTANCE ALARMS

from being indicated until a high resistance condition has existed for the duration of the HIGH
RESISTANCE ALARM FILTER time.

Range: 0 to 12 seconds
Procedure: Adjust the HIGH RESISTANCE ALARM FILTER time to the desired value. Note that

the HIGH RESISTANCE ALARM must be enabled in order to adjust the HIGH RESISTANCE
ALARM FILTER time.

IMPORTANT:

• If an alarm condition appears and then disappears before the alarm filter time has expired,
the filter timer is reset and the alarm condition must exist again for the entire alarm filter
time before the corresponding alarm will be indicated.

• If the user resets an alarm while the alarm condition is still exists, then the alarm will not be
indicated again until the entire alarm filter time has expired.

5.5.16 NOMINAL RESISTANCE SETTING

Purpose: This parameter defines the nominal expected heater resistance. A value must be

entered by the user to allow the HIGH and LOW RESISTANCE ALARMS to be used. In instal­lations where the power source may experience periodic fluctuations (surges and/or brownout
conditions), alarming on resistance deviation offers an improved method of monitoring tracer
integrity than simple LOW and HIGH CURRENT ALARMS. Since the ratio of voltage to current is
monitored, the HIGH and LOW RESISTANCE ALARMS offer cable monitoring that is relatively
immune to voltage fluctuations.

Range: 2.00 to 2000.00 Ω
Procedure: The NOMINAL RESISTANCE value can only be set if either the LOW RESISTANCE

and/or the HIGH RESISTANCE ALARMS are enabled. Once the controller and the heating
cable have been installed, the following procedure should be used to determine the NOMINAL
RESISTANCE

Setting:

• Adjust the CONTROL SETPOINT temperature to turn on the output switch.

• Allow the load to come up to design temperature and its power consumption to stabilize.

• Using the 920 Operator Console, access the RESISTANCE reading and record its value.
Return the CONTROL SETPOINT temperature to its proper setting.

• Enter the recorded resistance value as the NOMINAL RESISTANCE setting.

IMPORTANT: The setup procedure outlined above may have to be repeated a number of times
to arrive at a correct nominal resistance setting. This value will be affected by the heating
cable temperature, which in turn is affected by ambient temperature, insulation level, a full or
empty pipe or vessel, etc.

5.5.17 OVERCURRENT TRIP ALARM (SSR ONLY)

Purpose: The overcurrent trip feature is always enabled when using an SSR output switch and is

used to provide protection for the output switch. Enabling this alarm will only inform the user of an
excessively high current condition and that the output switch has been latched off. During a high
current condition, the controller attempts to soft start a heating cable using a technique involving
measured in-rush current and the SWITCH CURRENT RATING. If the controller is unable to start

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the cable, it will eventually trip its output switch off and will not retry or pulse its output switch
again. At this point the OVERCURRENT TRIP ALARM is latched on.

IMPORTANT:

• The controller is NOT a safety cutout or an overcurrent protective device as defined by the
National and Canadian Electrical Codes (NEC and CEC). A protective device such as a circuit
breaker or fuse must be included as part of a proper design and be selected in accordance
with the requirements defined in the National Electrical Code (NEC) and/or the Canadian
Electrical Code (CEC).

• The controller cannot protect the SSR from short circuits or excessive overcurrent
conditions. Always ensure that the power is off prior to performing any maintenance or
troubleshooting of the heating circuit. Verify that no damage has occurred to the cable or the
controller prior to re-energizing the circuit.

Alarm Mask: ENABLE or DISABLE
Procedure: Adjust the SWITCH CURRENT RATING setting to the actual current rating of the

SSR. Enable or disable the alarm as required. Note that the OVERCURRENT TRIP ALARM does
not have to be enabled in order to adjust the SWITCH CURRENT RATING setting.

IMPORTANT: It is highly recommended that this alarm be left enabled since an overcurrent
trip con- dition would normally represent a serious problem. Note that this is a factory set
alarm value and disabling the alarm does not disable the overcurrent trip function. In some
applications the use of self-regulating cable will produce very high in-rush currents during cold
startup. These currents may exceed the overcurrent trip limit and the controller will not be able
to soft start the trace circuit. If this condition persists please contact your nearest sales office
for recommendations and solutions to this problem.

5.5.18 SWITCH FAILURE ALARM

Purpose: The purpose of the SWITCH FAILURE ALARM is to indicate that an output switch

failure has occurred. The controller determines that if the output switch is turned off and there
is load current present, then the output switch has failed closed and the alarm is latched on.

Alarm Mask: ENABLE or DISABLE
Procedure: Enable or disable the alarming of an output switch that has failed in the closed

position.
IMPORTANT: The SWITCH FAILURE ALARM SHOULD ALWAYS BE ENABLED. A high temperature

condition as a result of a failed circuit can only be caused if the output switch fails closed. When
an output switch fails closed, the controller cannot turn the tracer off; therefore, no protection
features are available (ground fault trip, power limiting, etc.). If a SWITCH FAILURE ALARM is
detected, the unit should be serviced immediately.

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5.5.19 HTC RESET ALARM

Purpose: The HTC RESET ALARM is used to indicate:

1. Power to the HTC has been interrupted and subsequently restored.

2. A transient has caused the HTC’s microprocessor to restart.

3. An internal condition has caused the HTC’s microprocessor to restart its program.

Alarm Mask: ENABLE or DISABLE
Procedure: Enable or disable alarming on reset as desired.
IMPORTANT: Normally the HTC RESET ALARM is left disabled since powering the controller

off and on for maintenance or trouble-shooting would require the user to reset this alarm every
time. If the particular installation includes a Model 780/GCC-9000, this alarm may be left enabled
since resets are not considered normal occurrences and the Model 780/GCC-9000 provides the
capability to easily log and reset alarms such as these. The difference in time between when a
COMMUNICATIONS FAIL ALARM and an HTC RESET ALARM are logged provide an indication of
how long the circuit has been “OFF.”

5.5.20 CIRCUIT BREAKER LIMITING STATUS (SSR ONLY)

Purpose: The circuit breaker limiting feature is always enabled when using an SSR output

switch and is intended to prevent the circuit breaker immediately upstream of the controller
from tripping during a temporary overcurrent condition. Enabling this alarm will only inform the
user that circuit breaker limiting is currently active.

Alarm Mask: ENABLE or DISABLE
Procedure: Adjust the CIRCUIT BREAKER CURRENT RATING setting to the heating circuit

breaker size (i.e. 15.0 or 20.0 Amps). Enable or disable the alarm as required. Note that
the CIRCUIT BREAKER LIMITING ALARM does not have to be enabled in order to adjust the
CIRCUIT BREAKER CURRENT RATING setting.

IMPORTANT:

• This is a non-latching alarm.

• This alarm may be considered an advisory alarm. If the measured current exceeds the level

that would cause the upstream circuit breaker to release, the HTC will begin to switch the SSR
ON and OFF rapidly to limit the average current to an acceptable level.

5-5-21 POWER LIMITING STATUS (SSR ONLY)

Purpose: The power limiting feature is always enabled when using an SSR output switch and is

intended to limit the average amount of power that is applied to the trace circuit. The controller
measures the voltage and current of the tracing circuit and will vary its output switch to limit
the amount of power applied to the trace to the value set by the MAXIMUM POWER setting.
Enabling this alarm will only inform the user that power limiting is currently active.

Alarm Mask: ENABLE or DISABLE
Procedure: Adjust the MAXIMUM POWER setting to the desired value. Enable or disable the

alarm as required. Note that the POWER LIMITING ALARM does not have to be enabled in
order to adjust the MAXIMUM POWER setting.

IMPORTANT:

• This is a non-latching alarm.

• This alarm may be considered more appropriately an advisory alarm and is normally
disabled. It will be active if the MAXIMUM POWER setting is set below the power output level
required for temperature maintenance. In other words, if the circuit demands the maximum
power allowed and the alarm is enabled, then this alarm will be indicated and the output
switch will pulse ON and OFF to limit the average power output to a value approximately
equal to the MAXIMUM POWER setting.

5.5.22 SWITCH LIMITING STATUS (SSR ONLY)

Purpose: The switch limiting feature is always enabled when using an SSR output switch and

is intended to provide protection for the output switch. Enabling this alarm will only inform
the user that switch limiting is currently active and an excessively high current condition is
present. The controller pulses its output switch for a small number of cycles and reads the
resulting current. If the measured current exceeds the SWITCH RATING setting, then the duty­cycle of its output switch will be varied so that an average current not exceed- ing the SWITCH
RATING setting is maintained.

Alarm Mask: ENABLE or DISABLE
Procedure: Adjust the SWITCH CURRENT RATING setting to the actual current rating of the

SSR. Enable or disable the alarm as required. Note that the SWITCH LIMITING ALARM does not
have to be enabled in order to adjust the SWITCH CURRENT RATING setting.

IMPORTANT:

• This is a non-latching alarm.

• This alarm should normally be enabled. Currents in this range cannot be considered normal
and should be investigated.

5.5.23 CONTACTOR COUNT ALARM

Purpose: Generates an alarm if the number of off-to-on transitions of a contactor reaches or

exceeds the CONTACTOR COUNT ALARM setting. This serves as a method to perform pre­ventative maintenance on the contactor before a failure is likely to occur.

Alarm Mask: ENABLE or DISABLE

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5.6 COMMUNICATIONS SETUP

Range: 0 to 999999 off-to-on transitions
Procedure: Adjust the CONTACTOR ALARM setting to the desired value. Note that the CON-

TACTOR ALARM must be enabled in order to adjust the CONTACTOR ALARM setting.
IMPORTANT: The CONTACTOR ALARM is only available if the SWITCH CONTROL MODE is set

to either DEADBAND or PROPORTIONAL AMBIENT CONTACTOR.

5.5.24 EEROM DATA FAILURE ALARM

Purpose: The EEROM DATA FAILURE ALARM indicates that the controller has detected a failure

in its nonvolatile memory.

Alarm Mask: ENABLE or DISABLE
Procedure: Enable or disable alarming of a nonvolatile memory failure as desired.
IMPORTANT: The EEROM DATA FAILURE ALARM should always be enabled. This memory

stores

all of the controller’s configuration and calibration settings and the alarm will only be generated
if the microprocessor cannot bypass the failed area of its memory. This indicates an internal
problem and the 910 should be replaced and returned to the factory for repair.

The following section describes the setup parameters that relate to the way in which the
controller is to communicate with another device. If the optional communications interface is
not installed in the 910 Control Module, these parameters need not be configured.

5.6.1 PROTOCOL

Purpose: Defines the communications language used by the controller to communicate with

other devices.

Setting: HTCBUS™ or MODBUS ASCII or MODBUS RTU
Procedure: Select the HTCBUS™ protocol when communicating with existing PYROTENAX

Heat Trace Control products, including the Model 780/GCC-9000 Group Communications
Controller.

If you are communicating directly with the controller using a different device, select the
MODBUS protocol. For a detailed description of the controller’s MODBUS mapping please refer
to 910 Series Heat Trace Controller—Modbus Protocol Interface document.

5.6.2 HTCBUS ADDRESS

Purpose: Defines the communications address to be used by the controller when using the

HTCBUS™ protocol to communicate with a Model 780/GCC-9000.

Range: 1 to 16,777,215
Procedure: Set the communications address as desired. This must be an address unique to

the entire communications network to avoid messaging conflicts. The HTCBUS™ protocol must
be selected in order to set the HTCBUS™ ADDRESS.

IMPORTANT: A unique HTCBus™ communications address is always assigned by the Factory
and identified by the label on the top of the controller module (see Fig. 2.1). It is recommended
that the pre-assigned address be used whenever possible to minimize the chances of an
address being duplicated in the user’s system.

5.6.3 MODBUS ADDRESS

Purpose: The MODBUS ADDRESS along with the MODBUS SUB ADDRESS define the

communications address to be used by the controller when using either MODBUS protocol to
communicate with a MODBUS compatible device.

Range: 1 to 247
Procedure: Set the communications address as desired. Together with the MODBUS SUB

ADDRESS, this combination must be unique to the entire communications network to avoid
messaging conflicts. Either MODBUS protocol must be selected in order to set the MODBUS
ADDRESS.

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5.6.4 MODBUS SUB ADDRESS

Purpose: The MODBUS SUB ADDRESS along with the MODBUS ADDRESS define the com-

munications address to be used by the controller when using either MODBUS protocol to
communicate with a MODBUS compatible device.

Range: 0 to 31
Procedure: Set the communications sub address as desired. Together with the MODBUS

ADDRESS, this combination must be unique to the entire communications network to avoid
messaging conflicts. Either MODBUS protocol must be selected in order to set the MODBUS
SUB ADDRESS.

IMPORTANT: Since a 910 HTC does not use all 65,535 data registers that are available for
each MODBUS ADDRESS, the data register range is subdivided to allow up to 32 HTCs to share
the same MODBUS ADDRESS. This increases the number of HTCs allowed on a single Modbus
port from 247 to 7,904 (= 247 x 32). This requires that any HTC sharing the same MODBUS
ADDRESS as another HTC must have its own unique MODBUS SUB ADDRESS.

5.6.5 BAUD RATE

Purpose: Defines the data rate at which communications occur.
Setting: AUTO or 9600 or 4800 or 2400 or 1200 or 600 or 300
Procedure: Select the data rate to be compatible with other devices that will be connected to

the controller for communications purposes.
IMPORTANT: Not all communications interfaces will support the various data rates—it is

recommended that the setting be set to AUTO. The controller will automatically select a BAUD
RATE that is compatible with the communications interface installed. If BAUD RATE = AUTO
and a MODEM communication interface is used then a data rate of 300 will always be used.
Otherwise, if BAUD RATE = AUTO and a non-MODEM communication interface is used the
PROTOCOL is either MODBUS protocol then a data rate of 9600 is used.

5.6.6 PARITY (MODBUS)

Purpose: Defines the type of parity bit to be used with MODBUS communications.
Setting: NONE or ODD or EVEN
Procedure: Select the desired type of parity. Note that PARITY can only be selected when using

either MODBUS protocol.

5.6.7 HARDWARE

Purpose: Identifies the type of communications interface installed in the 910. The controller

will automatically determine and display which communications interface type is available.

Values: NONE, MODEM or RS-232 or RS-485

5.6.8 DRIVER

Purpose: Defines the way in which the controller’s program communicates with the com-

munications interface.

Setting: AUTO or RS-232 or RS-485 or MODEM
Procedure: It is recommended that the setting be set to AUTO—this will allow the controller to

automatically choose the setting to match the type of communications interface installed.

5.6.9 PROFILE

Purpose: Defines the way in which the controller’s program supports communications

handshaking and communication interface signals.
Setting: AUTO or
3-WIRE RS-232 or
RS-485 or
1200 BAUD MODEM or
300 BAUD MODEM
Procedure: Select the PROFILE to be compatible with other devices that will be connected to

the controller for communications purposes. It is recommended that the setting be set to

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AUTO. The controller will automatically select a profile based on the type of communications
interface installed in the 910.

IMPORTANT:

• AUTO: Selects a communications profile based on the data rate and the type of communi­cations interface installed in the 910.

• 3-WIRE RS-232: Continuously asserts the internal RTS signal. Internal CTS and DCD signals
are ignored. The Tx Delay timer is active. This is the profile used when PROFILE = AUTO and
an RS-232 communication interface is used with the 910.

• RS-485: Uses the internal RTS signal and the Tx Delay timer. Internal CTS and DCD signals
are ignored. This is the profile used when PROFILE = AUTO and an RS-485 communication
interface is used.

• 1200 BAUD MODEM: Uses the internal RTS signal with a fixed 10 msec Tx Delay time,
ignores the internal CTS signal. Uses the internal DCD signal to qualify each receive data
character. This is the profile used when PROFILE = AUTO, BAUD RATE = 1200 and a MODEM
communication interface is used.

• 300 BAUD MODEM: Uses the internal RTS signal with a fixed 30 msec Tx Delay time, ignores
the internal CTS signal, uses the internal DCD signal to qualify each receive data character.
This is the profile used when PROFILE = AUTO, BAUD RATE is not 1200 and a MODEM
communication interface is used.

5.6.10 TX DELAY

Purpose: Allows a programmable delay between the receipt of a communications message

and the controller’s reply. In some applications, it may be necessary to delay the controller’s
response to an inquiry for a short period of time to allow external devices to start up, stabilize
and/or synchronize.

Range: 0.00 to 2.50 seconds
Procedure: Set the amount of delay between the receipt of a message and the controller’s

response as required.
IMPORTANT: This selectable TX DELAY is only used if the PROFILE is set to either RS-485 or

AUTO and an RS-485 interface is installed.

5.7 OPERATOR CONSOLE FUNCTIONS

The following features are part of the controller’s programming, but are only used in
conjunction with the Operator Console.

5.7.1 PASSCODE

Purpose: The four digit, numeric PASSCODE feature stops unauthorized users from modifying

the controller’s configuration parameters using the Operator Console.

Range: 0000 to 9999
Procedure: Enter the desired PASSCODE (in the “Miscellaneous Common Setup” submenu)

using the Operator Console keypad. A PASSCODE of 0000 disables the lockout feature and
allows all configuration parameters to be modified using the Operator Console without
requiring a PASSCODE. Setting the PASSCODE to any other value will require the database
to be unlocked by entering the correct PASSCODE prior to modifying any of the controller’s
configuration parameters using the Operator Console.

IMPORTANT: The PASSCODE can be edited only if it is set to 0 or the database has been
unlocked by entering the proper PASSCODE.

5.7.2 LOCK DATABASE

Purpose: If the PASSCODE has been enabled (PASSCODE is not set to 0) and the user has unlocked

console modification access to the controller’s configuration parameters, the LOCK DATABASE
feature allows the user to re-lock this modification access once programming has been completed.

Procedure: Select the LOCK DATABASE function (at the end of the “Configuration Mode

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Main Menu”) to lock out Operator Console configuration modification access. The display will
confirm the operation by displaying a “DATABASE LOCKED” message.

IMPORTANT: Operator Console configuration modification access will automatically re-lock
after approximately 5 minutes of keypad inactivity.

5.7.3 UNLOCK DATABASE

Purpose: If a PASSCODE has been enabled (PASSCODE is not set to 0) and the user wants to

modify any of the controller’s configuration parameters using a the Operator Console, then the
database must first be unlocked.

Procedure: Try modifying any configuration parameter, or select the UNLOCK DATABASE
function (at the end of the “Configuration Mode Main Menu”), and a prompt for the PASSCODE
will appear. If the correct PASSCODE is entered then the display will confirm the operation by
displaying a DATABASE UNLOCKED message.

5.7.4 TEST TRACING

Purpose: The TEST TRACING feature provides an easy method of temporarily overriding the

temperature control, without having to modify the CONTROL SETPOINT temperature or any
other configuration parameter.

Procedure: Press the TEST key on the Operator Console or select the TEST TRACING function
to force the output switch on for approximately 30 seconds. After the test time has expired, the
unit will automatically revert back to normal operation.

IMPORTANT:

• This feature only overrides temperature control; it does not override other control parameters
such as power limiting.

• If load shedding is active then TEST TRACING is inhibited.

5.7.5 DISPLAY TEST

Purpose: The DISPLAY TEST feature provides an easy method of illuminating each display

segment and all the LEDs of the Operator Console to ensure that they are functioning properly.
Procedure: Select DISPLAY TEST and watch the Operator Console to verify that each display

segment and each LED is illuminated during the test sequence.
Note: Pressing any key on the Operator Console keypad during the DISPLAY TEST will cause

the DISPLAY TEST to abort.

5.7.6 LOAD DEFAULTS

Purpose: To provide a quick method of setting all of the controller’s configuration parameters

to the factory default configuration parameters, as defined in Appendix G. In additional, all of
the maintenance data parameters are reset. Note that all load shedding parameters (including
fail safe) are configured with default values. The CONSOLE SETPOINT MAXIMUM and
MINIMUM are also configured with default values.

Procedure: Select the LOAD DEFAULTS function (in the “Miscellaneous Setup” submenu) using
the Operator Console keypad.

IMPORTANT: This function will also overwrite the communication configuration parameters,
which could affect existing communications to the controller.

5.7.7 FEATURE MODE

Purpose: Provides two types of menus on the Operator Console for configuring the 910.
Setting: BASIC or ADVANCED
Procedure: Select BASIC if access to only the seven most common parameters is required.

Select ADVANCED if access to all of the 910 parameters is required.

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SECTION 6—MONITORED PARAMETER DETAILS

6.1 INTRODUCTION

The following text provides a brief summary of each of the measured and calculated
parameters that the 910 Series Control Module provides to the user. Detailed information
regarding settings, alarms limits, etc. may be found in Section 5 of this manual.

Detailed information regarding the display of these variables using the Operator Console may
be found in Section 4.2 of this manual.
For detailed information regarding the display of these variables using the Model 780/GCC-

9000, refer to the GCC user manual.

6.2 ANALOG READINGS

6.2.1 CONTROL TEMPERATURE

Purpose: This is the temperature that the controller uses to determine whether its output

switch should be on or off. Depending on the TS CONTROL MODE setting and whether one
or two RTDs are installed, the CONTROL TEMPERATURE may be derived from TS 1 or TS 2, or
a combination of the two temperatures. See Section 5.2.11 of this manual for further details
regarding the TS CONTROL MODE settings.

6.2.2 TS 1 TEMPERATURE

Purpose: This temperature is the value that the controller is reading from the RTD connected

to its TS 1 input. Depending on the TS CONTROL MODE, it may be used to determine the
CONTROL TEMPERATURE (see Section 6.2.1 above).

IMPORTANT: If the TS 1 input is not being used by the controller, the TS 1 TEMPERATURE is
not displayed.

6.2.3 TS 2 TEMPERATURE

Purpose: This temperature is the value that the controller is reading from the RTD connected

to its TS 2 input. Depending on the TS CONTROL MODE, it may be used to determine the
CONTROL TEMPERATURE (see Section 6.2.1 above).

Note: If the TS 2 input is not being used then by the controller then the TS 2 TEMPERATURE is
not displayed.

6.2.4 LOAD CURRENT

Purpose: The LOAD CURRENT reading indicates the average current being drawn by the

heating cable.

6.2.5 RESISTANCE

Purpose: Resistance is calculated using the average adjusted voltage reading divided by the

average adjusted current reading to yield a load resistance in ohms. If the controller’s output
switch is on, but no current is present, the RESISTANCE will read “open circuit.”

IMPORTANT: If the controller’s output switch is off, the RESISTANCE will always display the
last resistance which was calculated while the output switch was last on.

6.2.6 GROUND FAULT CURRENT

Purpose: If the controller detects any leakage current in the output circuit, it will indicate the

level in milliamps.
IMPORTANT: To minimize nuisance alarms, the controller will not report a leakage current of

less than 20 mAmps.

6.2.7 VOLTAGE

Purpose: The voltage reading indicates the average circuit voltage being measured by the 910.

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6.3 MAINTENANCE DATA

6.2.8 POWER

Purpose: Load power provides an indication of the average power being consumed by the heat

trace cable .
IMPORTANT: The controller calculates load power by multiplying the average adjusted voltage

reading by the average adjusted current reading.

6.3.1 MAX / MIN TEMPERATURE VALUES

MAX CONTROL TEMP
MIN CONTROL TEMP
TS 1 MAX TEMP
TS 1 MIN TEMP
TS 2 MAX TEMP
TS 2 MIN TEMP

Purpose: This feature indicates the maximum and minimum temperatures recorded by the
HTC since the last time the values were reset. It may be useful to log the maximum/minimum
temperatures experienced on a particular tracing circuit for the purposes of troubleshooting or
gathering data for future design criteria. The temperature values are written to the controller’s
non-volatile memory once every 24 hours or whenever any maintenance data is reset by the
user. Max/min temperatures are recorded for TS 1, TS 2 and the CONTROL TS.

Range: Can only be reset (cleared) by the operator.
Procedure: The max/min temperatures may be reset using the Operator Console or a

communicating device. Resetting any one of the temperatures will reset all of them.

6.3.2 POWER ACCUMULATOR

Purpose: This feature indicates the total power consumption of the trace circuit since the

last time the POWER ACCUMULATOR was reset. It may be useful to log the amount of power
consumed on a particular trace circuit for the purposes of energy management or gathering of
data for future design criteria. The value of this accumulator is written to the controller’s non­volatile memory once every 24 hours or whenever any maintenance data is reset by the user.

Procedure: The POWER ACCUMULATOR may be reset to zero using the Operator Console or a
communicating device.

IMPORTANT: The POWER ACCUMULATOR value will roll over to zero when the upper limit of
the POWER ACCUMULATOR has been exceeded. This upper limit is 214,748,364.7 kW-hours.

6.3.3 CONTACTOR CYCLE COUNTER

Purpose: This feature indicates the total number of off-to-on transitions a contactor has made

since the last time the CONTACTOR CYCLE COUNTER was reset. This serves as a method
to perform preventative maintenance on the contactor according to the manufacturer’s
specifications. This count value is written to the controller’s nonvolatile memory once every
24 hours or whenever any maintenance data is reset by the user.

Procedure: The CONTACTOR CYCLE COUNTER may be reset to zero using the Operator
Console or a communicating device.

IMPORTANT:

• Once the CONTACTOR CYCLE COUNTER reaches 999,999,999 it will stop counting.

• The CONTACTOR CYCLE COUNTER is only indicated if the SWITCH CONTROL MODE is set
to either DEADBAND or PROPORTIONAL AMBIENT CONTACTOR.

6.3.4 TIME IN USE

Purpose: The purpose of this feature is to indicate the total hours in use of the controller since

its initial operation. It may be useful to log the amount of time a particular controller has been
in operation for the purposes of maintenance planning or reliability testing. The value of this
accumulator is written to the controller’s nonvolatile memory once every 24 hours or whenever
any maintenance data is reset by the user.

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Procedure: The IN USE hours accumulator can be reset to zero using the Operator Console or
a communicating device.

IMPORTANT: The IN USE hours accumulator value will roll over to zero when the upper limit of
the accumulator has been exceeded. This limit is 999,999,999 hours.

6.3.5 TIME SINCE LAST RESET

Purpose: This feature indicates the total hours in use of the controller since the last reset.

It may be useful to log the amount of time a particular controller has been in operation since
the last time the controller’s power was cycled for trouble-shooting purposes.

Procedure: The TIME SINCE LAST RESET hours accumulator can only be reset by cycling the
controller’s power.

Note: The TIME SINCE LAST RESET will roll over to zero when the upper limit of 65,535 hours
has been exceeded.

6.3.6 PEAK LOAD CURRENT

IMPORTANT: The PEAK LOAD CURRENT is not displayed on the Operator Console.
Purpose: This feature indicates the highest instantaneous load current measured since the last

time the PEAK LOAD CURRENT was reset. This value is written to the controller’s nonvolatile
memory once every 24 hours or whenever any maintenance data is reset by the user.

Procedure: The PEAK LOAD CURRENT may only be reset to zero using a communicating device.

6.3.7 PEAK GROUND FAULT CURRENT

IMPORTANT: The PEAK GROUND FAULT CURRENT is not displayed on the Operator Console.
Purpose: This feature indicates the highest instantaneous ground fault current measured since

the last time the PEAK GROUND FAULT CURRENT was reset. This current value is written to
the controller’s non-volatile memory once every 24 hours or whenever any maintenance data is
reset by the user.

Procedure: The PEAK LOAD CURRENT may only be reset to zero using a communicating
device.

6.3.8 EXTERNAL INPUT STATUS

IMPORTANT: The EXTERNAL INPUT STATUS is not displayed on the optional Operator

Console.
Purpose: This feature indicates the actual status of the external input regardless of the

controller’s configuration. This may be useful if the user wishes to use the controller’s external
input to monitor the status of an external dry contact and pass this on to another device.

Procedure: The EXTERNAL INPUT STATUS may only be viewed using a communicating device.

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SECTION 7—CONTROL MODES

7.1 INTRODUCTION

7.2 SWITCH CONTROL MODES

There are several different types of control modes in the controller. Some of these modes
require further explanation in order to fully understand and implement their operation.

This section describes the control modes available in the HTC and how to set their associated
parameters.

There are four different SWITCH CONTROL modes associated with the HTC. The following is
an explanation of their implementation in the controller and the differences between them.

7.2.1 PROPORTIONAL CONTROL (FOR USE WITH SSRS ONLY)

Proportional control on the HTC is implemented as follows:

• When using SSRs to directly control the power applied to a trace circuit, the output may be
switched on/off very rapidly. The controller implements proportional temperature control on
a cycle by cycle basis (50 or 60 Hz power line cycle).

• This algorithm monitors the temperature of the heating circuit and compares it to the
CONTROL SETPOINT temperature. If the temperature of the control sensor is at or below
the CONTROL SETPOINT temperature, then power is applied to the trace with a duty cycle of
100%—the controller output is full on.

• If the temperature sensed by the control sensor is equal to or greater than the CONTROL
SETPOINT temperature + the PROPORTIONAL BAND setting, then the controller output will
have a duty cycle of 0%—the output will be off.

• The temperature of the control sensor is constantly monitored and the output duty cycle is
adjusted proportionally according to where the temperature falls within the 0%–100% band.

Proportional Control Temperature Band

Control Sensor Temperature Duty Cycle

Setpoint + proportional band 0%

Setpoint + proportional band/2 50%

Setpoint 100%

7.2.2 DEADBAND CONTROL (FOR USE WITH EXTERNAL CONTACTORS)

Deadband control on the HTC is implemented as follows:

• When using the HTC in an application where the controller is used to open and close a contactor,
proportional control cannot be used since this would cycle the contactor too quickly. In these
situations, a deadband control algorithm is used. The output duty cycle is not controlled, instead
the output is either fully on or completely off. The user may set the DEADBAND value.

• The controller monitors the temperature of the trace circuit and compares it to the
CONTROL SETPOINT temperature as in the proportional control mode. If the control sensor
temperature is above the CONTROL SETPOINT temperature by more than the DEADBAND
value, the output is turned off.

• If the control sensor temperature falls below the CONTROL SETPOINT temperature the
output is turned on.

This is a very simple control algorithm but it works very effectively in heat trace applications
where the temperature of a traced system changes relatively slowly.

Deadband Control Temperature Band

Control Sensor Temperature Output State

Setpoint + deadband Off

Setpoint On

When the control sensor temperature is within the deadband, the output does not change its
state. Also, when using deadband control, a contactor is not allowed to toggle faster than every
two seconds. If an AC alarm with an alarm filter time greater than 0 is detected, the contactor
will not toggle until the alarm filter time has expired.

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7.2.3 PROPORTIONAL AMBIENT SSR CONTROL (FOR USE WITH SSRS ONLY)

When an HTC using an SSR is used to control the output using the ambient temperature, this
control mode should be used.

Proportional ambient SSR control on the HTC is implemented as follows:

• When using SSRs to directly control the power applied to a heating circuit, the output may be
switched on/off very rapidly. The controller implements proportional temperature control on
a cycle by cycle basis (50 or 60 Hz power line cycle).

• This algorithm monitors ambient temperature and compares it to the CONTROL SETPOINT
temperature. If the temperature of the control sensor is at or below the CONTROL SETPOINT
temperature minus the PROPORTIONAL BAND setting, then power is applied to the trace
with a duty cycle of 100%—the controller output is fully on.

• If the temperature sensed by the control sensor is equal to or greater than the CONTROL
SETPOINT temperature, then the output will have a duty cycle of 0%—the controller output
will be off.

• The temperature of the control sensor is constantly monitored and the output duty cycle is
adjusted proportionally according to where the temperature falls within the 0%–100% band.

Proportional Ambient SSR Control Temperature Band

Control Sensor Temperature Duty Cycle

Setpoint 0%

Setpoint - proportional band/2 50%

Setpoint - proportional band 100%

IMPORTANT: The load shedding “fail safe mode” is not supported when using proportional
ambient SSR control, since ambient temperature is being monitored rather than pipe
temperature.

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7.2.4 PROPORTIONAL AMBIENT CONTACTOR CONTROL (FOR USE WITH

CONTACTORS)

When an HTC using a contactor is used to control the output based on the ambient
temperature, this control mode should be used.

Proportional ambient contactor control on the HTC is implemented as follows:

• The output may not be switched on/off rapidly when using a contactor, so proportional
temperature control is implemented by applying the required duty cycle over the selected
CYCLE TIME.

• The output is fully on for a portion of the CYCLE TIME as determined by the calculated duty
cycle, and it will be completely off for the remainder of the CYCLE TIME.

• The duty cycle is calculated each time the output toggles, based on the ambient temperature,
PROPORTIONAL BAND setting, and the CONTROL SETPOINT temperature setting.

• The controller monitors the ambient temperature and compares it to the CONTROL
SETPOINT temperature as in proportional ambient SSR control. If the temperature
of the control sensor is at or below the CONTROL SETPOINT temperature minus the
PROPORTIONAL BAND setting, then power is applied to the trace with a duty cycle of 100%.
The controller output will be fully on for 1/30 of the CYCLE TIME setting before the duty
cycle is calculated again.

• If the temperature sensed by the control sensor is equal or greater than the CONTROL
SETPOINT temperature, then the output will have a duty cycle of 0%. The controller output
will be off for 1/30 of the CYCLE TIME setting before the duty cycle is calculated again.

Proportional Ambient Contactor Control Temperature Band

Control Sensor Temperature Duty Cycle

Setpoint 0%

Setpoint - proportional band/2 50%

Setpoint - proportional band 100%

IMPORTANT: The load shedding “fail safe mode” is not supported when using proportional
ambient contactor control, since ambient temperature is being monitored rather than pipe
temperature. Also note that if an AC alarm, with an alarm filter time greater than 0, is detected
the contactor will not toggle until the alarm filter time has expired.

7.3 LOAD SHEDDING CONTROL MODE

Load shedding is a control mode that may be programmed and initiated only by an external
communicating device or by the Model 780/GCC-9000 Group Communications Controller,
which overrides temperature control and forces the output of the controller OFF until reset
by the 780/GCC-9000. When using a GCC, load shedding is initiated by a contact closure (or
opening) on one of the four contact inputs on the GCC. Each contact input initiates a load
shedding command for the group of controllers associated with that contact input. Each
controller may be associated with one or more groups. Refer to the Load Shedding Section in
the GCC manual for details on setting up the load shedding features of the HTC when using a
GCC.

When power is applied to the controller, it determines if load shedding mode has been enabled.
If enabled, the controller immediately enters load shedding operation (holding its output off)
and waits to see if the GCC or an external communicating device has initiated a load shedding
command. If no command is present, the controller resumes normal operation. If a load
shedding command is present, the controller will continue to hold its output OFF, until one of
three conditions occurs:

1. The GCC contact input or zone definition bits of an external communicating device that

initiated load shedding clears and the command to terminate load shedding mode is issued.

2. Communications are interrupted between the controller and its communicating device

(as in the case of a damaged communications wire). Approximately 30 seconds after
communications ceases, the controller will return to normal operation.

3. Communications between the controllers and the external communicating device go offline

for approximately two minutes (as occurs when the 760 Hand Held Programmer is used to
communicate with the controller).

IMPORTANT: The controller will return to normal operation if communications between the
GCC or external communicating device and the controller is disrupted in any way. This will
return temperature control to the HTC. Also, the HTC does not perform a periodic autocycle
test while operating in load shed mode. When using a GCC it must be configured for load
shedding operation before the controller may be set up for load shedding control.

There are three parameters that must be set up in the controller to completely configure it for
load shedding operation:

1. The load shedding feature must be enabled.

2. The FAIL SAFE MODE parameter must be enabled or disabled depending on the application

requirements. If FAIL SAFE MODE is enabled, then at least one LOW TS ALARM (of a TS used
in the TS CONTROL MODE) must be enabled and its alarm temperature must be less than
the CONTROL SETPOINT temperature; otherwise, fail safe mode will be disabled.

3. The GCC contact input(s) or zone definition bits of an external communicating device that

are to be associated with the load shedding action for the controller must be defined.

These parameters may only be configured using an external communicating device or the
Model 780/GCC-9000 Group Communications Controller. Refer to the Model 780/GCC-9000
user manual for details on how to set up these options. Note that the Operator Console may be
used to enable or disable the load shedding feature but not set any of the other load shedding
parameters.

IMPORTANT:

• Fail safe mode is always disabled if the SWITCH CONTROL MODE is set to either of the two

proportional ambient control modes, or the TS CONTROL MODE = EXT. INPUT, FAIL OFF/ON.

• If the TS CONTROL MODE uses both TS 1 and TS 2 to calculate the control temperature, the

HTC will turn on its output if the following conditions are met:
– load shedding is active
– fail safe mode is enabled
– the control temperature falls below either of the LOW TS ALARM settings
– both TS 1 and TS 2 have their LOW TS ALARMS enabled

• A FORCE ON override signal has higher priority than a load shedding signal. An INHIBIT

signal has higher priority than fail safe mode.

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SECTION 8—TROUBLESHOOTING

8.1 OPERATOR CHECKS

IMPORTANT: If the controller does not operate properly and is being returned to nVent for

service, information must be provided as to why the unit was removed from service. Contact
the nVent customer service department for a Return Authorization form and number prior to
returning any units for repair.

Upon receipt of the controller, or to check the controller for an indication of normal operation,
follow the operational procedures shown below. These procedures are designed to familiarize
the operator with the controller and to provide an understanding of its operation.

In order to determine if a fault is associated with the heat tracing, wiring or the controller, it
will be necessary to troubleshoot the wiring and tracer circuit. If the fault remains, remove
power from the controller and exchange it with another controller. This may require some
reprogramming of the new HTC. Refer to the following sections for the appropriate topic.

If the fault clears, exchange the controller on another circuit to determine if the fault moves
with the controller. If the fault moves with the controller, verify that the HTC has been
configured correctly for the application. If the configuration is correct it may be necessary to
return the controller to nVent for evaluation.

8.1.1 GETTING STARTED

In order to access the functions of the 910 Series HTC, use the Operator Console. If the
modem communications option is installed in the 910, the Model 780/GCC-9000 Group
Communications Controller may also be used to access controller parameters. Refer to the
GCC User Manual for operational details.

8.2 COMMON PROBLEM AREAS

The HTC may be used as an effective troubleshooting tool to pinpoint problem areas of heat
trace circuits. Described below are a few of the more common problem areas, their symptoms,
and parameters to check to determine the actual faulty portion of the heat trace circuit.

8.2.1 RTDS

RTD failures after installation can generally be attributed to incorrect wiring or improper
installation of the sensor. Troubleshooting of these failures is a very simple procedure if the
proper steps are undertaken in the correct order. Some specific RTD problems and the correct
methods for troubleshooting are outlined as follows.

1. TS Failure Alarm(s)

If the HTC controller indicates a failure of an RTD:

• Ensure that the RTD is a 3-wire 100 ( Platinum Type (for V3.00). For V3.11 and up ensure that

the TS TYPE setting matches the RTD being used.

TURN THE POWER TO THE CONTROLLER OFF BEFORE PROCEEDING!!

• Disconnect the RTD wiring from the input terminals.

• Measure the RTD’s resistance between the source (WHT) and sense (WHT) leads at the

controller (it should not exceed 40 Ω). Excessive lead resistance will cause a TS FAILURE
ALARM and must be corrected. Look for loose terminals, excessive lead length, or
insufficient wire gauge and correct as necessary.

• Measure the RTD’s resistance between the source (WHT) or sense (WHT) lead and the

common (RED) lead of the RTD at the controller (should be between 60 and 330 Ω depending
on the temperature and the lead resistance. See Appendix E or Appendix F).

• Verify that the RTD is wired correctly—the heat tracing controllers will always be terminated

in the order: source (WHT), sense (WHT), common (RED). When wiring to the 910, the
terminals are marked as follows:

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Terminal No. Description

19 Shield

20 TS 1 Source (WHT)

21 TS 1 Sense (WHT)

22 TS 1 Common (RED)

8 Shield

9 TS 2 Source (WHT)

10 TS 2 Sense (WHT)

11 TS 2 Common (RED)

The RTD manufacturer will typically color code the leads with the source and sense being the
same color, and the common a different color. Ensure that the RTD extension wire shield is
terminated at one end only, normally using the terminal block provided at the terminal board.

IMPORTANT: Some manufacturers use the common Black-White-Red triad color code for the
RTD connections. Usually, the RED lead is the common connection (same as the White-white
Red color scheme) and the White and Black connections may be used interchangeably.

2. Seemingly Incorrect Temperature

If you feel that the indicated or displayed temperature is not correct, the controller and the
RTD can be quickly checked for correct operation.
To verify the RTD:
TURN THE POWER TO THE CONTROLLER OFF BEFORE PROCEEDING!!

• Disconnect the RTD wiring from the input terminals.

• To calculate the temperature indicated by the RTD, measure the resistance from source

(white wire) or sense (white wire) to common (red wire) and subtract the resistance
measured between source and sense. This will give a compensated resistance value that
can be cross-referenced to one of the RTD tables found in Appendix E or Appendix F.

Compare the measured resistance and cross-referenced temperature value obtained from
the RTD table to the indicated or displayed value. These should agree to within the accuracy
standards of the HTC and the RTD.

IMPORTANT:

• Ensure you refer to the correct RTD table for the type of RTD you are using.

• Ensure that the TS TYPE setting matches the type of RTD that you are using.
To verify the Controller:
TURN THE POWER TO THE CONTROLLER OFF BEFORE PROCEEDING!!

• Disconnect the RTD wiring from the input terminals.

• Connect a 100 Ω resistor across the source or sense terminal and common. Insert a jumper

between the source and sense terminals.

• Apply power to the controller. The indicated or displayed temperature should be about 32°F (0°C)

depending on the actual resistance of the test resistor if TS TYPE is set to 100 Ω Platinum.

3. Unstable or Bouncing Temperature

An erratic indication of temperature can be caused by several factors external to the
controller, however a bouncing temperature of a few degrees should not be confused with
incorrect operation. The controller’s accuracy and resolution will result in an indicated
temperature change of a couple of degrees if the measured resistance temperature falls
between two discrete values (this is sometimes referred to as quantization error).

If the bounce or instability is excessive, check:

• Wire used for extension of the RTD should be three-wire, twisted and shielded with the shield

• The ideal installation has a separate conduit for the RTD leads (if they have been extended).

grounded at the controller only. Each of the three lead wires must be of the same gauge.

It is not usually a problem to run low signal levels in the same conduit as the power leads
even in high power applications, as long as the RTD wire is a twisted, shielded type with an
insulation rating equal to or greater than the highest voltage in the conduit.

nVent.com | 55

Follow the proper Electrical Code requirements for your particular installation.

• Terminal connections that are not tight can add resistance to an RTD circuit. Check the

tightness of all screw terminal connections at time of installation and during subsequent

maintenance checks.

• Check the specifications for the particular cable being used to ensure that it does not have

excessive capacitance when used in long lengths. This can cause a temperature offset

between what the controller reads and what the RTD actually measures. This again is

normally not a problem since the controller compensates for all but the worst cases of this.

• Lastly, it is possible for the RTD itself to fail on an intermittent basis but this failure mode

should be considered unusual. This kind of failure is probably the most difficult to find but

fortunately it is also the least likely as a failure mechanism.

8.2.2 GROUND FAULT

Ground fault alarms can be due to incorrect installation as well as leakage resulting from wet
system components or faulted cables.

The 910 Series Controller detects ground faults by summing the outgoing and return trace
currents through an internal current transformer. Under normal operating conditions
(no ground fault condition) this current will be zero. When there is a flow of current from one of
the trace supply wires to ground, a ground fault condition occurs.

If a ground fault alarm is present on start-up of a new installation it is likely due to a wiring
error or damaged cable. To verify this condition:

• Check that the heating circuit neutrals return to the controller and are not connected directly to

the distribution panel. This can be a common problem if the installation is a retrofit situation.

• On paralleled circuits, be certain that ALL neutrals return. The late addition of a circuit may

not be obvious.
Use the monitoring feature available at the 910 Operator Console or the Model 780/GCC-9000

Group Communications Controller to view the measured ground fault current at the heat
trace controller. If this value is at the maximum that the controller can measure, it is usually
an indication that the wiring is incorrect. If the value is less than 250 mAmps then an actual
ground fault condition may exist in the cable.

IMPORTANT: The controller monitors the integrity of the ground fault (GF) detection transformer
and associated wiring. If a fault is detected, the controller will report a GF value of 300 mAmps.

8.3 COMMON ALARMS—WHAT TO LOOK FOR

The 910 has a wide range of alarming features that may be selectively enabled or disabled to
allow the monitoring and indication of trouble conditions. Described below are the different
alarm conditions available on the 910, their meanings, and possible causes.

8.3.1 High TS 1/ TS 2 Temperature

This alarm appears when the temperature exceeds the HIGH TS ALARM temperature setting.

Cause of Alarm:

• Alarm temperature setting too close to maintain temperature

• Flow of hot product

• Steaming out lines

• Incorrect tracer wiring

8.3.2 LOW TS 1/TS 2 TEMPERATURE

This alarm appears when the temperature decreases below the LOW TS ALARM
temperature setting.

Cause of Alarm:

• Alarm temperature setting too close to maintain temperature

• Flow of cold product

• Empty pipe

• Damaged, wet, or missing insulation

56 | nVent.com

• Heating cable not sized properly for the application

8.3.3 TS 1/ TS 2 FAILURE

This alarm indicates a sensor is not operating properly. The temperature sensor may fail due to
an “open” or “shorted” condition.

Cause of Alarm:

• Incorrect or damaged field wiring—open leads or excess resistance (either intermittent or

continuous) may be due to broken or damaged wires or loose terminals.

• Damaged or inoperative temperature sensors

8.3.4 CONTROL TS FAILURE

This alarms a failure of the temperature sensing element designated as the control element
by the TS CONTROL MODE setting. Depending on the chosen TS FAIL MODE and TS CONTROL
MODE, the output switch may be latched off or on until this failure is corrected.

Cause of Alarm:

• Incorrect or damaged field wiring—open leads or excess resistance (either intermittent or

continuous) may be due to broken or damaged wires or loose terminals.

• Damaged or inoperative temperature sensors

8.3.5 HIGH CURRENT

This alarms current levels that are greater than the HIGH CURRENT ALARM setting for the
application.

Cause of Alarm:

• Alarm setting too close to normal operating current

• High in-rush current from “cold start” of self regulating cable

• Damaged or partially shorted heating cable

• “As built” cable length is greater than design value

8.3.6 LOW CURRENT

This alarms current levels which are less than the LOW CURRENT ALARM setting.

Cause of Alarm:

• Alarm setting too close to normal operating current

• Low source voltage

• Damaged or inoperative heating cable

• Open connection—wiring problem

• SSR or contactor failed open

8.3.7 HIGH GFI

This alarms ground fault current levels which are greater than the HIGH GFI ALARM setting.

Cause of Alarm:

• Alarm setting too close to normal leakage current

• Damaged cable insulation and/or moisture present

• Moisture in junction box

• Poor splice or termination

• Moisture provides conductive ground path which allows ground fault current

8.3.8 GFI TRIP

This value sets the upper limit of allowable ground fault leakage. Exceeding this limit will result in
the output switch being latched off and the alarm activated to indicate a ground fault condition.

Cause of Alarm:

• Trip setting too close to normal leakage current

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• Damaged cable insulation and/or moisture present

• Moisture in junction box

• Poor splice or termination

• Moisture provides conductive ground path which allows ground fault current

8.3.9 HIGH VOLTAGE

This alarms voltage levels that are greater than the HIGH VOLTAGE ALARM setting.

Cause of Alarm:

• Alarm setting too close to normal operating voltage

• Incorrect wiring

• Power surge

8.3.10 LOW VOLTAGE

This alarms voltage levels which are less than the LOW VOLTAGE ALARM setting.

Cause of Alarm:

• Alarm setting too close to normal operating voltage

• Damaged power cable

• Incorrect VOLTAGE TURNS RATIO

• “Brown-out” conditions

• Loss of power to the circuit

8.3.11 OVERCURRENT TRIP

If the controller is unable to start the cable due to high current or after attempting to soft start
it, the controller will trip its output switch off.

Cause of Alarm:

• Excessive in-rush current

• Incorrect wiring

• Damaged cable

8.3.12 SWITCH FAILURE

This alarm indicates that the controller senses current flow when the output switch should be
off.

Cause of Alarm:

• Some other device energized heat trace

• Output switch has failed “closed”

8.3.13 HTC RESET

This alarm is latched when power is restored after an interruption. Used to identify intermittent
power losses.

Cause of Alarm:

• Circuit breaker tripped

• Power line transient

8.3.14 POWER LIMITING

This alarm indicates that the solid state relay is limiting the average amount of power that is
applied to the trace circuit as defined by the MAXIMUM POWER setting.

Cause of Alarm:

• Power applied to trace circuit is being limited to the MAXIMUM POWER setting

8.3.15 C.B. LIMITING

This alarm indicates that the solid state relay is limiting the average current that is applied to
the trace circuit to the C.B. CURRENT RATING setting to protect the upstream heater circuit
breaker from tripping.

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Cause of Alarm:

• Excessive current caused by in-rush current

• C.B. CURRENT RATING setting too low for normal heater current draw or not matched to

actual circuit breaker size

8.3.16 SWITCH LIMITING

This alarm indicates that the controller is limiting the average current that is applied to the
trace circuit based on the SWITCH RATING setting to protect the solid state relay from
excess current.

Cause of Alarm

• Excessive current caused by in-rush current

• Excessive ambient temperature

8.3.17 HIGH RESISTANCE

This alarm indicates that the heating cable resistance has deviated from the NOMINAL
RESISTANCE setting by more than the HIGH RESISTANCE ALARM setting.

Cause of Alarm

• Alarm setting too close to actual operating resistance

• NOMINAL RESISTANCE not set properly

• Open connection—wiring problem

• Damaged cable

8.3.18 LOW RESISTANCE

This alarm indicates that the heating cable resistance has deviated from the NOMINAL
RESISTANCE setting by more than the LOW RESISTANCE ALARM setting.

Cause of Alarm

• Alarm setting too close to actual operating resistance

• NOMINAL RESISTANCE not set properly

• Partial short—wiring problem

• Damaged cable

8.3.19 EEROM DATA FAILURE

This alarm indicates that the controller has detected a failure in its nonvolatile memory (this is
where all of the controller’s configuration and calibration settings are stored). This indicates an
internal problem and the HTC should be replaced and returned to the factory for repair.

Cause of Alarm:

• The HTC cannot bypass the failed area of its memory and has loaded factory defaults into

this failed area.

8.3.20 CONTACTOR COUNT

This alarm indicates that the number of off-to-on transitions of a contactor has exceeded the
CONTACTOR COUNT ALARM setting and the contactor should be replaced.

Cause of Alarm

• Contactor has been controlling the trace circuit for a long time

• Some configuration parameter (i.e. DEADBAND, AUTO CYCLE INTERVAL, load shedding etc.)

is causing the contactor to toggle more than usual.

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SECTION 9—MAINTENANCE

9.1 OPERATOR MAINTENANCE

9.2 REPLACEABLE PARTS

The 910 series controller is designed to be a maintenance-free product. Once installed properly
the only maintenance required is retightening of the terminal connections approximately
one week after installation and inspection periodically thereafter. Also, alarm pilot lamps
(if installed) may need periodic replacement. EMR versions may require periodic contactor
replacement.

CAUTION:

Make sure that the power to the controller is OFF when replacing the pilot lamps! Also, be
certain power is OFF to the controller before attempting to test or service the heat tracing.
Do not rely on the controller as a disconnect device!

There are no user-serviceable parts in the 910 series controller or accessories (except lamps
in optional alarm pilot lights). The unit is designed to be modular and easily changed out in
the field in a matter of minutes. A 910 appearing inoperative should be returned to the nearest
nVent Service Center for service.

WARNING:

Tampering with the 910 components without approval from nVent could result in the product’s
warranty being void.

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APPENDIX A—SPECIFICATIONS

Specifications are @ 25°C unless otherwise noted and are subject to change without notice.

System Ratings

Storage Ambient –40°F to 185°F (–40°C to 85°C) Approvals CSA C/US
Classification • Cl I, Div 2, Grps A,B,C,D and Ex nA IIA, IIB, IIC (Zone 2)

• SSR Version T-code: T4

• Ordinary locations (SSR and EMR versions)

Wiring Terminal Ratings

Signal Terminals 28-12 AWG, strip length: 0.2”
Power Terminals 30A: 22-8 AWG, strip length: 0.47”, torque: 10.7 in-lb

(1.2 N-m)
Ground Lugs 14-6 AWG torque: 12 in-lb (1.35 N-m)

Assembly Ratings

Operating Temperature –40°F to 140°F (–40°C to 60°C) Enclosures FRP: Nema 4X/IP65
SS: Type 304, Nema 4X/IP65

Solid State Relay Rating • 2 pole switching

• 30 A continuous @ 40°C, derate linearly to:

  15Amax.@60°C
  resistiveload

• 100–277 Vac nom. max., 80 A 1 sec. in-rush, 625 A 1 cycle in-rush
Electromechanical • 2 pole switching

Relay Rating • 30 A continuous @ 40°C derate linearly to:
  20Amax.@60°C

• 100–277 Vac nom. max.

Control Module Ratings

Operating Temperature –40°F to 140°F (–40°C to 60°C)
Power Requirements 100 to 277 Vac nom., 1PH, 50/60 Hz, 0.2A. max. + 0.75A

(Aux. AC output terminals)
Output Power +12Vdc nom., 250ma. max.
Control Modes • Proportional, Deadband, Proportional Ambient (SSR),

  ProportionalAmbient(Contactor)modes

• Adjustable 2°F to 90°F (1°C to 50°C)

TemperatureInputs (2)RTDinputs:3-wire100ΩPlatinum(DIN43760,α=0.00385Ω/Ω/°C)
 or2/3-wire100ΩNi-Fe,open/shortedsensordetection/protection,
 leadresistancecompensated0to20Ωperlead

Temperature –76°F to 1058°F (–60°C to 570°C), accuracy ± 0.5% of
Measurement Range span ± 1LSD

Voltage 80 to 295Vac, accuracy: ± 1% of span ± 2LSD,
Measurement Range repeatability: ± 1.5% of span

Current 0.3 to 100A, resolution: 0.1A (0.3A to 11A range),
Measurement Range 0.3A (11A to 40A range), 0.7A (40A to 100A range),
accuracy: ± 2.5% of reading ± resolution

GF Current 20 to 250ma, accuracy: ± 2.5% of span ± 2LSD at nominal load,
Measurement Range repeatability: ±4% of span

Dry Contact 48Vac/dc, 500ma, 10VA switching max.
Alarm Relay Output

AC Alarm Relay Output 0.75A, 100–277 Vac nom. max.

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APPENDIX B—TYPICAL ENCLOSURE DIMENSIONS

The following drawings provide the user with enclosure size and mounting dimensions for
the stock 910 enclosure assemblies. Please contact your local nVent representative for
information regarding other available sizes and configurations.

B.1 STANDARD FIBERGLASS EMR ASSEMBLY #10170-001

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B.2 OPTIONAL STAINLESS STEEL EMR ASSEMBLY #10170-003

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B.3 STANDARD FIBERGLASS SSR ASSEMBLY #10170-0002

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B.4 OPTIONAL STAINLESS STEEL SSR ASSEMBLY #10170-004

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B.5 910 SERIES HTC CONTROL MODULE DIMENSIONS

for a #8 machine screw

D910 SERIES

66 | nVent.com

Mounting slots suitable

APPENDIX C—WIRING DIAGRAMS

The following drawings provide sample wiring diagrams for the 910 Series control products
and optional accessories. Please contact your local nVent representative for information
regarding other available options.

C.1 TS WIRING

Note: Temperature sensor manufacturers may use different lead wire colors than those shown

in the diagram above. Some common color combinations are shown in the table below, but
others may also be available. See Sections 2.7.1 and 8.2.1 for additional details.

Lead Wire Lead Wire Lead Wire
Signal Description Color Scheme #1 Color Scheme #2 Color Scheme #3 (IEC 751)

Source White White Red
Sense White Black Red
Common Red Red White

C.2 POWER WIRING

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C.3.1 2-WIRE MODEM OPTION

C.3.2 2-WIRE RS-485 OPTION

C.4 ALARM OUTPUT WIRING

C.3.3 RS-232 OPTION

C.4.1 USED AS A DRY CONTACT

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C.4.2 USED AS A SWITCHED DC CONTACT

C.4.3 USED AS AN AC ALARM RELAY

C.4.4 Used as a Powered AC Alarm Relay

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C.5 EXTERNAL INPUT/OUTPUT PORT WIRING

C.5.1 EXTERNAL INHIBIT/OVERRIDE USING A DRY CONTACT

C.5.2 EXTERNAL INHIBIT/OVERRIDE USING A DC SIGNAL

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APPENDIX D—HTC LOAD SHEDDING SEQUENCE

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APPENDIX E—100 Ω PLATINUM RTD TABLE

DIN 43760—100 Ω PLATINUM RESISTANCE TEMPERATURE (RTD)—0.00385 OHMS/OHM/°C

Ohms °C °F Ohms °C °F Ohms °C °F

60.25 -100 -148 159.18 155 311 250.48 410 770

62.28 -95 -139 161.04 160 320 252.19 415 779

64.30 -90 -130 162.90 165 329 253.90 420 788

66.31 -85 -121 164.76 170 338 255.61 425 797

68.33 -80 -112 166.61 175 347 257.32 430 806

70.33 -75 -103 168.46 180 356 259.02 435 815

72.33 -70 -94 170.31 185 365 260.72 440 824

74.33 -65 -85 172.16 190 374 262.42 445 833

76.33 -60 -76 174.00 195 383 264.11 450 842

78.32 -55 -67 175.84 200 392 265.80 455 851

80.31 -50 -58 177.68 205 401 267.49 460 860

82.33 -45 -49 179.51 210 410 269.18 465 869

84.27 -40 -40 181.34 215 419 270.86 470 878

86.25 -35 -31 183.17 220 428 272.54 475 887

88.22 -30 -22 184.99 225 437 274.22 480 896

90.19 -25 -13 186.82 230 445 275.89 485 905

92.16 -20 -4 188.63 235 455 277.56 490 914

94.12 -15 5 190.45 240 464 279.23 495 923

96.09 -10 14 192.26 245 473 280.90 500 932

98.04 -5 23 194.07 250 482 282.56 505 941

100.0 0 32 195.88 255 491 284.22 510 950

101.95 5 41 197.69 260 500 285.87 515 959

103.90 10 50 199.49 265 509 287.53 520 968

105.85 15 59 201.29 270 518 289.18 525 977

107.79 20 68 203.08 275 527 290.83 530 986

109.73 25 77 204.88 280 536 292.47 535 995

111.67 30 86 206.67 285 545 294.11 540 1004

113.61 35 95 208.45 490 554 295.75 545 1013

115.54 40 104 210.24 295 563 297.39 550 1022

117.47 45 113 212.02 300 572 299.02 555 1031

119.40 50 122 213.80 305 581 300.65 560 1040

121.32 55 131 215.57 310 590 302.28 565 1049

123.24 60 140 217.35 315 599 303.91 570 1058

125.16 65 149 219.12 320 608 305.53 575 1067

127.07 70 158 220.88 325 617 307.15 580 1076

128.98 75 167 222.65 330 626 308.76 585 1085

130.89 80 176 224.41 335 635 310.38 590 1094

132.80 85 185 226.17 340 644 311.99 595 1103

134.70 90 194 227.92 345 653 313.59 600 1112

136.60 95 203 229.67 350 662 315.20 605 1121

138.50 100 212 231.42 355 671 316.80 610 1130

140.39 105 221 233.17 360 680 318.4 615 1139

142.29 110 230 234.91 365 689 319.99 620 1148

144.17 115 239 236.65 370 698 321.59 625 1157

146.06 120 248 238.39 375 707 323.18 630 1166

147.94 125 257 240.13 380 716 324.76 635 1175

149.82 130 266 241.86 385 725 326.35 640 1184

151.70 135 275 243.59 390 734 327.93 645 1193

153.58 140 284 245.31 395 743 329.51 650 1202

155.45 145 293 247.04 400 752 331.08 655 1211

157.31 150 302 248.76 405 761 332.66 660 1220

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APPENDIX F—100 Ω NICKEL-IRON RTD TABLE

Ohms °C °F Ohms °C °F Ohms °C °F

69.8 -73 -100 133.4 68 155 218.2 210 410

71.1 -70 095 134.8 71 160 220.1 212 415

72.3 -67 -90 136.3 73 165 222.0 215 420

73.1 -65 -85 137.8 76 170 223.9 218 425

74.3 -62 -80 139.3 79 175 225.8 221 430

75.5 -59 -75 140.8 82 180 227.7 223 435

76.7 -56 -70 142.3 85 185 229.6 226 440

78.0 -53 -65 143.8 87 190 231.5 229 445

78.8 -51 -60 145.3 90 195 233.5 232 450

80.0 -48 -55 146.8 93 200 235.4 235 455

81.2 -45 -50 148.4 96 205 237.4 237 460

82.2 -42 -45 149.9 98 210 239.3 240 465

82.9 -40 -40 151.5 101 215 241.3 243 470

84.2 -37 -35 153.0 104 220 243.3 246 475

85.7 -34 -30 154.6 107 225 245.3 248 480

86.9 -31 -25 156.2 110 230 247.2 251 485

88.1 -28 -20 157.7 112 235 249.3 254 490

88.9 -26 -15 159.3 115 240 251.2 257 495

90.1 -23 -10 160.9 118 245 253.3 260 500

91.4 -20 -5 162.5 121 250 255.2 262 505

92.2 -17 0 164.2 123 255 257.3 265 510

93.4 -15 5 165.8 126 260 259.3 268 515

94.6 -12 10 167.4 129 265 261.4 271 520

95.8 -9 15 169.0 132 270 263.4 273 525

97.1 -6 20 170.7 135 275 265.5 276 530

98.3 -3 25 172.3 137 280 267.6 279 535

99.5 -1 30 174.0 140 285 269.6 282 540

100.8 1 35 175.7 143 290 271.7 285 545

102.0 4 40 177.4 146 295 273.8 287 550

103.3 7 45 179.1 148 300 275.9 290 555

104.6 10 50 180.8 515 305 278.0 293 560

105.9 12 55 182.5 154 310 280.1 296 565

107.2 15 60 184.2 157 315 282.3 298 570

108.5 18 65 185.9 160 320 284.4 301 575

109.8 21 70 187.6 162 325 286.5 304 580

111.1 23 75 189. 165 330 288.6 307 585

112.5 26 80 191.1 168 335 290.8 310 590

113.8 29 85 192.9 171 340 293.1 312 595

115.2 32 90 194.5 173 345 295.2 315 600

116.5 35 95 196.4 176 350 297.5 318 605

117.9 37 100 198.2 179 355 299.8 321 610

119.2 40 105 199.9 182 360 301.4 323 615

120.6 43 110 201.7 185 365 303.7 326 620

122.0 46 115 203.5 187 370 306.0 329 625

123.4 48 120 205.3 190 375 308.3 332 630

124.8 51 125 207.2 193 380 310.6 335 635

126.2 54 130 109.0 196 385 312.2 337 640

127.6 57 135 210.8 198 390 314.5 340 645

129.0 60 140 212.7 201 395 316.8 343 650

130.5 62 145 214.5 204 400 319.1 346 655

131.9 65 150 216.4 207 405 320.6 348 660

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APPENDIX G—FACTORY DEFAULT CONFIGURATION V3.1X

910 SERIES HTC

BASIC MODE MENU

(All other parameters are set as shown in the Advanced Mode Sub-Menus)

Configuration Mode Menu
Parameter Factory User

Control Setpoint 68°F (20°C)
Lo TS 1 14°F (–10°C)
Lo Load 1.0A
Switch Control Mode Deadband
Circuit Breaker *n/a (30.0A)
Temperature Units °F
Feature Mode Basic

ADVANCED MODE MENUS

Configuration Mode Main Menu
Parameter Factory User

Control Setpoint 68°F (20°C)
Lo TS 1 14°F (–10°C)
Lo Load 1.0 A
Hi GFI 20 mA
GFI Trip 30 mA
Feature Mode Advanced

TS Alarms Configuration Sub-Menu
Parameter Factory User

TS 1 Fail Enable
Lo TS 1 Enable
Lo TS 1 14°F (–10°C)
Hi TS 1 Disable
Hi TS 1 *n/a

(212°F (100°C))
TS 2 Fail Disable
Lo TS 2 Disable
Lo TS 2 *n/a

(14°F (–10°C))
Hi TS 2 Disable
Hi TS 2 *n/a

(212°F (100°C))
Lo TS Filter 0 min
Hi TS Filter *n/a (0 min)
Latch TS Alarms Yes
CTL TS Fail Enable

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Other Alarms Configuration Sub-Menu
Parameter Factory User

Lo Load Enable Lo Load 1.0 A Lo Load Filter 0 sec
Hi Load Disable
Hi Load *n/a (30.0A)
Hi Load Filter *n/a (0 sec)
Hi GFI Enable
Hi GFI 20 mA
Hi GFI Filter 0 sec
GFI Trip Enable
GFI Trip 30 mA
Lo Volt Enable
Lo Volt 90 V
Lo Volt Filter 0 sec
Hi Volt Disable
Hi Volt *n/a (270V)
Hi Volt Filter *n/a (0 sec)
Lo Resist Disable
Lo Resist *n/a (50%)
Lo Resist Filter *n/a (0 sec)
Hi Resist Disable
Hi Resist *n/a (50%)
Hi Resist Filter *n/a (0 sec)

NominalResist *n/a(6.00Ω)

Overcurrent Trip *n/a (Enable)
Switch Fail Enable
HTC Reset Disable
C.B. Limiting *n/a (Disable)
Power Limiting *n/a (Disable)
Switch Limiting *n/a (Disable)
Contactor Count Enable
Contactor Count 200,000
EEROM Data Fail Enable

nVent.com | 75

Point Setup Sub-Menu
Parameter Factory User

Tag TAG -(factory ID)
Switch Control Mode Deadband
Prop Band *n/a (4°F (2°C))
Deadband 5°F (3°C)
Cycle Time *n/a (10 min)
Switch Rating *n/a (30.0 A)
Circuit Breaker *n/a (30.0 A)
Max Power *n/a (7200 W)
TS Fail Mode Off
TS CTL Mode TS1-Fail Off

TS1Type 100ΩPlat
TS1LeadResist *n/a(0)Ω

TS 1 Hi Limit Disable

TS2Type 100ΩPlat
TS2LeadResist *n/a(0Ω)

TS 2 Hi Limit Disable
Autocycle Enable
Autocycle Interval 8
Autocycle Units Hours
Override Source Remote
Load Shedding Disable

Miscellaneous Setup Sub-Menu
Parameter Factory User

Temperature Units °F
Version V3.1x.xx n/a
Ext. Input Not used
Flash Alarm Output Yes
Alarm Output N.C.
Language English
Passcode 0
Scroll Delay 0.15 sec
Load Defaults (See user manual)

Communications Setup Sub-Menu
Parameter Factory User

Protocol HTCBUS
HTCBUS Addr (factory ID)
Modbus Addr *n/a (1)
Modbus Sub Addr *n/a (0)
Baud Rate Auto
Parity *n/a (None)
Hardware None, modem, RS-232, RS-485 n/a
Driver Auto
Profile Auto
Tx Delay 0.06 sec

*n/a: Parameter may only appear if certain features are enabled. Values shown in brackets are the
Factory defaults if the settings are enabled. This information defines the default 910 Series Control
Module configuration as set by the Factory for firmware V3.1X. These settings are subject to change
without notice. It is the user’s responsibility to verify that all configuration parameters are chosen
appropriately for the intended application.

76 | nVent.com

North America

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Raychem-IM-H56873-910series-EN-1805

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