McQuay AWS 150A Installation Manual

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Operating & Maintenance Manual

Group: Chiller

Part Number: 10000199900

Date: Sept 2010

Supercedes: July 2010

OM 1051-2

Pathfinder™ Air-Cooled Chillers

AWS 150A through AWS 530A (Includes Optional Compressor VFD Models)

50/60 Hertz,

R-134a

Software Version: 2507500205

Table of Contents

INTRODUCTION ........................................................3

OPERATING LIMITS: ...............................................4

CONOMIZER CONTROL

IQUID INJECTION

IQUID LINE SOLENOID VALVE

APACITY OVERRIDES – LIMITS OF OPERATION

........................................... 42

.................................................... 42

............................... 43

...... 43

CONTROLLER FEATURES .....................................4

GENERAL DESCRIPTION........................................5

ONTROL PANEL LAYOUT

OWER PANEL LAYOUT

CONOMIZER COMPONENTS

CONTROLLER DESCRIPTION ...............................9

ARDWARE STRUCTURE

YSTEM ARCHITECTURE

SEQUENCE OF OPERATION ................................11

CONTROLLER OPERATION.................................15

ETPOINTS

UNIT FUNCTIONS....................................................22

ALCULATIONS

NIT AVAILABILITY

NIT MODE SELECTION

NIT CONTROL STATES

NIT STATUS

CE MODE START DELAY

VAPORATOR PUMP CONTROL

OISE REDUCTION

EAVING WATER TEMPERATURE

NIT CAPACITY CONTROL

NIT CAPACITY OVERRIDES

CIRCUIT FUNCTIONS ............................................34

................................................................18

.........................................................22

............................................................24

....................................................25

..........................................5

..............................................6

.......................................7

.............................................9

...........................................10

.................................................22

............................................23

..........................................24

.................................25

(LWT) R

........................................28

.....................................30

ESET

.......26

ALARMS AND EVENTS ......................................... 44

IGNALING ALARMS

LEARING ALARMS/FAULTS

ESCRIPTION OF ALARMS

LARM LISTING

NIT FAULTS

NIT WARNINGS

IRCUIT FAULTS

IRCUIT PROBLEMS

LARM LOGGING

VENT LOG

.............................................................. 55

................................................ 44

.................................... 44

........................................ 45

....................................................... 45

........................................................... 47

...................................................... 48

...................................................... 49

................................................. 54

..................................................... 55

USING THE CONTROLLER.................................. 56

AVIGATING

OPTIONAL REMOTE USER INTERFACE ......... 61

............................................................ 57

OPTIONAL COMPRESSOR VFD.......................... 63

AULTS AND MINOR FAULTS/ALARMS

LEARING

AVIGATING

OPTIONAL POWER FACTOR CORRECTION

CAPACITORS........................................................... 67

START-UP AND SHUTDOWN ............................... 68

EMPORARY SHUTDOWN

XTENDED (SEASONAL) SHUTDOWN

FIELD WIRING DIAGRAM ................................... 71

VFD F

AULTS

.......................................... 63

AULT CODES

......................................... 68

.................... 63

............................ 63

....................... 69

ALCULATIONS

IRCUIT CONTROL LOGIC

IRCUIT STATUS

OMPRESSOR CONTROL

ONDENSER FAN CONTROL

AN CONTROL WITHOUT

AN CONTROL WITH

EXV C

ONTROL

.........................................................34

.........................................35

.......................................................36

............................................37

......................................38

VFD ..................................38

VFD.........................................40

.........................................................40

Modbus

Manufactured in an ISO Certified Facility

SYSTEM MAINTENANCE ..................................... 73

REVENTATIVE MAINTENANCE SCHEDULE

APPENDIX ................................................................ 78

EFINITIONS

............................................................ 78

.............. 77

Unit controllers are LONM

optional LONW

ORKS

ARK

certified with an

communications module

2010 McQuay International. Information covers the McQuay International products at the time of publication and we reserve the right to make changes in design and construction at anytime without notice.  The following are trademarks or registered trademarks of their respective companies: BACnet from ASHRAE; LONM from McQuay International; Excel from Microsoft Corp.

2 OM 1051-2

ARK and LONWORKS

from Echelon Corporation; McQuay, MicroTech III, Guardister, and Open Choice

Introduction

This manual provides setup, operating, troubleshooting and maintenance information for the Daiken McQuay Pathfinder chillers.

Dangers indicate a hazardous situation which will result in death or serious injury if not avoided.

Warnings indicate potentially hazardous situations, which can result in property damage, severe

Cautions indicate potentially hazardous situations, which can result in personal injury or equipment

Software Version:

The unit software and BSP (Board Support Package) versions can be viewed using the keypad/display. From the Main Menu, turn the knob to the right until you reach the About Chiller menu and press Enter (the knob). The software version is displayed as "App Version =". Scroll down in this menu (turn knob to the right), the BSP version will also be displayed ("BSP Version=").

AZARD IDENTIFICATION INFORMATION

DANGER

WARNING

personal injury, or death if not avoided.

CAUTION

damage if not avoided.

• App Version 2507500205 for units with or without the optional compressor VFDs

WARNING

Electric shock hazard: can cause personal injury or equipment damage. This equipment must be properly grounded. Connections to, and service of, the MicroTech III control panel must be performed only by personnel who are knowledgeable in the operation of this equipment .

CAUTION

Static sensitive components. A static discharge while handling electronic circuit boards can cause damage to the components. Discharge any static electrical charge by touching the bare metal inside the control panel before performing any service work. Never unplug any cables, circuit board terminal blocks, or power plugs while power is applied to the panel.

NOTICE

This equipment generates, uses, and can radiate radio frequency energy and, if not

installed and used in accordance with this instruction manual, can cause interference to

radio communications. Operation of this equipment in a residential area can cause

harmful interference, in which case the user will be required to correct the interference at

the user’s own expense. McQuay International Corporation disclaims any liability

resulting from any interference or for the correction thereof.

OM 1051-2 3

Operating Limits:

• Maximum standby ambient temperature, 130°F (55°C)

• Maximum operating ambient temperature is 115°F (46°C), or 125°F (52°C) with the addition

of the optional high ambient package

• Minimum operating ambient temperature (standard), 35°F (2°C)

• Minimum operating ambient temperature (with optional low-ambient control), 0°F (-18°C)

• Leaving chilled water temperature, 39.2°F to 59.0°F (4.0°C to 15.0°C)

• Leaving chilled fluid temperatures with glycol, 24.8°F to 59.0°F (-4.0°C to 15.0°C). Normal

unloading.

• Leaving temperature in ICE mode, 17.6°F to 39.2°F (-8.0°C to 4°C). No unloading.

• Operating Delta-T range, 6°F to 16°F (3.3°C to 8.9°C)

• Maximum operating inlet fluid temperature, 76°F (24°C)

• Maximum non-operating inlet fluid temperature, 100°F (38°C)

Controller Features

Readout of the following temperature and pressure readings:

• Entering and leaving chilled water temperature

• Saturated evaporator refrigerant temperature and pressure

• Saturated condenser temperature and pressure

• Outside air temperature

• Suction and discharge line temperatures − calculated superheat for discharge and suction

lines

• Oil pressure

Automatic control of primary and standby chilled water pumps. The control will start one of the pumps (based on lowest run-hours) when the unit is enabled to run (not necessarily running on a call for cooling) and when the water temperature reaches a point of freeze possibility.

Two levels of security protection against unauthorized changing of setpoints and other control parameters.

Warning and fault diagnostics to inform operators of warning and fault conditions in plain language. All events and alarms are time and date-stamped for identification of when the fault condition occurred.

Twenty-five previous alarms are available.

Remote input signals for chilled water reset, demand limiting, and unit enable.

Test mode allows the service technician to manually control the controllers’ outputs and can be useful for system checkout.

Building Automation System (BAS) communication capability via LonTalk, Modbus, or BACnet standard protocols for all BAS manufacturers-simplified with McQuay’s Open Choices feature.

Pressure transducers for direct reading of system pressures. Preemptive control of low evaporator pressure conditions and high discharge temperature and pressure to take corrective action prior to a fault trip.

4 OM 1051-2

General Description

Switch

The control panel is located on the front of the unit at the compressor end. There are three doors. The control panel is behind to left-hand door. The power panel is behind the middle and right-hand doors.

General Description

The MicroTech III control system consists of a microprocessor-based controller and a number of extension modules, which vary depending on the unit size and conformation. The control system provides the monitoring and control functions required for the controlled, efficient operation of the chiller.

The operator can monitor all critical operating conditions by using the screen located on the main controller. In addition to providing all normal operating controls, the MicroTech III control system will take corrective action if the chiller is operating outside of its normal design conditions. If a fault condition develops, the controller will shut a compressor, or the entire unit, down and activate an alarm output.

The system is password protected and only allows access by authorized personnel. Except that some basic information is viewable and alarms can be cleared without a password. No settings can be changed.

Additional information about the Daikin McQuay Pathfinder Chiller is available in Catalog 600 and IM 997, which can be found on www.mcquay.com.

Control Panel Layout

Figure 1, Control Panel Components, Three-Circuit Unit, w/o VFD

Controller

Fuse

Emergency

Switch

Relay

Control

Circuit

Breaker

Unit On/Off

Circuit #1

Pumpdown

Circuit #2

Pumpdown

Switch

Circuit #3

Pumpdown

Switch

Alarm & Limit Extension Module

MicroTech III Main Controller

Fan Control Extension Modules

Emergency Switch Located on Front Door

OM 1051-2 5

NOTES:

Fan

Circuit Breaker

1 per Fan

Circuit #

Circuit Breaker

1. The Emergency Switch Relay de-energizes all circuit’s control power when activated, causing an

immediate compressor and fan shutdown. The red emergency button switch is located on the front of the control panel door.

2. The control power transformer is located in the power panel adjacent to the control panel.

3. Additional extension (aka expansion) modules are located elsewhere on the chiller.

4. See the VFD section for a description of the panel used with the VFD option as it is considerably

different from the standard panel.

Power Panel Layout

The power panel is at the front of the unit, behind the two doors to the right.

Figure 2, Power Panel, Three-Circuit Units, w/o VFD

Fan Contactors

1 per Fan, Circuit #2

Fan Contactors

1 per Fan, Circuit #3

Compressor #1

Circuit Breaker

Single Point

Disconnect Switch with

Compressor #3

Compressor #2

6 OM 1051-2

Line/120V

Transformer

Incoming Power

Connections

NOTE: See the VFD section of this manual for a description of the power used with the VFD option as it is considerably different from the standard panel.

Economizer Components

The chiller may or may not have economizers depending on design capacity requirements. An economizer is a well-proven device to increase a refrigerant circuit’s capacity and efficiency.

Figure 3, Economizer Components

Brazed-plate

Heat Exchanger

Gas to Comp.

Interstage

Liquid from Condenser

TXV LLSV

Warm liquid from the condenser is fed into the economizer where it is cooled by flashing off liquid also from the condenser. The flash gas is piped to a compressor interstage point. Lowering the liquid refrigerant temperature to the evaporator decreases its enthalpy (heat content) and results in a greater amount of heat absorption from the chilled water.

OM 1051-2 7

Liquid Feed to Economizer

Liquid Feed to Evaporator

Figure 4, Piping Schematic with Economizer Circuit, One Circuit Shown

Figure 5, Piping Schematic without Economizer Circuit, One Circuit Shown

8 OM 1051-2

Controller Description

Hardware Structure

The MicroTech III control system for Pathfinder chillers consists of a main unit controller with a number of extension input/output I/O modules attached depending on the chiller size and configuration.

One of the optional BAS communication modules may be included.

An optional Remote Operator Interface panel may be included, connected with up to nine Pathfinder units.

The MicroTech III controllers used on Pathfinder chillers are not interchangeable with previous MicroTech II controllers.

MicroTech III unit controller

Remote Operator Interface

BACnet/

MSTP

Communication

MODbus LON

BACnet/IP

Extension I/O Modules

OM 1051-2 9

System Architecture

The overall controls architecture uses the following:

• One MicroTech III main controller

• I/O extension modules (sometimes referred to as “controllers”) as needed depending

on the configuration of the unit

• Optional BAS interface as selected

Figure 6, System Architecture

BAS Interface (BACnet, Lon,

Modbus)

MicroTech III Main Controller

Peripheral Bus

I/O Extension

Alarm/Limiting

I/O Extension

Compressor 1

I/O Extension

Compressor 2

I/O Extension

Compressor 3

I/O Extension

Fans Circuit 1

and 2

I/O Extension

EXV 1

I/O Extension

EXV 2

I/O Extension

EXV 3

I/O Extension Fans Circuit 3

I/O Extension

Fans Circuit 3

and 4

I/O Extension Fans Circuit 4

I/O Extension

Compressor 4

I/O Extension

EXV 4

10 OM 1051-2

Sequence of Operation

Figure 7, Unit Sequence of Operation (see Figure 9 for circuit sequence of operation)

Unit power up

Unit in Off state

Is unit enabled?

Yes

Is low ambient lockout

active?

Evaporator pump output on

AWS Chiller Sequence of Operation in Cool Mode

The chiller may be disabled via the unit switch, the remote switch, the keypad enable setting, or the BAS network. In addition, the chiller will be disabled if all

circuits are disabled, or if there is a unit alarm. If the chiller is disabled, the unit status display will reflect this and also show why it is disabled.

If the unit switch is off, the unit status will be Off:Unit Switch. If the chiller is disabled due to network command, the unit status will be Off:BAS Disable. When

Yes

the remote switch is open, the unit status will be Off:Remote Switch. When a unit alarm is active, the unit status will be Off:Unit Alarm. In cases where no circuits are enabled, the unit status will be Off:All Cir Disabled. If the unit is disabled via the Chiller Enable set point, the unit status will be Off:Keypad Disable.

Low ambient lockout will prevent the chiller from starting even if it is otherwise enabled. When this lockout is active, the unit status will be Off:Low OAT Lock.

If the chiller is enabled, then the unit will be in the Auto state and the evaporator water pump output will be activated.

Is flow present?

Yes

Wait for chilled water loop to

recirculate.

Keep pump output on while chiller is enabled and either

running or ready to run.

Is there enough load to

start chiller?

Yes

The chiller will then wait for the flow switch to close, during which time the unit status will be Auto:Wait for flow.

After establishing flow, the chiller will wait some time to allow the chilled water loop to recirculate for an accurate reading of the leaving water temperature. The unit status during this time is Auto:Evap Recirc.

The chiller is now ready to start if enough load is present. If the LWT is not higher than the Active Setpoint plus the Start Up Delta T, the unit status will be Auto:Wait for load.

If the LWT is higher than the Active Setpoint plus the Start Up Delta T, the unit status will be Auto. A circuit can start at this time.

OM 1051-2 11

12 OM 1051-2

OM 1051-2 13

Figure 8, Circuit Sequence of Operation

Unit power up

Circuit is in Off state

Is circuit is enabled to

start?

Yes

Are compressor cycle

timers active?

Is compressor oil sump

ready?

AWS Sequence of Operation - Circuits

When the circuit is in the Off state the EXV is closed, compressor is off, and all fans are off.

The circuit must be enabled before it can run. It may be disabled for several reasons. When the circuit switch is off, the status will be Off:Circuit Switch. If the BAS has disabled the circuit, the status will be Off:BAS Disable. If the circuit

Yes

has an active stop alarm then the status will be Off:Cir Alarm. If the circuit has been disabled via the circuit mode set point, the status will be Off:Cir Mode Disable.

A minimum time must pass between the previous start and stop of a compressor and the next start. If this time has not passed, a cycle timer will be active and the circuit status will be Off:Cycle Timer.

If the compressor is not ready due to refrigerant in the oil, the circuit cannot start. The circuit status will be Off:Refr In Oil.

Yes

Circuit is ready to start

Is circuit commanded to

start?

Yes

Run circuit

Is circuit commanded to

shut down?

Yes

Pumpdown circuit

If the compressor is ready to start when needed, the circuit status will be Off:Ready.

When the circuit begins to run, the compressor will be started and the EXV, fans, and other devices will be controlled as needed. The normal circuit status at this time will be Run.

When the circuit is commanded to shut down, a normal shut down of the circuit will be performed. The circuit status during this time will be Run:Pumpdown. After the shut down is completed, the circuit status will normally be Off:Cycle Timer initially.

14 OM 1051-2

Controller Operation

MicroTech III Inputs/Outputs

I/O for the unit control and for circuits one and two are found on CP1. The chiller may be equipped with two or three compressors.

Analog Inputs

# Description Signal Source Expected Range

AI1 Evaporator Entering Water Temp NTC Thermister (10K@25°C) -50°C – 120°C

AI2 Evaporator Leaving Water Temp NTC Thermister (10K@25°C) -50°C – 120°C

AI3 Evaporator #1 Leaving Water Temp (*) NTC Thermister (10K@25°C) -50°C – 120°C

X1 Evaporator #2 Leaving Water Temp (*) NTC Thermister (10K@25°C) -50°C – 120°C

X2 Outside Ambient Temperature NTC Thermister (10K@25°C) -50°C – 120°C

X4 LWT Reset 4-20 mA Current 1 to 23 mA

*Evaporator #1 LWT and Evaporator #2 LWT will only be used when unit is configured with four circuits

Analog Outputs

# Description Output Signal Range

X5 Fan VFD #1 0-10VDC 0 to 100% (1000 steps resolution)

X6 Fan VFD #2 0-10VDC 0 to 100% (1000 steps resolution)

X7 Fan VFD #3 0-10VDC 0 to 100% (1000 steps resolution)

X8 Fan VFD #4 0-10VDC 0 to 100% (1000 steps resolution)

Digital Inputs

# Description Signal Off Signal On

DI1 Unit PVM Fault No Fault

DI2 Evaporator Flow Switch No Flow Flow

DI3 Double Setpoint/ Mode Switch Cool mode Ice mode

DI4 Remote Switch Remote off Remote on

DI5 Unit Switch Unit off Unit on

DI6 Emergency Stop Unit off/rapid stop Unit on

Digital Outputs

# Description Output OFF Output ON

DO1 Evaporator Water Pump Pump Off Pump On

Alarm Active

DO2 Unit Alarm Alarm not Active

DO3 Circuit #1 Fan Step #1 Fan Off Fan On

DO4 Circuit #1 Fan Step #2 Fan Off Fan On

DO5 Circuit #1 Fan Step #3 Fan Off Fan On

DO6 Circuit #1 Fan Step #4 Fan Off Fan On

DO7 Circuit #2 Fan Step #1 Fan Off Fan On

DO8 Circuit #2 Fan Step #2 Fan Off Fan On

DO9 Circuit #2 Fan Step #3 Fan Off Fan On

DO10 Circuit #2 Fan Step #4 Fan Off Fan On

(Flashing= circuit

alarm)

OM 1051-2 15

Expansion I/O Compressor #1 to #3

Analog Inputs

# Description Signal Source Expected Range

X1 Discharge Temperature NTC Thermister (10K@25°C) -50°C – 125°C X2 Evaporator Pressure Ratiometric 0.5-4.5 Vdc -100 kPa to 700 kPa X3 Oil Pressure Ratiometric 0.5-4.5 Vdc 0 kPa to 3000 kPa X4 Condenser Pressure Ratiometric 0.5-4.5 Vdc 0 kPa to 3000 kPa X7 Motor Temperature See note below

Note: European chillers will have the PTC thermistor in the compressor motor connected to this input. X7 is configured as an NTC 10k input for European chillers.

Analog Outputs

# Description Output Signal Range

Not Needed

Digital Inputs

# Description Signal Off Signal On

X6 Starter Fault Fault No fault X7 Motor Protection See note below DI1 High Pressure Switch Fault No fault

Note: US chillers will use the motor protection board connected to this input. X7 is configured as a digital input for US chillers.

Digital Outputs

Europe Configuration

# Description Output Off Output On

DO1 Start Compressor Compressor Off Compressor On DO2 Economizer Solenoid Closed Solenoid Open DO3 Non-modulating Slide Load/Unload Solenoid Closed Solenoid Open DO4 Liquid Injection Solenoid Closed Solenoid Open DO5 Modulating Slide Load Solenoid Closed Solenoid Open DO6 Modulating Slide Unload Solenoid Closed Solenoid Open

X5 Modulating Slide “turbo” Solenoid Closed Solenoid Open

U.S. Configuration

# Description Output Off Output On

DO1 Start Compressor Compressor Off Compressor On

DO2 Economizer Solenoid Closed Solenoid Open

DO3 Non-modulating Slide Load Solenoid Closed Solenoid Open

DO4 Non-modulating Slide Unload Solenoid Closed Solenoid Open

DO5 Modulating Slide Load Solenoid Closed Solenoid Open

DO6 Modulating Slide Unload Solenoid Closed Solenoid Open

X5 Modulating Slide ‘Turbo’ Solenoid Closed Solenoid Open

X8 Liquid Injection Solenoid Closed Solenoid Open

16 OM 1051-2

I/O EXV Circuit #1 to #3

Analog Inputs

# Description Signal Source Expected Range

X2 Suction Temperature NTC Thermister 10K@25°C) -50°C – 120°C X3 Slide Position LVDT 4 to 20 mA 0% to 100%

Analog Outputs

# Description Output Signal Range

Not Needed

Digital Inputs

# Description Signal Off Signal On

DI1 Low Pressure switch Fault No fault

Digital Outputs

# Description Output Off Output On

DO1 Liquid Line Solenoid Closed Solenoid Open

Stepper Motor Output

# Description

M1+

M1-

M2+

M2-

EXV Stepper Coil 1

EXV Stepper Coil 2

Extension I/O Fan Module Circuit #1 & 2

Digital Inputs

# Description Output Off Output On

DI1 PVM/GFP Circuit #1 Fault No fault

DI2 PVM/GFP Circuit #2 Fault No fault

Digital Outputs

# Description Output Off Output On

DO1 Circuit #1 Fan Step #5 Fan Off Fan On

DO2 Circuit #1 Fan Step #6 Fan Off Fan On

DO3 Circuit #2 Fan Step #5 Fan Off Fan On

DO4 Circuit #2 Fan Step #6 Fan Off Fan On

Extension I/O Fan Module Circuit #3

Digital Outputs

# Description Output Off Output On

DO1 Circuit #3 Fan Step #5 Fan Off Fan On

DO2 Circuit #3 Fan Step #6 Fan Off Fan On

Extension I/O Unit Alarm & Limiting

Analog Inputs

# Description Signal Source Range

X3 Demand Limit 4-20 mA 1 to 23 mA

X4 Unit Current 4-20 mA 1 to 23 mA

Analog Outputs

# Description Output Signal Range

Not Needed

OM 1051-2 17

Digital Inputs

# Description Signal Off Signal On

X1 External Alarm/Event

X2 Current Limit Enable No Limiting Limiting

X5 Circuit Switch #1 Circuit Off Circuit On

X6 Circuit Switch #2 Circuit Off Circuit On

X7 Circuit Switch #3 Circuit Off Circuit On

External Device Failure

External Device OK

Digital Outputs

# Description Output Off Output On

DO1 Evaporator Water Pump #2 Pump Off Pump On

DO2 Open

DO3 Circuit #1 Alarm No Alarm Alarm

DO4 Circuit #2 Alarm No Alarm Alarm

DO5 Circuit #3 Alarm No Alarm Alarm

Setpoints

The following parameters are remembered during power off, are factory set to the Default value, and can be adjusted to any value in the Range column.

Read and write access to these setpoint is determined by the Global HMI (Human Machine Interface) Standard Specification.

Table 1, Setpoint Default and Range

Description Default Range

Unit

Manufacturing Location

Frequency

Voltage

Unit Enable

Unit Status after Power Failure

Not Selected

60 Hz

460 V

Enable

Not Selected, Europe, USA

50, 60

230, 380, 400, 460, 575

Disable, Enable

Enable Disable, Enable

Control source Local Local, Network

Available Modes Cool

Cool LWT 1 Cool LWT 2 Cool LWT 1 with Glycol Cool LWT 2 with Glycol Ice LWT

7.0°C (44.6°F)

-4.0°C (24.8°F)

4.0°C to 15.0°C (39.2°F to 59.0°F)

-4.0°C to 15.0°C (24.8°F to 59.0°F)

Cool, Cool w/Glycol

Cool/Ice w/Glycol, Ice, Test

-8.0°C to 4.0°C (17.6°F to 39.2°F)

Startup Delta T 2.7 deg C (4.9 deg F) 0 to 5.0 deg C (0 to 9.0 deg F) Shut Down Delta T 1.5 deg C (2.7 deg F) 0 to 1.7 deg C (0 to 3.1 deg F) Stage Up Delta T 0.5 deg C (0.9 deg F) 0 to 1.7 deg C (0 to 3.1 deg F) Stage Down Delta T 0.7 deg C (1.3 deg F) 0 to 1.7 deg C (0 to 3.1 deg F)

Max Pulldown

1.7 deg C/min

(3.1 deg F/min)

0.3 to 2.7 deg C/min

(0.5 to 4.9 deg F/min)

Continued next page.

Description Default Range

Nominal Evap Delta T 2 Cir 5.6 deg C (10.1 deg F) 3.3 to 8.9 deg C (5.9 to 16.0 deg F) Nominal Evap Delta T 3 Cir 5.6 deg C (10.1 deg F) 3.3 to 10 deg C (5.9 to 18.0 deg F) Variable Evap Flow No No, Yes

18 OM 1051-2

Evap Recirc Timer 30 sec 0 to 300 seconds

Pump Control #1 Only

#1 Only, #2 Only, Auto,

#1 Primary, #2 Primary LWT Reset Type None None, 4-20mA, OAT Max Reset 5.0 deg C (9.0 deg F) 0 to 10.0 deg C (0 to 18.0 deg F) Start Reset Delta T 5.0 deg C (9.0 deg F) 0 to 10.0 deg C (0 to 18.0 deg F) Max Reset OAT Start Reset OAT

15.5°C (59.9°F)

23.8°C (74.8°F)

10.0°C to 30.0°C (50°F to 86.0 °F)

Soft Load Off Off, On Begin Capacity Limit 40% 20-100% Soft Load Ramp 20 min 1-60 minutes Demand Limit Off Off, On Current @ 20mA 800 A 0 to 2000 A Current limit Setpoint 800 A 0 to 2000 A # of Circuits 2 2, 3 Ice Delay Timer 12 hrs 1-23 hours Clear Ice Timer No No, Yes PVM Multi Point Single Point, Multi Point , None(SSS) Noise Reduction Disabled Disabled, Enabled Noise Reduction Start Time 21:00 18:00 – 23:59 Noise Reduction End Time 6:00 5:00 – 9:59 Noise Reduction Offset 5.0 deg C (9.0 deg F) 0 to 14.0 deg C (0 to 25.2 deg F) Evap LWT Sensor Offset 0 deg C (0 deg F) -5.0 to 5.0 deg C (-9.0 to 9.0 deg F) Evap EWT Sensor Offset 0 deg C (0 deg F) -5.0 to 5.0 deg C (-9.0 to 9.0 deg F) OAT Sensor Offset 0 deg C (0 deg F) -5.0 to 5.0 deg C (-9.0 to 9.0 deg F)

Compressors-Global

Start-start timer 20 min 15-60 minutes Stop-start timer 5 min 3-20 minutes Pumpdown Pressure 100 kPa (14.5 psi) 70 to 280 kPa (10.2 to 40.6 psi) Pumpdown Time Limit 120 sec 0 to 180 sec Light Load Stage Down 40% 26 to 50% High Load Stage Up 80% 50 to 100% Stage Up Time 5 min 0 to 60 min Stage Down Time 3 min 3 to 30 min Stage Delay Clear No No, Yes Soft Load Off Off, On Max # Comps Running 2 2,3 Sequence # Cir 1 1 1-3 Sequence # Cir 2 1 1-3 Sequence # Cir 3 1 1-3 Liquid Injection Activation

85.0°C (185.0°F)

50.0°C to 110.0°C (122.0°C to 230.0°F)

Liq. Line Solenoid Valves No No, Yes Slide Position Sensors Yes No, Yes

Continued next page.

OM 1051-2 19

Description Default Range

Alarm Limits

Low Pressure-Unload 160 kPa (23 psi) 160 kPa to 310 kPa (23 psi to 48 psi) Low Pressure-Hold 180 kPa (26 psi) 180 kPa to 310 kPa (26 psi to 48 psi) Low Press-Unload w/ Glycol 160 kPa (23 psi) 0 kPa to 310 kPa (0 psi to 48 psi) Low Press-Hold w/Glycol 180 kPa (26 psi) 0 kPa to 310 kPa (0 psi to 48 psi) High Oil Press Diff Delay 30 sec 10-180 sec High Oil Press Differential 250 kPa (36 psi) 0 to 415 kPa (0 to 60 psi) High Discharge Temperature 110.0°C (230.0°F) 65.0 to 110.0 °C (149.0 to 230.0°F) High Cond Pressure Delay 5 sec 0 to 30 sec Low Pressure Ratio Delay 90 sec 0 to 180 sec Start Time Limit 60 sec 20 to 180 sec Evap. Water Freeze Evap. Water Freeze w/ Glycol

2.2°C (36.0°F)

1.1°C to 6.0°C (34.0°F to 42.8°F)

-18.0°C to 6.0°C (-0.4°F to 42.8°F)

Evaporator Flow Proof 15 sec 5 to 15 sec Recirculate Timeout 3 min 1 to 10 min Low OAT Lockout Low OAT Lockout/with Fan VFD

12.0°C (53.6°F)

2.0°C to 15.0°C (35.6°F to 59.0°F)

-23.0°C to 15.0°C (-9.4°F to 59.0°F)

The following setpoints exist individually for each circuit:

Description

Default Range

Circuit mode Enable Disable, enable, test

Compressor Size for Non-VFD HSA204

Compressor Size for VFD HSV204

HSA192, HSA204, HSA215 HSA232, HSA241, HSA263

HSV204, HSV215

HSV232, HSV241, HSV263 Economizer (VFD Only) With With, Without Capacity Control Auto Auto, Manual Manual Capacity See Note 1 0 to 100% Clear Cycle Timers No No, Yes EXV control Auto Auto, manual Service Pumpdown No No, Yes Economizer Enable Capacity (VFD Model Only)

40% 40 to 75%

Evap pressure Sensor offset 0 kPa (0 psi) -100 to 100 kPa (-14.5 to 14.5 psi) Cond pressure Sensor offset 0 kPa (0 psi) -100 to 100 kPa (-14.5 to 14.5 psi) Oil pressure Sensor Offset 0 kPa (0 psi) -100 to 100 kPa (-14.5 to 14.5 psi) Suction temp Sensor Offset 0 deg C (0 deg F) -5.0 to 5.0 deg C (-9.0 to 9.0 deg F) Discharge temp offset 0 deg C (0 deg F) -5.0 to 5.0 deg C (-9.0 to 9.0 deg F) Slide sensor mA @ minimum

Slide sensor mA @ maximum

4 mA 4 to 22 mA

20 mA 4 to 22 mA

Fans

Fan VFD enable Enable Disable, Enable Number of fans 5 5 to 12 Saturated Condenser Temp Target Min Saturated Condenser Temp Target Max

32.0°C (89.6°F)

43.0°C (109.4°F)

20.0°C to 50.0°C (68.0°F to

122.0°F)

32.0°C to 50.0°C (89.6°F to

122.0°F)

Continued next page.

20 OM 1051-2

Description Default Range

Fan Stage 0 Up Deadband 2.5 deg C (4.5 deg F) 1.0 to 10.0 deg C (1.8 to 18 deg F) Fan Stage 1 Up Deadband 2.5 deg C (4.5 deg F) 1.0 to 10.0 deg C (1.8 to 18 deg F) Fan Stage 2 Up Deadband 4.0 deg C (7.2 deg F) 1.0 to 10.0 deg C (1.8 to 18 deg F) Fan Stage 3 Up Deadband 5.0 deg C (9.0 deg F) 1.0 to 10.0 deg C (1.8 to 18 deg F) Fan Stage 4 Up Deadband 4.0 deg C (7.2 deg F) 1.0 to 10.0 deg C (1.8 to 18 deg F) Fan Stage 5 to 12 Up Deadband

4.0 deg C (7.2 deg F) 1.0 to 10.0 deg C (1.8 to 18 deg F)

Fan Stage 1 Down Deadband 10.0 deg C (18.0 deg F) 1.0 to 10.0 deg C (1.8 to 18 deg F) Fan Stage 2 Down Deadband 4.0 deg C (7.2 deg F) 1.0 to 10.0 deg C (1.8 to 18 deg F) Fan Stage 3 Down Deadband 3.5 deg C (6.3 deg F) 1.0 to 10.0 deg C (1.8 to 18 deg F) Fan Stage 4 Down Deadband 3.0 deg C (5.4 deg F) 1.0 to 10.0 deg C (1.8 to 18 deg F) Fan Stage 5 Down Deadband 2.5 deg C (4.5 deg F) 1.0 to 10.0 deg C (1.8 to 18 deg F) Fan Stage 6 to 12 Down Deadband

2.5 deg C (4.5 deg F) 1.0 to 10.0 deg C (1.8 to 18 deg F)

Fan VFD Max Speed 100% 90 to 110% Fan VFD Min Speed 25% 20 to 60%

Dynamic Default Values

The fan staging dead bands have different default values based on the VFD enable setpoint. When the VFD enable setpoint is changed, a set of default values for the fan staging dead bands is loaded as follows:

Fan VFD is Enabled

Setpoint

Default

loaded (oF)

Stage 0 On Deadband 4.5 Stage 0 On Deadband 7.2

Stage 1 On Deadband 4.5 Stage 1 On Deadband 9.0

Stage 2 On Deadband 7.2 Stage 2 On Deadband 9.9

Stage 3 On Deadband 9.0 Stage 3 On Deadband 10.8

Stage 4 On Deadband 7.2 Stage 4 On Deadband 11.7

Stage 5 On Deadband 7.2 Stage 5 On Deadband 11.7

Stage 2 Off Deadband 7.2 Stage 2 Off Deadband 18

Stage 3 Off Deadband 6.3 Stage 3 Off Deadband 14.4

Stage 4 Off Deadband 5.4 Stage 4 Off Deadband 9.9

Stage 5 Off Deadband 4.5 Stage 5 Off Deadband 7.2

Stage 6 Off Deadband 4.5 Stage 6 Off Deadband 7.2

The low pressure settings have different default values based on the Manufacturing Location setpoint. When the manufacturing location is configured, the default values for these setting are loaded as shown below:

US Chiller

Setpoint Default loaded

Low Evap Press.Unload 160 kPa (23.2 psi) Low Evap Press. Unload 160 kPa (23.2 psi)

Low Evap Press.-Hold 180 kPa (26.1 psi) Low Evap Pressure-Hold 180 kPa (26.1 psi)

Fan VFD is Disabled

Setpoint

Default

loaded (oF)

European Chiller

Setpoint Default loaded

OM 1051-2 21

Unit Functions

Calculations

EWT Slope

EWT slope is calculated such that the slope represents the change in EWT over a time frame of one minute.

Pulldown Rate

The slope value calculated above will be a negative value as the water temperature is dropping. A pulldown rate is calculated by inverting the slope value and limiting to a minimum value of 0°C/min.

Unit Availability

The unit is available to start if the following conditions are true:

1. Unit switch is closed

2. If unit mode is ice and the ice timer has timed out.

3. No unit alarms exist

4. Emergency stop input is closed

5. At least one circuit is enabled

6. Unit enable setpoint is Enable

7. If remote control is connected and remote unit switch is closed

8. If Control Source = Network, BAS Enable = True

Enabling and disabling the chiller is accomplished using setpoints and inputs to the chiller. The unit switch, remote switch input, and Unit Enable Setpoint all are required to be on for the unit to be enabled when the control source is set to local. The same is true if the control source is set to network, with the additional requirement that the BAS request must be on.

Unit is enabled according to the following table. NOTE: An x indicates that the value is ignored.

Table 2, Enable Combinations

Unit

Switch

Off x x x x Off

x x Off x x Off x x x Off x Off

On Local On On x On

x Network x x Off Off

On Network On On On On

Control

Source

Setpoint

Remote

Switch Input

Unit Enable

Setpoint

BAS

Request

Unit

Enable

All of the methods for disabling the chiller, discussed in this section, will cause a normal shutdown (pumpdown) of any running circuits.

When the controller is powered up, the Unit Enable Setpoint will be initialized to ‘Disable’ if the Unit Enable Init Setpoint is set to ‘Disable’. .

22 OM 1051-2

Unit Mode Selection

The operating mode of the unit is determined by setpoints and inputs to the chiller. The Available Modes Setpoint determines what modes of operation can be used. This setpoint also determines whether the unit is configured for glycol use. The Control Source Setpoint determines where a command to change modes will come from. A digital input switches between cool mode and ice mode if they are available and the control source is set to local. The BAS mode request switches between cool mode and ice mode if they are both available and the control source is set to network. The Available Modes Setpoint must only be changed when the unit switch is off. This is to avoid changing modes of operation inadvertently while the chiller is running.

Unit Mode is set according to the following table.

Table 3, Mode Combinations

Control Source

Setpoint

x x x Cool Cool

x x x Cool w/Glycol Cool Local Off x Cool/Ice w/Glycol Cool Local On x Cool/Ice w/Glycol Ice

Network x Cool Cool/Ice w/Glycol Cool Network x Ice Cool/Ice w/Glycol Ice

x x x Ice w/Glycol Ice

x x x Test Test

Notes

1. “x” Indicates that the value is ignored.

2. If the Available Modes Setpoint is set to an option ‘w/Glycol’, then glycol operation should be enabled for the unit. Glycol operation should only be disabled when the Available Modes Setpoint is set to ‘Cool’.

Mode

Input

BAS

Request

Available Modes

Setpoint

Unit Mode

Glycol Configuration

If the Available Modes Setpoint is set to an option w/Glycol, then glycol operation is enabled for the unit. Glycol operation must be disabled only when the Available Modes Setpoint is set to Cool.

Unit Control States

The unit will always be in one of three states:

• Off – Unit is not enabled to run.

• Auto – Unit is enabled to run.

• Pumpdown – Unit is doing a normal shutdown.

Off. The unit should be in the Off state if any of the following are true:

• A unit alarm is active

• All circuits are unavailable to start (cannot start even after cycle timers have expired)

• The unit mode is ice, all circuits are off, and the ice mode delay is active

• Manufacturing Location is not set

• Either manufacturing location or number of circuits have been changed and controller

has not been rebooted

Auto. The unit should be in the Auto state if all of the following are true:

• Manufacturing location is set and controller has been rebooted

• Unit enabled based on settings and switches

• If unit mode is ice, the ice timer has expired

• No unit alarms are active

• At least one circuit is enabled and available to start

OM 1051-2 23

Pumpdown. The unit should be in Pumpdown until all running compressors finish pumping down if any of the following are true:

• Unit is disabled via settings and/or inputs in section Unit Availability.

• Unit pumpdown alarm is triggered

Unit Status

The displayed unit status is determined by the conditions in the following table:

Table 4, Unit Status

Enum

0 Auto Unit State = Auto

1 Off: Ice Mode Tmr

2 Off: OAT Lockout Unit State = Off and Low OAT Lockout is active 3 Off: All Cir Disabled Unit State = Off and all compressors unavailable 4 Off: Unit Alarm Unit State = Off and Unit Alarm active 5 Off: Keypad Disable Unit State = Off and Unit Enable Setpoint = Disable 6 Off: Remote Sw Unit State = Off and Remote Switch is open

7 Off: BAS Disable

8 Off: Unit Sw Unit State = Off and Unit Switch = Disable 9 Off: Test Mode Unit State = Off and Unit Mode = Test

10 Auto: Noise Reduction Unit State = Auto and Noise Reduction is active

11 Auto: Wait for Load

12 Auto: Evap Recirc Unit State = Auto and Evaporator State = Start

13 Auto: Wait for flow

14 Auto: Pumpdn Unit State = Pumpdown

15 Auto: Max Pulldn

16 Auto: Unit Cap Limit

17 Auto: Current Limit

18 Off. Cfg Chg, Rst Ctlr

19 Off Mfg Loc Not Set Mfg Location is not set

Status Conditions

Unit State = Off, Unit Mode = Ice, and Ice Delay = Active

Unit State = Off, Control Source = Network, and BAS Enable = false

Unit State = Auto, no circuits running, and LWT is less than the active setpoint + startup delta

Unit State = Auto, Evaporator State = Start, and Flow Switch is open

Unit State = Auto, max pulldown rate has been met or exceeded

Unit State = Auto, unit capacity limit has been met or exceeded Unit State = Auto, unit current limit has been met or exceeded Unit configuration setpoint has changed, and reboot of controller is required

Ice Mode Start Delay

Compressor Staging in Ice Mode

The first compressor will start when evaporator LWT is higher than the target plus the Startup Delta T setpoint.

When at least one compressor is running, the other compressors will start only when evaporator LWT is higher than the target plus the Stage Up Delta T setpoint.

All compressors will be staged off when evaporator LWT is less than the target.

Stage Up Delay

A fixed stage up delay of one minute between compressor starts is used in this mode. When at least one compressor is running, the other compressors will start as quickly as possible with respect to the stage up delay. An adjustable start-to-start ice delay timer will limit the frequency with which the chiller may start in Ice mode. The timer starts when the first compressor starts while the unit is in ice mode. While this timer is active, the chiller cannot restart in Ice mode. The time delay is user adjustable.

24 OM 1051-2

The ice delay timer may be manually cleared to force a restart in ice mode. A setpoint specifically for clearing the ice mode delay is available. In addition, cycling the power to the controller will clear the ice delay timer.

Evaporator Pump Control

State

Three evaporator pump control states for control of the evaporator pumps:

• Off - No pump on.

• Start – Pump is on, water loop is being recirculated. Recirc timer runnning

• Run – Pump is on, water loop has been recirculated. Recirc timer has timed out

Off The control state is Off when all of the following are true:

• Unit state is Off

• LWT is higher than the Evap Freeze setpoint or LWT sensor fault is active

• EWT is higher than the Evap Freeze setpoint or EWT sensor fault is active

Start. The control state is Start when any of the following are true:

• The unit state is auto

• LWT is less than the Evap Freeze setpoint and LWT sensor fault isn’t active

• EWT is less than the Evap Freeze setpoint and EWT sensor fault isn’t active

Run. The control state is Run when

• The flow switch input has been closed for a time greater than the Evaporator

Recirculate setpoint.

• The flow switch fault is not active

Pump Selection

The pump output used is determined by the Evap Pump Control setpoint. This setting allows the following configurations:

• #1 only – Pump 1 will always be used

• #2 only – Pump 2 will always be used

• Auto – The primary pump is the one with the least run hours, the other is used as

a backup

• #1 Primary – Pump 1 is used normally, with pump 2 as a backup

• #2 Primary – Pump 2 is used normally, with pump 1 as a backup

Primary/Standby Pump Staging

The standby pump will be on if either of the following are true:

• Pump state is Run and the flow switch is open for Evap Proof Time/2

• Pump start is start and Recirculate timeout has expired.

Auto Control

If auto pump control is selected, the primary/standby logic above is still used. When the evaporator is not in the run state, the run hours of the pumps will be compared. The pump with the least hours will be designated as the primary at this time.

Noise Reduction

Noise Reduction is an operating mode designed to reduce unit sound levels by decreasing compressor and fan operating time. It is used during the night when the cooling load is usually reduced and the ambient temperature is lower.

Noise Reduction always requires the Noise Reduction setpoint to be set to ‘enable’. If it is set to ‘disable’, it will not activate for any reason.

Assuming this functionality is enabled, there are two ways it can become active:

OM 1051-2 25

• If the unit mode is cool, and the unit controller clock time is between the Noise

Reduction start time and end time

• Control Source setpoint is set to network, and the BAS command is ‘enable’

When Noise Reduction is active, the Maximum Reset is applied to the cool LWT setpoint. However, if any reset type is selected, that reset will continue to be used rather than the Maximum Reset. Also, the saturated condenser target for each circuit will be offset by the Noise Reduction Condenser Target Offset.

Leaving Water Temperature (LWT) Reset

LWT Target

The LWT Target varies based on settings and inputs and is selected as follows:

Table 5, Leaving Water Temperature Targets

Control Source

Setpoint

Local

Network X X

Local

Network X X

Local

Network

Local x x Ice Setpoint

Network x x

Mode

Input

OFF X Cool Setpoint 1

ON X Cool Setpoint 2

OFF X Cool Setpoint 1

ON X Cool Setpoint 2

OFF x Cool Setpoint 1

ON x Ice Setpoint

x COOL BAS Cool Setpoint x ICE

BAS

Request

Available Modes

Setpoint

COOL

COOL w/Glycol

COOL/ICE w/Glycol

ICE w/Glycol

Base LWT Target

BAS Cool Setpoint

BAS Ice Setpoint

Leaving Water Temperature (LWT) Reset

The base LWT target may be reset if the unit is in Cool mode and it is configured for a reset. The type of reset to be used is determined by the LWT Reset Type setpoint.

When the active reset increases, the Active LWT Target is changed at a rate of

0.2 degrees F every 10 seconds. When the active reset decreases, the Active LWT Target is changed all at once.

After resets are applied, the LWT target can never exceed a value of 60°F.

Reset Type – None

The Active Leaving Water variable is set equal to the current LWT setpoint.

Reset Type – Return Chilled Water

The Active Leaving Water variable is adjusted by the return water temperature.

Return Reset

LWT set Point+Max Reset

Active

LWT

(oF)

(54)

Max Reset

(10)

LWT Set Point

(44)

Evap Delta T (oF)

Start Reset Delta T

26 OM 1051-2

The active setpoint is reset using the following parameters:

1. Cool LWT setpoint

2. Max Reset setpoint

3. Start Reset Delta T setpoint

4. Evap Delta T

Reset varies from 0 to Max Reset setpoint as the Evaporator EWT – LWT (Evap delta t) varies from the Start Reset Delta T set-point to 0.

4-20 mA External Signal Reset

The Active Leaving Water variable is adjusted by the 4 to 20 mA reset analog input. Parameters used:

1. Cool LWT setpoint

2. Max Reset setpoint

3. LWT Reset signal

Reset is 0 if the reset signal is less than or equal to 4 mA. Reset is equal to the Max Reset Delta T setpoint if the reset signal equals or exceeds 20 mA. The amount of reset will vary linearly between these extremes if the reset signal is between 4 mA and 20 mA. An example of the operation of 4-20 reset in Cool mode follows.

4-20 mA Reset - Cool Mode

(54)

Active

LWT

(oF)

Max Reset

(10)

Cool LWT Set

Point (44)

Reset Signal (mA)

Outside Air Temperature (OAT) Reset

The Active Leaving Water variable is reset based on the outdoor ambient temperature. Parameters used:

1. Cool LWT setpoint

2. Max Reset setpoint

3. Start Reset OAT setpoint

4. Max Reset OAT setpoint

5. OAT

Reset is 0 if the outdoor ambient temperature is greater than Start Reset OAT setpoint. From Start Reset OAT setpoint down to Max Reset OAT the reset varies linearly from no reset to the max reset at Max Reset OAT setpoint. At ambient temperatures less than Max Reset OAT setpoint, reset is equal to the Max Reset setpoint.

OM 1051-2 27

Cool LWT+Max Reset

(54)

OAT Reset

Active

LWT

(oF)

Max Reset

(10)

Cool LWT Set-Point

(44)

OAT (oF)

Unit Capacity Control

Compressor Staging in Cool Mode

The first compressor on the unit is started when evaporator LWT is higher than the target plus the Startup Delta T setpoint.

An additional compressor is started when Evaporator LWT is higher than the target plus the Stage Up Delta T setpoint.

When multiple compressors are running, one will shut down if evaporator LWT is lower than the target minus the Stage Down Delta T setpoint.

All running compressors will shut down when the evaporator LWT is lower than the target minus the Shut Down Delta T setpoint.

Stage Up Delay

A minimum amount of time will pass between compressors starting, which is defined by the Stage Up Delay setpoint. This delay will only apply when at least one compressor is running. If the first compressor starts and quickly fails on an alarm, another compressor will start without this minimum time passing.

Required Load for Stage Up

An additional compressor will not be started until all running compressors are at a capacity higher than the Load Stage Up setpoint, or running in a limited state.

Light Load Stage Down

When multiple compressors are running, one will shut down if all running compressors are at a capacity lower than the Load Stage Down setpoint and the evaporator LWT is less than the target plus the Stage Up Delta T setpoint. A minimum amount of time will pass between compressors stopping as a result of this logic, which is defined by the Stage Down Delay setpoint.

Light Load Shut Down

When the following conditions are met, the last compressor running on the chiller will be shut down:

• One compressor running

• Evaporator Delta T < 0.25*(Nominal Evap Delta T Setpoint/Number of Circuit

Setpoint) for longer than five minutes

• Variable Evap Flow Setpoint = No

Maximum Circuits Running

If the number of compressors running is equal to the Max Circuits Running setpoint, no additional compressors will be started.

When multiple compressors are running, one will shut down if the number of compressors running is more than the Max Circuits Running setpoint.

28 OM 1051-2

Staging Sequence

This section defines which compressor is the next one to start or stop. In general, compressors with fewer starts will normally start first, and compressors with more run hours will normally stop first. Compressor staging sequence can also be determined by an operator defined sequence via setpoints.

Next To Start

The next compressor to start must meet the following requirements:

Lowest sequence number of those compressors available to start

• -if sequence numbers are equal, it must have the least starts

• -if starts are equal, it must have least run hours

• -if run hours are equal, it must be the lowest numbered compressor

Next To Stop

The next compressor to shut down must meet the following requirements:

Lowest sequence number of the compressors that are running

• -if sequence numbers are equal, it must have the most run hours

• -if run hours are equal, it must have the fewest starts

• -if starts are equal, it must be the lowest numbered compressor

Compressor Capacity Control in Cool Mode

In Cool mode, evaporator LWT is controlled to a temperature within a calculated variation range of the target under constant flow conditions by controlling capacity of the individual compressors. The allowed variation is plus or minus 4% of nominal evaporator delta t.

Compressors are loaded with a fixed step scheme. The rate of capacity adjustment is determined by the time between capacity changes. The farther away from the target, the faster compressors will be loaded or unloaded.

The logic projects ahead to avoid overshoot, such that the overshoot does not cause the unit to shut off due to evaporator LWT dropping below the target minus the Shutdown Delta T setpoint while there is still a load on the loop at least equal to the minimum unit capacity.

Capacity of the compressors is controlled so that when possible their capacities are balanced.

Circuits that are running in manual capacity control or running with active capacity limiting events are not considered in the capacity control logic.

The compressor capacities are adjusted one at a time while maintaining a capacity imbalance that does not exceed 12.5%.

Load/Unload Sequence

This section defines which compressor is the next one to load or unload.

Next To Load

The next compressor to load meets the following requirements:

Lowest capacity of the running compressors that can load up

• if capacities are equal, it must have the lowest sequence number of the compressors

that are running

• if the sequence numbers are equal, it must have the least starts

• if run starts are equal, it must have the least hours

• if starts hours are equal, it must be the lowest numbered compressor

OM 1051-2 29

Next To Unload

The next compressor to unload must meet the following requirements:

Highest capacity of the running compressors

• if capacities are equal, it must have the lowest sequence number of the compressors

that are running

• if sequence numbers are equal, it must have the most run hours

• if run hours are equal, it must have the least starts

• if starts are equal, it must be the lowest numbered compressor

Compressor Capacity Control in Ice Mode

In Ice mode, running compressors are loaded up simultaneously at the maximum possible rate that allows for stable operation of the individual circuits.

Unit Capacity Overrides

Unit capacity limits are used to limit total unit capacity in Cool mode only. Multiple limits may be active at any time, and the lowest limit is always used in the unit capacity control.

Soft load, demand limit, and network limit use a deadband around the actual limit value, such that unit capacity increase is not allowed within this deadband. If unit capacity is above the deadband, capacity is decreased until it is back within the deadband.

• For 2 circuit units, the deadband is 7%.

• For 3 circuit units, the deadband is 5%.

Soft Load

Soft Loading is a configurable function used to ramp up the unit capacity over a given time. The setpoint that control this function are:

• Soft Load – (ON/OFF)

• Begin Capacity Limit – (Unit %)

• Soft Load Ramp – (seconds)

The Soft Load Unit Limit increases linearly from the Begin Capacity Limit set-point to 100% over the amount of time specified by the Soft Load Ramp set-point. If the option is turned off, the soft load limit is set to 100%.

Demand Limit

The maximum unit capacity can be limited by a 4 to 20 mA signal on the Demand Limit analog input, usually from a BAS, on the unit controller. This function is only enabled if the Demand Limit setpoint is set to ON and the control is in the COOL mode.

As the signal varies from 4 mA up to 20 mA, the maximum unit capacity changes from 100% to 0%. The unit capacity shall be adjusted as needed to meet this limit, except that the last running compressor cannot be turned off to meet a limit lower than the minimum unit capacity.

Network Limit

The maximum unit capacity can be limited by a network signal. This function is only enabled if the unit control source is set to network. The signal will be received through the BAS interface on the unit controller.

As the signal varies from 0% up to 100%, the maximum unit capacity changes from 0% to 100%. The unit capacity is adjusted as needed to meet this limit, except that the last running compressor cannot be turned off to meet a limit lower than the minimum unit capacity.

30 OM 1051-2

Current Limit

unload area

Unload area

Current Limit control is enabled only when the current limit enable input is ON.

Unit current is calculated based on the 4-20 mA input that receives a signal from an external device. The current at 4 mA is assumed to be 0, and the current at 20 mA is defined by a setpoint. As the signal varies from 4 to 20 mA, the calculated unit current varies linearly from 0 amps to the amp value defined by the setpoint.

The current limit uses a deadband centered around the actual limit value, such that unit capacity increase is not allowed when current is within this deadband. If unit current is above the deadband, capacity is decreased until it is back within the deadband. The current limit deadband is 5% of the current limit.

Figure 9, Current Limit Operation

Current Limit

Hold area

5% of HMI setpoint

Free to load or

Maximum LWT Pulldown Rate

The maximum rate at which the leaving water temperature can drop is limited by the Maximum Rate setpoint, only when the LWT is less than 59°F (15°C).

If the pulldown rate is higher than the Maximum Pulldown Rate set point minus 0.1°C, the unit capacity should not be increased.

If the pulldown rate is higher than the Maximum Pulldown Rate set point plus 0.1°C, the unit capacity should be reduced until the rate is less than that value.

High Water Temperature Capacity Limit

If the evaporator LWT exceeds 77°F (25°C), compressor load will be limited to a maximum of 80%. Compressors will unload to 80% or less if running at greater than 80% load when the LWT exceeds the limit. This feature is to keep the circuit running within the capacity of the condenser coil.

Pumpdown

The circuit state should be Pump down when any of the following conditions are true.

1. Normal shut down alarm exists in Run state.

2. LWT error is less than Shut down delta T in case of 1 circuit running

3. LWT error is less than Stage down delta T in case of 2 circuit running

4. Unit state is Pumpdown

5. Circuit switch is Off

OM 1051-2 31

Cycle Timer

A minimum time between starts of the compressor and a minimum time between shutdown and start of the compressor shall be enforced.

The time values are set by global circuit setpoints. These cycle timers shall be enforced even through cycling of power to the chiller.

These timers may be cleared via a setting on the HMI.

Start-to-start time is the time period from when a compressor starts until it starts again.

Stop-to-start is the time period from when a compressor stops until it restarts.

Table 6, Cycle Time Settings

Function Default

Start - Start time 20 min 15 min 60 min

Stop - Start time 5 min 3 min 20 min

minimum maximum

Range

Circuit Start-up Delta T, Shut-down Delta T

To avoid excessive ON/OFF compressor cycling when the capacity required is very low.

The first compressor on the unit will be started when evaporator LWT is higher than the LWT target plus the Startup Delta T setpoint.

An additional compressor will be started when evaporator LWT is higher than the target plus the Stage Up Delta T setpoint.

When multiple compressors are running, one will shut down if Evaporator LWT is lower than the target minus the Stage Down Delta T setpoint.

All running compressors will shut down when the evaporator LWT is lower than the target minus the Shut Down Delta T setpoint.

Circuit Pulldown Rate

The pulldown rate is established to control the capacity of the compressor so that it does not pull down the chilled water temperature too fast and overshoot the LWT target and to avoid excessive compressor cycling.

The maximum rate at which the leaving water temperature can drop is limited by the Maximum Rate setpoint, only when the LWT is less than 15°C (59°F).

If the pulldown rate is higher than the Maximum Pulldown Rate setpoint minus 0.1°C, the unit capacity will not be increased.

If the pulldown rate is higher than the Maximum Pulldown Rate setpoint plus 0.1°C, the unit capacity will be reduced until the rate is less than that value.

Non-VFD models

EWT slope is calculated such that the slope represents the estimated change in EWT over a time frame of one minute. This slope is used to determine the compressor capacity

VFD models

Compressor capacity is controlled by compressor speed and a sophisticated algorithm is used to determine rate.

32 OM 1051-2

Unit Capacity Control

Non-VFD models

An estimate of total unit capacity is needed for applying unit capacity limits. Unit capacity will be based on the estimated circuit capacities.

The unit capacity is the average of the estimated circuit capacities.

The logic will project ahead to avoid overshoot, such that the overshoot does not cause the unit to shut off due to evaporator LWT dropping below the target minus the Shutdown Delta T setpoint while there is still a load on the loop at least equal to the minimum unit capacity.

Capacity of the compressors is controlled so that when possible their capacities are balanced.

Circuits that are running in manual capacity control or running with active capacity limiting events are not considered in the capacity control logic.

The compressor capacities are adjusted one at a time while maintaining a capacity imbalance that does not exceed 12.5%.

VFD models

The purpose of this logic is as follows.

• To avoid load/unload hunting.

• To reach LWT target at appropriate speed.

• To avoid unnecessary shut downs.

• To keep LWT within +/-0.1C of LWT target as possible.

Compressor capacity is controlled by compressor speed and a sophisticated algorithm is used to determine the rate considering the various parameters affecting capacity.

OM 1051-2 33

Circuit Functions

Calculations

Refrigerant Saturated Temperature

Refrigerant saturated temperature is calculated from the pressure sensor readings for each circuit. A function provides the converted value of temperature to match values published data for R134a:

-within 0.18°F (0.1°C) for pressure inputs from 0 to 300 psi (0 to 2070kPa)

-within 0.36°F (0.2°C) for pressure inputs from -11.6 to 0 psi (80 kPa to 0 kPa)

Evaporator Approach

The evaporator approach is calculated for each circuit. The equation is as follows:

Evaporator Approach = LWT – Evaporator Saturated Temperature

Condenser Approach

The condenser approach is calculated for each circuit. The equation is as follows:

Condenser Approach = Condenser Saturated Temperature - OAT

Suction Superheat

Suction superheat is calculated for each circuit using the following equation:

Suction superheat = Suction Temperature – Evaporator Saturated Temperature

Discharge Superheat

Discharge superheat is calculated for each circuit using the following equation:

Discharge superheat = Discharge Temperature – Condenser Saturated Temperature

Oil Differential Pressure

Oil Differential Pressure is calculated for each circuit with this equation:

Oil Differential Pressure = Condenser Pressure - Oil Pressure

Maximum Saturated Condenser Temperature

The maximum saturated condenser temperature calculation is modeled after the compressor operational envelope.

If Sat Evap Temp < 32°F (0°C) then Max Sat Cond Temp = 1.596(Sat Evap Temp) +155°F (68.3°C)

Otherwise, Max Sat Cond Temp = 155°F (68.3°C)

High Saturated Condenser – Hold Value

High Cond Hold Value = Max Saturated Condenser Value – 5°F (2.78°C)

High Saturated Condenser – Unload Value

High Cond Unload Value = Max Saturated Condenser Value – 3°F (1.67°C)

Condenser Saturated Temperature Target

The saturated condenser temperature target is calculated by using the following equation:

Sat condenser temp target raw = 0.8332(evaporator sat temp) + 95.0°F (35.0 °C)

This value is then limited to a range defined by the Condenser Saturated Temperature Target min and max setpoint. These setpoint simply cut off the value to a working range, and this range can be limited to a single value if the two setpoint are set to the same value.

34 OM 1051-2

Circuit Control Logic

Circuit Availability

A circuit is available to start if the following conditions are true:

• Circuit switch is closed

• No circuit alarms are active

• Circuit Mode setpoint is set to Enable

• BAS Circuit Mode setpoint is set to Auto

• No cycle timers are active

• Discharge Temperature is at least 9°F (5°C) higher than Oil Saturated Temperature

Starting

The circuit will start if all these conditions are true:

• Adequate pressure in the evaporator and condenser (see No Pressure At Start Alarm)

• Circuit Switch is closed

• Circuit Mode setpoint is set to Enable

• BAS Circuit Mode setpoint is set to Auto

• No cycle timers are active

• No alarms are active

• Staging logic requires this circuit to start

• Unit state is Auto

• Evaporator pump state is Run

Circuit Startup Logic

Circuit startup is the time period following the starting of the compressor on a circuit. During the startup, the low evaporator pressure alarm logic is ignored. When the compressor has been running at least 20 seconds and the evaporator pressure rises above the low evaporator pressure unload setpoint, the startup is complete.

If the pressure does not rise above the unload setpoint and the circuit has been running longer than the Startup Time setpoint, then the circuit is turned off and an alarm triggered. If the evaporator pressure drops below the absolute low pressure limit then the circuit is turned off and the same alarm triggered.

Low OAT Restart Logic

Low OAT restart logic allows multiple start attempts in low ambient conditions. If the condenser saturated temperature is less than 60°F (14.6°C) when the compressor starts, the startup is considered to be a ‘low OAT start’. If a low OAT start is not successful the circuit is shut down, but no alarm is triggered for the first two attempts of the day. If a third low OAT start attempt fails, then the circuit is shut down and the Low OAT Restart Alarm is triggered.

The restart counter is reset when a startup is successful or the Low OAT Restart alarm is triggered.

Stopping

Normal Shutdown

A normal shutdown requires the circuit to pumpdown before the compressor is turned off. This is done by closing the EXV, and closing the liquid line solenoid (if present) while the compressor is running.

OM 1051-2 35

The circuit will do a normal shutdown (pumpdown) if any of the following are true:

• Staging logic requires this circuit to stop

• Unit State is Pumpdown

• A pumpdown alarm occurs on the circuit

• Circuit switch is open

• Circuit Mode setpoint is set to Disable

• BAS Circuit Mode setpoint is set to Off

The normal shutdown is complete when any of the following are true:

• Evaporator Pressure is less than the Pumpdown Pressure setpoint

• Service Pumpdown setpoint is set to Yes and Evaporator Pressure is less than

5 psi (34.5 kPa)

• Circuit has been pumping down for longer than the Pumpdown Time Limit setpoint

Rapid Shutdown

A rapid shutdown requires the compressor to stop and the circuit to go to the Off state immediately.

The circuit will do a rapid shutdown if either of these conditions occurs at any time:

• Unit State is Off

• A rapid stop alarm occurs on the circuit

Circuit Status

The displayed circuit status is determined by the conditions in the following table:

Table 7, Circuit Status

Enum Status Conditions

0 Off:Ready Circuit is ready to start when needed.

1 Off:Stage Up Delay Circuit is off and cannot start due to stage up delay.

2 Off:Cycle Timer Circuit is off and cannot start due to active cycle timer. 3 Off:BAS Disable Circuit is off and cannot start due to BAS command. 4 Off:Keypad Disable Circuit is off and cannot start due to keypad disable.

5 Off:Circuit Switch Circuit is off and circuit switch is off.

6 Off:Refr In Oil Sump

7 Off:Alarm Circuit is off and cannot start due to active circuit alarm.

8 Off:Test Mode Circuit is in test mode.

9 EXV Preopen Circuit is in preopen state.

10 Run:Pumpdown Circuit is in pumpdown state.

11 Run:Normal Circuit is in run state and running normally.

12 Run:Disch SH Low

13 Run:Evap Press Low

14 Run:Cond Press High

15 Run: High LWT Limit

16 Run: High VFD Amps

17 Off: Max Comp Starts

Circuit is off and Discharge Temperature – Oil Saturated Temperature at gas pressure <= 5°C

Circuit is running and cannot load due to low discharge superheat. Circuit is running and cannot load due to low evaporator pressure. Circuit is running and cannot load due to high condenser pressure. Circuit is running and cannot load due to high evaporator leaving water temperature. Circuit is running and cannot load due to high compressor VFD current output. Circuit is off and cannot start due to four starts in the last hour. Remaining time displayed.

36 OM 1051-2

Compressor Control

The compressor runs only when the circuit is in a start, run or pumpdown state. The compressor will not be running any time the circuit is off or during preopening the EXV.

Compressor State

The compressor will always be in one of the following states

Name Meaning

Off Comp off.

Start Comp in Start control.

Run Comp in automatic or manual capacity control.

Pump down Comp in shut down control.

Compressor Off

The control state will be Off when the circuit state is Off.

Compressor Start

The purpose of this logic is:

• To avoid the suction pressure dropping too much at start.

• To prohibit loading until circuit state is stable.

The control state should be Start up when the circuit state is Start. Start up is controlled by logic considering EXV preopen time, compressor start time, suction superheat and other parameters.

Capacity Control, Non-Compressor VFD Models

After starting, the compressor capacity target should be the minimum of 10%, and no attempt to increase compressor capacity should be made until the compressor has been running at least three minutes and the minimum discharge superheat has been established for at least 30 seconds. After this condition is met, the compressor capacity target shall move via steps to a minimum running capacity even if unit capacity control commands do not require the compressor to load up. This minimum running capacity target is 26% for European chillers and 25% for US chillers.

Once the compressor has been loaded to the minimum running capacity target, the capacity target shall always be at least equal to this value while the compressor is running.

Changes to the capacity target shall be performed as needed to meet unit capacity requirements based on load and unload commands (see unit capacity control section). For European chillers, the standard capacity target step is 4%, and for US chillers it is 5%.

A minimum time of 20 seconds should pass between capacity changes other than the capacity transitions from 50% to 60% or from 60% to 50%. For those capacity transitions, a minimum time of 30 seconds should pass before capacity is changed again.

OM 1051-2 37

Capacity Control, Compressor VFD Models

   

The control state is Capacity control when the circuit state is Run.

The purpose of this logic is as follows.

• To avoid the unnecessary shut down due to excessive loading.

• In the high LWT area, the loading should be faster.

• When the DSH is low, it could be an abnormal situation, so the loading should be limited.

Load control

Comp will Load when all the following is true.

• LWT error > Keep dead band

• EWT Pd Rate < EWT Pd Rate limit

•

DSH > 12C for 30sec at least

Unload control Compressor will Unload when any of the following conditions are true

• LWT error < minus Keep dead band

• HP > HP_unload

• LP < LP_unload

• EWT Pd Rate > EWT Pd Rate for unload

•

Inverter over current unload

Manual capacity control

This function is only for use by authorized service personnel and a special password is requires for access.

Condenser Fan Control

The compressor must be running in order to stage fans on. All running fans will turn off when compressor goes to the Off state.

Saturated Condenser Temperature Target

The saturated condenser temperature target is calculated by first using the following equation:

Sat condenser temp target raw = 0.8332(suction sat temp) + 63.6°F (35.0°C)

Fan Control without VFD

The fan stage is adjusted in steps of 1 fan. Fan staging will accommodate anywhere from 5 to 12 fans per circuit according to the following table:

Output Number

1 2 3 4 5 6

                                    

# of fans

5 6 7 8

9 10 11 12

38 OM 1051-2

Figure 10, Fan Staging Up and Down

If this error accumulation is greater than 5.0 deg F (2.8 deg C), then fan stage down.

If this error accumulation is greater than 19.8 deg F (11 deg C) then stage up.

(Target) + (fan stage up dead band)

Target discharge saturated temp

(Target) - (fan stage down dead band)

Referring to Figure 10, a fan will run normally when the saturated discharge temperature (equivalent to discharge pressure) is between the Target Temperature plus the stage up deadband and minus the stage down deadband.

If the saturated temperature exceeds the stage up or stage down setting, an error accumulation is calculated. The error accumulation takes into account how great the error is and its duration. Thusly, a small error can exist for a relatively long time and a large error for a relatively short time before a fan is staged on or off.

If the saturated temperature returns to within the deadband area, the error accumulation is cleared.

Staging Up

Six stage-up deadbands are used. Stages one through five use their respective dead bands. Stages six through twelve all use the sixth stage up dead band.

When the saturated condenser temperature is above the Target + the active deadband, a Stage Up error is accumulated.

Stage Up Error Step = Saturated Cond. temperature – (Target + Stage-Up deadband)

The Stage Up Error Step is added to Stage Up Accumulator once every 5 seconds, only if the Saturated Condenser Refrigerant Temperature is not falling. When Stage Up Error Accumulator is greater than 19.8°F (11°C) another stage is added.

If the circuit is configured to have a VFD on the first fan, then the first fan will turn on when condenser temperature is above the target.

When a stage up occurs or the saturated condenser temperature falls back within the Stage Up dead band the Stage Up Accumulator is reset to zero.

Staging Down

Five stage down dead bands are used. Stages two through five use their respective dead bands. Stages six through twelve all use the stage six dead band.

OM 1051-2 39

When the saturated condenser refrigerant temperature is below the Target – the active deadband, a Stage Down error is accumulated.

Stage Down Error Step = (Target - Stage Down dead band) - Saturated Condenser Refrigerant temperature

The Stage Down Error Step is added to Stage Down Accumulator once every 5-second Stage Down Error Delay seconds. When the Stage Down Error Accumulator is greater than 37°F (2.8°C) another stage of condenser fans is removed.

When one fan is running, a fixed point is used in place of a deadband. When the Saturated Condenser temperature drops below 70°F (21.1°C), stage down error is accumulated.

Fan Control with VFD

Condenser pressure trim control is accomplished using an optional VFD on the first fan. This VFD control varies the fan speed to drive the saturated condenser temperature to a target value. The target value is normally the same as the saturated condenser temperature target.

VFD State

The VFD speed signal is always 0 when the fan stage is 0. When the fan stage is greater than 0, the VFD speed signal is enabled and controls the speed as needed.

Stage Up Compensation

In order to create a smoother transition when another fan is staged on, the VFD compensates by slowing down initially.

This is accomplished by adding the new fan stage up deadband to the VFD target. The higher target causes the VFD logic to decrease fan speed.

Then, every 2 seconds, 0.1°C is subtracted from the VFD target until it is equal to the saturated condenser temperature target set point.

This will allow the VFD to slowly bring the saturated condenser temperature back down.

EXV Control

The EXV is moved at a rate of 150 steps per second, with a total range of 3810 steps. Positioning is determined as described in the following sections, with adjustments made in increments of 0.1% of the total range.

Closed Position

When the EXV enters the closed state, it should be reinitialized to maintain accurate positioning.

If the unit is configured for use without liquid line solenoid valves, the EXV position is 0% any time the EXV is in a closed state.

If the unit is configured for use with liquid line solenoid valves, the EXV position will be 0% when the EXV initially enters the closed state, while it is reinitializing to the zero position. After the EXV position command has been 0% for a minute, the EXV will be moved to 5% (to prevent excessive pressure buildup between EXV and liquid line solenoid valve).

Preopen Operation

Preopen operation will vary depending on the unit configuration. The unit will be configured for use with or without liquid line solenoid valves via a setpoint.

40 OM 1051-2

Without Liquid Line Solenoid Valves

The EXV control will open the EXV to 5% for 5 seconds before the compressor is started.

With Liquid Line Solenoid Valves

If evaporator pressure is less than condenser pressure when a circuit start is required, the EXV control will preopen the EXV to 50% for 15 seconds. Otherwise, the preopen time will be 0 (position is already 5%).

Pressure Control Operation

In pressure control, the EXV is positioned to control the evaporator pressure. The pressure target varies based on evaporator LWT and discharge superheat values.

The base target is limited to a range from the low pressure inhibit setpoint plus 2 psi (14 kPa), up to 50.7 psi (350 kPa).

The pressure control target may be adjusted if the discharge superheat is not within an acceptable range. If the superheat is less than 21.6°F (12°C), the pressure target will be reduced. If the superheat is more than 39.6°F (22°C), the pressure target will be increased. The adjusted target is limited to a range from the low pressure inhibit setpoint plus 2 psi (14 kPa), up to 50.7 psi (350 kPa).

When the EXV transitions from superheat control to pressure control, the target will start at the current evaporator pressure value. The pressure target will then be decreased until reaching the normal calculated target, at a rate of 0.43 psi (3 kPa) per second. If the pressure at transition is less than the calculated target, then pressure control will start immediately with the calculated target.

When the EXV transition from preopen to pressure control, the target starts at the minimum and is held there for three minutes. After that time, the target is increased until it meets the calculated target, at a rate of 0.43 psi (3 kPa) per second.

The EXV should control the evaporator pressure to within 1.0 psi (7 kPa) of the target during stable operating conditions (stable water loop, static compressor capacity, and stable condensing temperature).

Superheat Control Operation

In superheat control, the EXV is positioned to control suction superheat. The superheat target varies linearly from 5 to 9.9 °F (2.8 to 5.5 °C) as discharge superheat changes from

30.6 to 21.6 °F (17 to 12 °C). This target is constantly updated, and averaged over a 10 second period.

When the EXV transitions to the superheat control state, the target will start at the current suction superheat value. This target will then be decreased 0.18°F (0.1°C) every five seconds until reaching the normal calculated target.

The EXV should control the suction superheat to within 1.5°F (0.8°C) of the target during stable operating conditions (stable water loop, static compressor capacity, and stable condensing temperature).

Control State Transitions

When the circuit is required to start, the EXV will go into the Preopen control state. After being in this state for the time period required, the EXV can transition to Pressure Control. The compressor will start at the same time that this occurs.

While the circuit is in a run state, the EXV will always be in either Pressure Control or Superheat Control. The transition from Pressure Control to Superheat Control requires all of the following:

• Evap LWT <= 59.9°F (15.5°C)

OM 1051-2 41

• Suction Superheat >= suction superheat target

• EXV control state has been in pressure control and discharge superheat >= 12°C

(21.6°F) for at least 3 minute

• Low Evap Pressure Unload alarm is not active

The transition from Superheat Control to Pressure Control will occur if any of the following conditions exist:

• Discharge Superheat < 12°C (21.6°F)

• Evap LWT > 17°C (62.6°F)

Any time the circuit is in the Off state or Pumpdown state, the EXV should be in the closed position.

Response to Compressor Capacity Change

The logic will consider transition from 50% to 60% and from 60% to 50% as special conditions. During this time, the EXV will operate in a way that prevents over-feeding or under-feeding the evaporator such that adequate superheats are maintained following the transition, no liquid ingestion by the compressor occurs, and no evaporator pressure dip causes low pressure alarms.

Minimum Operating Position

Whenever the compressor is running and the circuit is not pumping down, the EXV position is limited to a minimum of 5%.

Auto Control

When the EXV is in auto control and the EXV control state is either pressure control or superheat control, the position will be adjusted using a PID function. This function should control the pressure or superheat as outlined in the preceding sections.

The compressor size setting will adjust the proportional factor of the PID when in superheat control to allow for stable control of the superheat.

Manual Control

The EXV position can be set manually. Manual control can only be selected when the EXV state is Pressure or Superheat control. At any other time, the EXV control setpoint is forced to auto.

When EXV control is set to manual, the EXV position is equal to the manual EXV position setting. If set to manual when the circuit state transitions from run to another state, the control setting is automatically set back to auto. If EXV control is changed from manual back to auto while the circuit state remains run, the EXV state will go back to the normal operations if possible or to pressure control to limit maximum operating pressure.

Economizer Control

Non-VFD: The circuit economizer will be activated when the circuit is in a run state and the capacity exceeds 95%. It will turn back off when either the load drops below 80% or the circuit is no longer in a run state.

Compressor VFD: The economizer is on any time the circuit is running.

Liquid Injection

Liquid injection will be activated when the circuit is in a run state and the discharge temperature rises above the Liquid Injection Activation setpoint.

Liquid injection will be turned off when the discharge temperature decreases below the activation setpoint by a differential of 27°F (15°C).

42 OM 1051-2

Liquid Line Solenoid Valve

The liquid line solenoid valve output will be on any time the circuit is in the Start or Run state. It will be off when the circuit is in the Off, Preopen, or Pumpdown states.

Capacity Overrides – Limits of Operation

The following conditions will override automatic capacity control as described. These overrides keep the circuit from entering a condition in which it is not designed to run.

Low Evaporator Pressure

This limit is to be applied only when the chiller is operating in COOL mode.

If the Low Evaporator Pressure Hold alarm is triggered, the compressor will not be allowed to increase in capacity.

If the Low Evaporator Pressure Unload alarm is triggered, the compressor will begin reducing capacity.

The compressor will not be allowed to increase in capacity until the Low Evaporator Pressure Hold alarm has cleared.

See the Circuit Alarms section for details on triggering, reset, and unloading action.

High Condenser Pressure

This limit is to be applied only when the chiller is operating in COOL mode.

If the High Condenser Pressure Hold alarm is triggered, the compressor will not be allowed to increase capacity.

If the High Condenser Pressure Unload alarm is triggered, the compressor will begin reducing capacity.

The compressor will not be allowed to increase in capacity until the High Condenser Pressure Hold alarm has cleared.

See the Circuit Alarm section for details on triggering, reset, and unloading action.

High Water Temperature Capacity Limit

If the evaporator LWT is 25°C (77°F) or higher, compressor capacity will be limited to a maximum of 80%. Compressors should unload to 80% or less if running at greater than 80% capacity when the LWT exceeds 25°C (77°F).

OM 1051-2 43

Alarms and Events

Situations may arise that require some action from the chiller, or that should be logged for future reference. Alarms are classified in the following sections per the Global Chiller Protocol Standard using the Fault/Problem/Warning scheme.

When any Unit Fault Alarm is active, the alarm digital output will be turned on. If no Unit Fault Alarm is active, but any Circuit Fault Alarm is active, the alarm digital output will alternate five seconds on and five seconds off constantly. In addition, if a Circuit Fault Alarm is active, the circuit alarm output for that circuit will be turned on.

Signaling Alarms

The following actions will signal that an alarm has occurred:

1. The unit or a circuit will execute a rapid or pumpdown shutoff.

2. An alarm bell icon  will be displayed in the upper right-hand corner of all controller

screens including the optional remote user interface panel’s screens.

3. An optional field supplied and wired remote alarm device will be activated.

Clearing Alarms/Faults

Active alarms can be cleared through the keypad/display or a BAS network. Alarms are automatically cleared when controller power is cycled. Alarms are cleared only if the conditions required to initiate the alarm no longer exist. All alarms and groups of alarms can be cleared via the keypad or network via LON using nviClearAlarms and via BACnet using the ClearAlarms object.

To use the keypad, follow the Alarm links to the Alarms screen, which will show Active Alarms and Alarm Log. Select Active Alarm and press the wheel to view the Alarm List (list of current active alarms). They are in order of occurrence with the most recent on top. The second line on the screen shows Alm Cnt (number of alarms currently active) and the status of the alarm clear function. Off indicates that the Clear function is off and the alarm is not cleared. Press the wheel to go to the edit mode. The Alm Clr (alarm clear) parameter will be highlighted with OFF showing. To clear all alarms, rotate the wheel to select ON and enter it by pressing the wheel.

An active password is not necessary to clear alarms.

If the problem(s) causing the alarm have been corrected, the alarms will be cleared, disappear from the Active Alarm list and be posted in the Alarm Log. If not corrected, the On will immediately change back to OFF and the unit will remain in the alarm condition.

Remote Alarm Signal

The unit is configured to allow field wiring of a remote alarm device. See Figure 18 on page 71 for field wiring information.

44 OM 1051-2

Description of Alarms

Introduction

The alarms have the following conventions:

ALARM, any condition outside of normal operation requiring some action on the part of the control or information useful to the operator or to be logged for future reference

WARNING, an alarm indicating a condition that is not critical to safe unit operation, but is worthy of note and/or logging.

PROBLEM, a alarm that indicates operation off normal and requires some action by the control such as unloading a compressor.

FAULT, an alarm with consequences serious enough to require a compressor, a circuit, or entire unit to shutdown. The shutdown may be rapid, bypassing the pumpdown cycle, or controlled and incorporate the pumpdown cycle.

Alarm description conventions:

• CnCmpn OffMechPressLo, the Cn is the circuit number; the Cmpn is the

compressor number.

• UnitOff EvapWaterFlow, UnitOff refers to the entire unit.

Alarm Listing

The alarms are listed alphabetically below showing their location

BadLWTResetInput, Alarm 11, page 48

BadSetptOverrideInput, Alarm 12, page 49

CnCmpnInhbtLdAmpsHi, Alarm 45, page 55

CnCmpnOffCondPressHi, Alarm 17, page 50

CnCmpnOffCondPressSen, Alarm 32, page 53

CnCmpnOffDishTempSen, Alarm 36, page 53

CnCmpnOffDischTmpHi, Alarm 20, page 50

CnCmpOffEvpPressSen, Alarm 32, page 52

CnCmpn OffLowDischSH, Alarm 39, page 53

CnCmpnOffMechPressHi, Alarm 19, page 50

CnCmpnOffMotorTempHi, Alarm 24, page 51

CnCmpnOffMtrTempSen, Alarm37, page 53

CnCmpOffNoPressAtStart, Alarm 27, page 52

CnCmpnOff NoPressChgStart, Alarm 25, page 51

CnCmpOffOilFeedSen, Alarm 34, page 53

CnCmpnOffOilPrDiffHi, Alarm 21, page 50

CnCmpnOffPrRatioLo, Alarm 18, page 50

CnCmpn OffSlidePosSen, Alarm 38, page 53

CnCmpnOffStarterFlt, Alarm 22, page 51

CnCmpnOffSuctTempSen, Alarm 35, page 53

CnCmpOffVfdCommFail, Alarm 30, page 52

CnCmpnOffVfdFault, Alarm 23, page 51

CnCmpnOffVfdTempHi, Alarm 29, page 52

CnCmpnUnloadAmpsHi, Alarm 44, page 55

OM 1051-2 45

CnFailedPumpdown, Alarm 46, page 55

CnInhibitLoadCndPrHi, Alarm 42, page 54

CnInhibitLoadEvpPrLo, Alarm 40, page 54

CnLowOATRestartFault, Alarm 26, page 51

CnLowPressureStartFail, Alarm 16, page 50

CnOffCmpCtrlComFail, Alarm 28, page 52

CnOffEXVCtrlComFail, Alarm 28, page 52

CnOffPhaseVoltage, Alarm 14, page 49

CnPwrLossRun, Alarm 47, page 55

CnUnloadEvppressLo, Alarm 41, page 54

CnUnloadCndpressHi, Alarm 43, page 54

CompOffEvapPressLo, Alarm 15, page 49

StartInhbtAmbTempLo, Alarm 13, page 49

UnitExternalEvent, Alarm 10, page 48

UnitOffAmbTempSen, Alarm 6, page 48

UnitOffEmergencyStop, Alarm 8, page 48

UnitOffEvpEntWTempSen, Alarm 5, page 48

UnitOffEvpLvgWTempSen, Alarm 4, page 47

UnitOffEvapWaterFlow, Alarm 1, page 47

UnitOffEvapWaterTmpLo, Alarm 2, page 47

UnitOffEvpWTempInvrtd, Alarm 3, page 47

UnitOffExternal Alarm, Alarm 7, page 48

UnitOffPhaseVoltage, Alarm 14, page 49

UnitPowerRestore, Alarm 9, page 48

46 OM 1051-2

Unit Faults

Alarm 1, Evaporator Flow Loss

Alarm description (as shown on screen): UnitOffEvapWaterFlow

Trigger:

1: Evaporator Pump State = Run AND Evaporator Flow Digital Input = No Flow

for time > Flow Proof Setpoint AND at least one compressor running

2: Evaporator Pump State = Start for time greater than Recirc Timeout Setpoint and

all pumps have been tried

Action Taken: Rapid stop all circuits

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command, if active via trigger condition 1: When the alarm occurs due to this trigger, it can auto reset the first two times each day, with the third occurrence being manual reset.

For the auto reset occurrences, the alarm will reset automatically when the evaporator state is Run again. This means the alarm stays active while the unit waits for flow, then it goes through the recirculation process after flow is detected. Once the recirculation is complete, the evaporator goes to the Run state which will clear the alarm. After three occurrences, the count of occurrences is reset and the cycle starts over if the manual reset flow loss alarm is cleared.

If active via trigger condition 2:

If the flow loss alarm has occurred due to this trigger, it is a manual reset alarm.

Alarm 2, Evaporator Water Freeze Protect

Alarm description (as shown on screen): UnitOffEvapWaterTmpLo

Trigger: Evaporator LWT or EWT drops below evaporator freeze protect setpoint.

If the sensor fault is active for either LWT or EWT, then that sensor value cannot trigger the alarm.

Action Taken: Rapid stop all circuits

Reset: This alarm can be cleared manually via the unit controller keypad if the

alarm trigger conditions no longer exist.

Alarm 3, Evaporator Water Temperatures Inverted

Alarm description (as shown on screen): UnitOffEvpWTempInvrtd

Trigger: Evap EWT < Evap LWT - 1 deg C AND at least one circuit is running

AND EWT sensor fault not active AND LWT sensor fault not active for 30 sec

Action Taken: Pumpdown stop on all circuits

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command.

Alarm 4, Leaving Evaporator Water Temperature Sensor Fault

Alarm description (as shown on screen): UnitOffEvpLvgWTempSen

Trigger: Sensor shorted or open

Action Taken: Rapid stop all circuits

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command if the sensor is back in range.

OM 1051-2 47

Alarm 5, Entering Evaporator Water Temperature Sensor Fault

Alarm description (as shown on screen: UnitOffEvpEntWTempSen Trigger: Sensor shorted or open

Action Taken: Pumpdown stop of all circuits

Reset: This alarm can be cleared manually via the unit controller keypad or BAS command if the sensor is back in range.

Alarm 6, Outdoor Air Temperature Sensor Fault

Alarm description (as shown on screen): UnitOffAmbTempSen

Trigger: Sensor shorted or open

Action Taken: Normal shutdown of all circuits

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command if the sensor is back in range.

Alarm 7, External Alarm

Alarm description (as shown on screen): UnitOffExternal Alarm

Trigger: External Alarm/Event input is open for at least 5 seconds and external fault

input is configured as an alarm

Action Taken: Rapid stop of all circuits

Reset: Auto clear when digital input is closed

Alarm 8, Emergency Stop Alarm

Alarm description (as shown on screen): UnitOffEmergencyStop

Trigger: Emergency Stop input is low

Action Taken: Rapid stop of all circuits

Reset: Auto clear when digital input is high

Unit Warnings

The following unit events are logged in the warning log with a time stamp.

Alarm 9, Unit Power Restore

Alarm description (as shown on screen): UnitPowerRestore

Trigger: Unit controller is powered up

Action Taken: none

Reset: none

Alarm 10, External Event

Alarm description (as shown on screen): UnitExternalEvent

Trigger: External Alarm/Event input is open for at least 5 seconds and external fault

is configured as an event

Action Taken: None

Reset: Auto clear when digital input is closed

Alarm 11, Bad Demand Limit Input

Alarm description (as shown on screen): BadDemandLimitInput

Trigger: Demand limit input out of range and demand limit is enabled. For this

alarm out of range is considered to be a signal less than 3mA or more than 21mA

Action Taken: None

Reset: Auto clear when demand limit disabled or demand limit input back in range

for 5 seconds

48 OM 1051-2

Alarm 12, Bad Setpoint Override Input

Alarm description (as shown on screen): BadSetptOverrideInput

Trigger: LWT reset input out of range and LWT reset = 4-20mA. For this alarm out

of range is considered to be a signal less than 3mA or more than 21mA.

Action Taken: None

Reset: Auto clear when LWT reset is not 4-20mA or LWT reset input back in range

for 5 seconds

Alarm 13, Low Ambient Lockout

Alarm description (as shown on screen): StartInhbtAmbTempLo

Trigger: The OAT drops below the low ambient lockout setpoint

Action Taken: Normal shutdown of all running circuits

Reset: The lockout clears when OAT rises to the lockout setpoint plus (4.5°F)

Circuit Faults

All circuit stop alarms require shutdown of the circuit on which they occur. Rapid stop alarms do not do a pumpdown before shutting off. All other alarms will do a pumpdown.

When one or more circuit alarms are active and no unit alarms are active, the alarm output will be switched on and off on 5 second intervals.

Alarm descriptions apply to all circuits, the circuit number is represented by ‘n’ in the description.

Alarm 14, Phase Volts Loss/GFP Fault

Alarm description (as shown on screen): UnitOffPhaseVoltage or CnOff PhaseVoltage

Trigger: PVM input is low and PVM setpoint = Multi Point

Action Taken: Rapid stop unit or circuit

Reset: Auto reset when PVM input is high or PVM setpoint does not equal multi

point for at least 5 seconds

Alarm 15, Low Evaporator Pressure

Alarm description (as shown on screen): CnCmpnOffEvpPressLo

Trigger: [Freezestat trip AND Circuit State = Run] OR Evaporator Press < -10 psi

Freezestat logic allows the circuit to run for varying times at low pressures. The lower the pressure, the shorter the time the compressor can run. This time is calculated as follows:

Freeze error = Low Evaporator Pressure Unload – Evaporator Pressure Freeze time = 70 – 6.25 x freeze error, limited to a range of 20-70 seconds

When the evaporator pressure goes below the Low Evaporator Pressure Unload setpoint, a timer starts. If this timer exceeds the freeze time, then a freezestat trip occurs. If the evaporator pressure rises to the unload setpoint or higher, and the freeze time has not been exceeded, the timer will reset.

The alarm cannot trigger if the evaporator pressure sensor fault is active.

Action Taken: Rapid stop circuit

Reset: The alarm is cleared manually if the evaporator pressure is above 10 psi.

OM 1051-2 49

Alarm 16, Low Pressure Start Fail

Alarm description (as shown on screen): CnOffStrtFailEvpPrLo

Trigger: Circuit state = start for time greater than Startup Time setpoint.

Action Taken: Rapid stop circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command.

Alarm 17, High Condenser Pressure

Alarm description (as shown on screen): CnCmpnOffCondPressHi

Trigger: Condenser Saturated Temperature > Max Saturated Condenser Value for

time > High Cond Delay setpoint.

Action Taken: Rapid stop circuit

Reset: This alarm can be cleared manually via the unit controller keypad.

Alarm 18, Low Pressure Ratio

Alarm description (as shown on screen): CnCmpnOff PrRatioLo

Trigger: Pressure ratio < calculated limit for a time > Low Pressure Ratio Delay

setpoint after circuit startup has completed. The calculated limit will vary from 1.4 to

1.8 as the compressor’s capacity varies from 25% to 100%.

Action Taken: Normal shutdown of circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command.

Alarm 19, Mechanical High Pressure (MHP) Switch

Alarm description (as shown on screen): CnCmpnOffMechPressHi

Trigger: Mechanical High Pressure switch input is low AND Emergency Stop

Alarm is not active. (Opening emergency stop switch kills power to MHP switches). Input must be off for one second before alarm is active.

Action Taken: Rapid stop circuit

Reset: This alarm can be cleared manually via the unit controller keypad if the MHP

switch input is high

Alarm 20, High Discharge Temperature

Alarm description (as shown on screen): CnCmpn OffDischTmpHi

Trigger: Discharge Temperature > High Discharge Temperature setpoint AND

compressor is running. Alarm cannot trigger if temperature sensor fault is active

Action Taken: Rapid stop circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command

Alarm 21, High Oil Pressure Difference

Alarm description (as shown on screen): CnCmpnOffOilPrDiffHi

Trigger: Oil Pressure Differential > High Oil Pressure Differential setpoint for a

time greater than Oil Pressure Differential Delay

Action Taken: Rapid stop circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command

50 OM 1051-2

Alarm 22, Compressor Starter Fault

Alarm description (as shown on screen): CnCmpnOffStarterFlt

Trigger:

If PVM setpoint = None(SSS): any time starter fault input is open If PVM setpoint = Single Point or Multi Point: compressor has been running for at least 14 seconds and starter fault input is open

Action Taken: Rapid stop circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command.

Alarm 23, Compressor VFD Fault

Alarm description (as shown on screen): CnCmpnOffVfdFault

Trigger: VFD is sending a fault status to controller via modbus communications

Action Taken: Shutdown compressor n

Reset: Lookup VFD alarm code to determine why the VFD is faulted. Clear alarm

manually via the unit controller keypad after the VFD fault is fixed.

Alarm 24, High Motor Temperature

Alarm description (as shown on screen): CnCmpnOffMotorTempHi Trigger:

For European chillers - Input value for the motor temperature is 4500 ohms or higher or input is open

For US chillers - Motor Temperature input is open for two seconds delay

Action Taken: Rapid stop circuit

Reset:

For European chillers - This alarm can be cleared manually via the unit controller keypad after input value for motor temperature has been 300 ohms or less for at least 5 minutes.

For US Chillers - This alarm can be cleared manually via the unit controller keypad after Motor Protection input has been closed for at least 5 minutes.

Alarm 25, No Pressure Change After Start

Alarm description (as shown on screen): CnOffNoPressChgStart

Trigger: After start of compressor, at least a 3.6 psi drop in evaporator pressure OR

5 psi increase in condenser pressure has not occurred after 15 seconds

Action Taken: Rapid stop circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command.

Alarm 26, Low OAT Restart Fault

Alarm description (as shown on screen): CnCmpnOffNbrRestarts

Trigger: Circuit has failed three low OAT start attempts

Action Taken: Rapid stop circuit Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command.

OM 1051-2 51

Alarm 27, No Pressure At Startup

Alarm description (as shown on screen): CnOffNoPressAtStart

Trigger: Either Evap Pressure < 35 kPa (5.1 psi) OR Cond Pressure < 35 kPa (5.1

psi) AND Compressor start requested AND circuit does not have a fan VFD

Action Taken: Rapid stop circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command if Evap Pressure < 35 kPa (5.1 psi) and Cond Pressure < 35 kPa (5.1 psi), or circuit is configured for fan VFD.

Alarm 28, CC Comm Failure N Circuit Fault

Alarm description (as shown on screen): CnOffCmpCtrlrComFail or CnOffEXVCtrlrComFail

Trigger: Communication with the compressor or EXV I/O extension module has failed

Action Taken: Rapid stop of affected circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command when communication between main controller and the extension module is working for 5 seconds.

Alarm 29, Compressor VFD Overheat Fault - Shutdown

Alarm description (as shown on screen): CnCmpnOffVfdTempHi

Trigger: VFD heat sink temperature has exceeded 248°F (120°C)

Action Taken: Shutdown compressor n

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command if the VFD heat sink temperature is below the alarm setpoint.

Alarm 30, Comm Error with Compressor VFD - Shutdown

Alarm description (as shown on screen): CnCmpnOffVfdCommFail

Trigger: The controller has failed a predetermined number of Modbus reads or

writes with the VFD

Action Taken: Shutdown compressor n

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command if communications is restored

Alarm 31, Current Overload Trip - Shutdown

Alarm description (as shown on screen): CnCmpnOffCurrentHi

Trigger: VFD output current has exceeded 130% of the compressor RLA.

Action Taken: Shutdown compressor n

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command.

Alarm 32, Evaporator Pressure Sensor Fault

Alarm description (as shown on screen): CnCmpnOffEvpPress Sen

Trigger: When sensor is shorted or open, the alarm should be triggered, with the

following exception. If the evaporator LWT is 30°C (86°F) or higher, the fault should not be triggered due to the input signal reading too high unless the circuit has been running for longer than 90 seconds

Action Taken: Rapid stop circuit

52 OM 1051-2

Reset: This alarm can be cleared manually via the unit controller keypad or BAS command if the sensor is back in range

Alarm 33, Condenser Pressure Sensor Fault

Alarm description (as shown on screen): CnCmpnOffCondPressSen

Trigger: Sensor shorted or open

Action Taken: Rapid stop circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS if

the sensor is back in range.

Alarm 34, Oil Pressure Sensor Fault

Alarm description (as shown on screen): CnCmpnOffOilFeedSen

Trigger: Sensor shorted or open

Action Taken: Normal shutdown of circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS if

the sensor is back in range.

Alarm 35, Suction Temperature Sensor Fault

Alarm description (as shown on screen): CnCmpnOffSuctTempSen

Trigger: Sensor shorted or open. Sensor must be out of range for one second

before alarm is active.

Action Taken: Normal shutdown of circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS if

the sensor is back in range.

Alarm 36, Discharge Temperature Sensor Fault

Alarm description (as shown on screen): CnCmpnOffDishTmpSen

Trigger: Sensor shorted or open

Action Taken: Normal shutdown of circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS if

the sensor is back in range.

Alarm 37, Motor Temperature Sensor Fault

Alarm description (as shown on screen): CnCmpnOffMtrTempSen

Trigger: Sensor shorted

Action Taken: Rapid stop circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS if

the sensor is back in range.

Alarm 38, Slide Position Sensor Fault

Alarm description (as shown on screen): CnCmpnOffSlidePosSen

Trigger: Slide position input out of range and Slide Pos Sens= Yes. For this alarm

out of range is considered to be a signal less than 1mA or more than 23mA.

Action Taken: Normal shutdown of circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command if the sensor is back in range.

Alarm 39, Low Discharge Superheat

Alarm description (as shown on screen): CnCmpn OffLowDischSH

Trigger: Discharge superheat < 12°C (21.6°F) for 20 minutes

OM 1051-2 53

Action Taken: Normal shutdown of circuit

Reset: This alarm can be cleared manually via the unit controller keypad or BAS

command.

Circuit Problems

The following events limit operation of the circuit in some way as described in the Action Taken column. The occurrence of a circuit event only affects the circuit on which it occurred. Circuit events are logged in the event log on the unit controller.

Alarm 40, Low Evaporator Pressure - Hold

Event description (as shown on screen): CnInhbtLoadEvpPrLo

Trigger: This event is not enabled until the circuit startup is complete and the unit

mode is Cool. Then, while running, if evaporator pressure <= Low Evaporator Pressure Hold setpoint the event is triggered. The event is not to be triggered for 90 seconds following the capacity change of the compressor from 50% to 60%.

Action Taken: Inhibit loading.

Reset: While still running, the event will be reset if evaporator pressure > (Low

Evaporator Pressure Hold SP + 2psi). The event is also reset if the unit mode is switched to Ice, or the circuit is no longer in the run state.

Alarm 41, Low Evaporator Pressure - Unload

Event description (as shown on screen): CnUnloadEvpPressLo

Trigger: This event is not enabled until the circuit startup is complete and the unit

mode is Cool. Then, while running, if evaporator pressure <= Low Evaporator Pressure Unload setpoint the event is triggered. The event is not to be triggered for 90 seconds following the capacity change of the compressor from 50% to 60%.

Action Taken: Action Taken: Unload the compressor by decreasing the capacity by one step every 5 seconds until the evaporator pressure rises above the Low Evaporator Pressure Unload setpoint.

Reset: While still running, the event will be reset if evaporator pressure > (Low Evaporator Pressure Hold SP + 2psi). The event is also reset if the unit mode is switched to Ice, or the circuit is no longer in the run state.

Alarm 42, High Condenser Pressure - Hold

Event description (as shown on screen): CnInhbtLoadCndPrHi

Trigger: While the compressor is running and unit mode is Cool, if saturated

condenser temperature >= High Saturated Condenser Hold Value, the event is triggered.

Action Taken: Inhibit loading

Reset: While still running, the event will be reset if saturated condenser

temperature < (High Saturated Condenser Hold Value – 10oF). The event is also reset if the unit mode is switched to Ice, or the circuit is no longer in the run state.

Alarm 43, High Condenser Pressure - Unload

Event description (as shown on screen): CnUnloadCndPressHi

Trigger: While the compressor is running and unit mode is Cool, if saturated

condenser temperature >= High Saturated Condenser Unload Value, the event is triggered.

Action Taken: Unload the compressor by decreasing the capacity by one step every 5 seconds until the evaporator pressure rises above the High Condensing Pressure Unload setpoint.

54 OM 1051-2

Reset: While still running, the event will be reset if saturated condenser temperature < (High Saturated Condenser Unload Value – 10oF). The event is also reset if the unit mode is switched to Ice, or the circuit is no longer in the run state.

Alarm 44, Compressor Motor Current High - Unload

Alarm description (as shown on screen): CnCmpnUnloadAmpsHi

Trigger: VFD output amps exceeds unload setpoint

Action Taken: Unload compressor n

Reset: Automatically resets when the VFD output amps are below 116% of motor

rated load amps for 5 seconds.

Alarm 45, Compressor Motor Current High – Inhibit Load

Alarm description (as shown on screen): CnCmpnInhbtLdAmpsHi

Trigger: VFD output amps exceeds hold setpoint

Action Taken: Compressor n can not increase it’s capacity (must hold at it’s current

capacity).

Reset: Automatically resets when the VFD output amps are below 116% of motor rated load amps for 10 seconds.

Alarm 46, Failed Pumpdown

Event description (as shown on screen): CnFailedPumpdown

Trigger: Circuit state = pumpdown for time > Pumpdown Time setpoint

Action Taken: Shutdown circuit

Reset: N/A

Alarm 47, Power Loss While Running

Event description (as shown on screen): CnPwrLossRun

Trigger: Circuit controller is powered up after losing power while compressor was

running

Action Taken: N/A

Reset: N/A

Alarm Logging

When an alarm occurs, the alarm type, date, and time are stored in the active alarm buffer corresponding to that alarm (viewed on the Alarm Active screens) also in the alarm history buffer (viewed on the Alarm Log screens). The active alarm buffers hold a record of all current alarms.

A separate alarm log stores the last 25 alarms to occur. When an alarm occurs, it is put into the first slot in the alarm log and all others are moved down one, dropping the last alarm. The date and time the alarm occurred are stored in the alarm log.

Event Log

This menu is accessed through the alarm menu. It gives access to the event occurrence over a seven day period and the last occurrence with time and date for:

Unit Power Restore Low Pressure Hold Low Pressure Unload

High Pressure Hold High Pressure Unload High Current Hold

High Current Unload

OM 1051-2 55

Using the Controller

>>>>

Alarm Button

The Unit Controller Operation

Figure 11, Unit Controller

Menu Button

Navigation Wheel

Display

The keypad/display consists of a 5-line by 22-character display, three buttons (keys) and a “push and roll” navigation wheel. There is an Alarm Button, Menu (Home) Button, and a Back Button. The wheel is used to navigate between lines on a screen (page) and to increase and decrease changeable values when editing. Pushing the wheel acts as an Enter Button and will jump from a link to the next set of parameters.

56 OM 1051-2

Figure 12, Typical Screen

♦6

Status/Settings Set Up

Temperature

Date/Time/Schedule

Generally, each line on the display contains a menu title, a parameter (such as a value or a setpoint), or a link (which will have an arrow in the right of the line) to a further menu. The first line visible on each display includes the menu title and the line number to which the cursor is currently “pointing”, in the above case 3, Temperature.

The left most position of the title line includes an “up” arrow ▲ to indicate there are lines (parameters) “above” the currently displayed line; and/or a “down” arrow ▼ to indicate there are lines (parameters) “below” the currently displayed items or an “up/down” arrow

♦

to indicate there are lines “above and below” the currently displayed line. The selected

line is highlighted.

View/Set Unit 3

Each line on a screen can contain status-only information or include changeable data

Enter Password

>>>>

fields (setpoints).

When the cursor is on a line the highlights will look like this:

If line contains a changeable value-

If the line contains status-only information-

Or a line in a menu may be a link to further menus. This is often referred to as a jump line, meaning pushing the navigation wheel will cause a “jump” to a new menu. An arrow ( displayed to the far right of the line to indicate it is a “jump” line and the entire line is highlighted when the cursor is on that line.

NOTE - Only menus and items that are applicable to the specific unit configuration are displayed.

This manual includes information relative to the operator level of parameters; data and setpoints necessary for the every day operation of the chiller. There are more extensive menus available for the use of service technicians.

Evaporator Delta T= 10.0F

Unit Status= Run

>>>>

)is

Navigating

When power is applied to the control circuit, the controller screen will be active and display the Home screen, which can also be accessed by pressing the Menu Button The navigating wheel is the only navigating device necessary, although the MENU, ALARM, and BACK buttons can provide shortcuts as explained later.

Passwords

Enter passwords from the Main Menu:

• Enter Password, links to the Entry screen, which is an editable screen So pressing the

wheel goes to the edit mode where the password (5321) can be entered. The first (*) will be highlighted, rotate the wheel clockwise to the first number and set it by pressing the wheel. Repeat for the remaining three numbers.

The password will time out after 10 minutes, and is cancelled if a new password is entered or the control powers down.

• Not entering a password allows access to a limited number of parameters (with

asterisks) as shown in

Figure 13,

Figure 14,

Password Menu

Main Menu

Unit Status Off: Unit Sw ACTIVE SETPT 44.6°F

Password Entry Page

Enter Password

Enter PW ****

Figure 15

on page 60.

OM 1051-2 57

Entering an invalid password has the same effect as not entering a password.

Once a valid password has been entered, the controller allows further changes and access without requiring the user to enter a password until either the password timer expires or a different password is entered. The default value for this password timer is 10 minutes.

Navigation Mode

When the navigation wheel is turned clockwise, the cursor moves to the next line (down) on the page. When the wheel is turned counter-clockwise the cursor moves to the previous line (up) on the page. The faster the wheel is turned the faster the cursor moves. Pushing the wheel acts as an “Enter” button.

Three types of lines exist:

• Menu title, displayed in the first line as in

• Link (also called Jump) having an arrow ( >>>> ) in the right of the line and used to link

to the next menu.

• Parameters with a value or adjustable setpoint.

For example, “Time Until Restart” jumps from level 1 to level 2 and stops there.

When the Back Button is pressed the display reverts back to the previously displayed page. If the Back button is repeatedly pressed the display continues to revert one page back along the current navigation path until the “main menu” is reached.

Figure 14

When the Menu (Home) Button is pressed the display reverts to the “main page.”

When the Alarm Button is depressed, the Alarm Lists menu is displayed.

Edit Mode

The Editing Mode is entered by pressing the navigation wheel while the cursor is pointing to a line containing an editable field. Once in the edit mode pressing the wheel again causes the editable field to be highlighted. Turning the wheel clockwise while the editable field is highlighted causes the value to be increased. Turning the wheel counter-clockwise while the editable field is highlighted causes the value to be decreased. The faster the wheel is turned the faster the value is increased or decreased. Pressing the wheel again cause the new value to be saved and the keypad/display to leave the edit mode and return to the navigation mode.

A parameter with an “R” is read only; it is giving a value or description of a condition. An “R/W indicates a read and/or write opportunity; a value can be read or changed (providing the proper password has been entered).

Example 1: Check Status, for example -is the unit being controlled locally or by an external network? We are looking for the Unit Control Source Since this a unit status parameter, start at Main Menu and select View/Set Unit and press the wheel to jump to the next set of menus. There will be an arrow at the right side of the box, indicating that a jump to the next level is required. Press the wheel to execute the jump.

You will arrive at the Status/ Settings link. There is an arrow indicating that this line is a link to a further menu. Press the wheel again to jump to the next menu, Unit Status/Settings.

Rotate the wheel to scroll down to Control Source and read the result.

Example 2; Change a Setpoint, the chilled water setpoint for example. This parameter is designated as Cool LWT 1 setpoint and is a unit parameter. From the Main Menu select View/Set Unit. The arrow indicated that this is link to a further menu.

58 OM 1051-2

Press the wheel and jump to the next menu View/Set Unit and use the wheel to scroll down to Temperatures. This again has an arrow and is a link to a further menu. Press the wheel and jump to the Temperatures menu, which contains temperatures values and setpoints. The first line is Evap LWT, rotate wheel until Cool LWT 1 is highlighted. Press the wheel to enter edit mode. Rotate wheel until new setpoint is reached, then press wheel to accept the new value and exit edit mode.

Example 3; Clear an Alarm, from the Main Menu scroll down to the Alarms line. Note the arrow indicating this line is a link. Press the wheel to jump to the next menu Alarms There are two lines here; Alarm Active and Alarm Log. Alarms are cleared from the Active Alarm link. Press the wheel to jump to the next screen. With the first line highlighted, press the wheel to enter edit mode. Rotate wheel until AlmClr is set to On, then press wheel to clear the alarms.

OM 1051-2 59

Figure 15, HMI Keypad Navigation

Menu Level 1

Menu Level 2

Menu Leve l 3

Enter Pass word

Enter Password

Alarms

Scheduled Mai ntenance

Alarm Active

About This Chiller

Alarm Log

Active Alarm/W arning n

Alarm Entry 1

Starter Serial Number(s)

Starter Model Numbers

Application Version

Circuit #1

R/W

Menu Level 4

Menu Leve l 5

Cir1 Status

Visable (w/o Password)

Unit Status R Active Setpo int R En ter PW R/W Evap Leaving W ater Tem p R Unit Capacity R Unit Mode R

Next Maintenance

Next Maintenance M onth/Year R Acknowledge All R/W Service Support Reference R

About This Chiller

Model Number R G. O. Num ber R Unit Serial Num ber R

Starter Model Number(s)

Active Alarm/W arning 1 R … R

Alarm Log

… R Alarm Entry 25 R

BSP Version R

HMI GU ID R Circuit #2 R/W OBH GUID R Circuit #3 R/W

View/Set Circuit View/Set Circuit

Unit Status R

Active Setpo int R Evap Leaving W ater Tem p R

Evap Enteri ng Wa ter Temp R

Unit Mode R

Circuit #1 View/Se t Cir1 Circuit #2 Data

Circuit #3 Status /Setting s

Circuit #4 Compre ssor

Circuit Status R Circuit Mode R/W Circuit #1 Status R Circuit Capacity R Circuit #2 Status R Service Pumpdown R/W Ci rcuit #3 Status R

Circuit #4 R/W

Starter Serial Numbers

Circuit #1 R/W Circuit #2 R/W Circuit #3 R/W Circuit #4 R/W

Condenser

EXV

Configuration

Calibrate Sensors

Circuit Status

Circuit #4 Status R

60 OM 1051-2

Optional Remote User Interface

The optional remote user interface is a remote control panel that mimics operation of the controller located on the unit. Up to eight Pathfinder units can be connected to it and selected on the screen. It provides HMI (Human Machine Interface) within a building, the building engineer’s office for example, without going outdoors to the unit.

It can be ordered with the unit and shipped loose as a field installed option. It can also be ordered anytime after chiller shipment and mounted and wired on the job as explained on the following page. The remote panel is powered from the unit and no additional power supply is required.

All viewing and setpoint adjustments available on the unit controller are available on the remote panel. Navigation is identical to the unit controller as described in this manual.

The initial screen when the remote is turned on shows the units connected to it. Highlight the desired unit and press the wheel to access it. The remote will automatically show the units attached to it, no initial entry is required.

Alarm Button

w/Flashing Red

Alarm Light

Menu Button

Back Button

Push and Roll Navigating Wheel

OM 1051-2 61

62 OM 1051-2

Optional Compressor VFD

An optional variable frequency drive (VFD) for each unit compressor provides compressor speed reduction to the extent permissible by chiller load and discharge pressure requirements. The speed reduction provides significant energy savings over fixed-speed compressors.

The VFD has its own microprocessor controller that monitors VFD operation, provides safety shutdowns and sends data to the chiller controller.

VFD alarms and faults are handled the same as chiller related faults. See page 44 for information on viewing and clearing them.

Access to the VFD enclosure is by factory-trained technicians only. Unauthorized entry can

result in property damage, severe personal injury, or death.

Faults and Minor Faults/Alarms

When the drive detects a fault:

• The VFD sends a message to the chiller controller regarding the fault

• The chiller controller displays a hexadecimal number code that identifies the specific VFD fault.

Table 8 lists the fault codes.

• An alarm bell icon  will be displayed in the upper right-hand corner of all controller screens

including the optional remote user interface panel’s screens.

• The remote alarm circuit will be energized (wiring to a remote alarm device is optional)

• The drive output is interrupted and the compressor coasts to a stop.

• The drive is inoperable until the fault is corrected.

When the drive detects an alarm or minor fault:

WARNING

• No message is sent to the chiller controller since no operator action is required.

• The drive continues running the compressor.

Clearing VFD Faults

VFD faults are cleared in the same manor as any chiller unit fault. See page 44 for instructions.

Navigating VFD Fault Codes

When a VFD fault condition is detected, the VFD hexadecimal fault code will appear on the chiller controller display (HMI) as a hexadecimal code, for example; 0002H. The faults that can be corrected by the operator without accessing the VFD interior are listed in Table 8. Note the fault code and contact McQuay Service if unsuccessful in clearing the listed faults or for assistance with unlisted faults.

Table 8, Fault Code, Causes and Possible Solutions

Hexa-

decimal

Code

0083H CPF02

0095H

0097 CPF22

0019H dEv

VFD HMI

Display

CPF20,

CPF21

Fault Name,

Cause

A/D Conversion

Error

Control Circuit

Error

Hybrid IC

Error

Speed

Deviation

Table continued next page.

Possible Solutions

Cycle power to drive (Note 1)

Reduce compressor load

OM 1051-2 63

Hexa-

decimal

Code

001FH Err

0007H oC Overcurrent

0106H to

0107H

0111H,

0112H

0131H to

0139H

0205H to

0211H

0212H to

0217H

0231H to

0239H,

023AH to

023EH

0305H,

0306H

0009H oH

000AH oH1

000BH oL1

000CH oL2

0008H ov

000FH rr

0002H Uv1

0003F Uv2

0004H Uv3

VFD HMI

Display

oFA03 to

oFA06

oFA10,

oFA11

oFA30 to

oFA43

oFb03 to

oFb11

oFb12 to

oFb17

oFb30 to

oFb43

oFC05,

oFC06

Fault Name, Possible Solutions

EEPROM Write

Error

Option Card Error

Heatsink

Overheat

Heatsink

Overheat

Motor

Overload

Drive

Overload

Overvoltage

DC Bus

Braking Transistor

Failed

DC Bus

Undervoltage

Control Power

Fault

Bypass Circuit

Undervoltage

Measure the current going to the compressor

Determine if there is a sudden fluctuation in current

Verify ambient temperature within specification

Remove any adjacent heat producing equipment

Verify ambient temperature within specification

Remove any adjacent heat producing equipment

Check for power supply phase loss/fluctuation

Cycle power to drive (Note 1)

Reduce load

Cycle power to drive (Note 1)

Decrease load

Reduce load

Check motor current against nameplate

Reduce load

Check motor wiring for ground faults

Check input voltage

Cycle power to drive (Note 1)

Check for loose power connections

Check supply voltage

Cycle power to drive (Note 1)

Note

1. Depending on the fault type, the fault will shut down the circuit or entire unit.

If a circuit is still running and on its own disconnect, it can be left running. Disconnect and then reconnect the faulted circuit.

If a circuit is still running and there is a common disconnect for the unit, pump down the running circuit, disconnect and reconnect the entire unit.

VFD Changes from Non-VFD

Table 9, Setpoint Changes

Setpoint VFD Units Non-VFD Units

Light Load Stage Down Default 35 Default 40 Stop Delta T Default 1.5 Default 0.7 Stage Up Delta T Default 0.5 Default 1.0 PVM Config Default None Default Single Point Slide Position Sensor Default No Default Yes

64 OM 1051-2

Table 10, Logic Changes

Logic VFD Units Non-VFD Units

Requirements for staging a circuit on are different

Method for generating load/unload commands is different.

Pressure control target is different

Limits of SSH target are different

Triggers for transition from pressure control to SSH control are different. Triggers for transition from SSH control to pressure control are different.

If a calculated limit for pulldown rate

is exceeded when LWT error is less

than 10°C, no additional circuit can

start.

A scaled limit on pulldown rate is

used in combination with a scaled

time delay between capacity

changes based on LWT error.

Always controls to 350 kPa other

than after transition from SSH

control

SSH target varies from 3.4 to 7.0 °C

(as DSH varies from 18 to 12 °C)

Circuit running for 3 minutes and

DSH >= 12 deg C for 1 minute or

SSH < SSH target plus 1 degree C.

Evap Pressure > 350 kPa for 60

seconds

Has the logic outlined in original SRS,

without the additional logic shown at

left for VFD chillers.

An error accumulator using LWT error

and loop pulldown rate are used. Time

between capacity changes is determined by accumulator reaching limit and the time delays in individual

circuits.

Allows pressure target to vary in order

to maintain DSH (12 to 22 °C)

SSH target varies from 2.8 to 5.5 °C

(as DSH varies from 17 to 12 °C)

Low Pressure Unload not active and

LWT <= 15.5°c and SSH >= SSH

target and DSH >= 12°C for at least 3

minutes

LWT > 17°C or DSH < 12°C

Control Panel

The control panel for VFD units is different from non-VFD units due to the space requirements of the drive. See Figure 16 and Figure 17 for component layout.

OM 1051-2 65

Figure 16, Upper Section of the VFD Control Panel Section

Circuit #1

Optional

Fan VFD

Fan Contactors & Overloads Circuit #1

Optional

Fan VFD

Circuit #2

Figure 17, Lower Section of the VF Control Panel Section

D Net

Module

AC Module

Fan Contactors & Overloads Circuit #2

Unit & Circuit Switches

Main unit controller

Circuit

Control

Controller #1

Circuit

EEV #1

Controller #2

EEV #2 Control

Control

Compressor

Transformer

Thermistor

Boards 1 & 2

66 OM 1051-2

Optional Power Factor Correction Capacitors

the panel

Optional power factor correction capacitors (PFCC) located in an electrical panel may have been ordered with the chiller. If so, there is one panel per compressor and they are mounted on the side base rail near the evaporator.

The panel has no moving parts and no routine maintenance is required. There is a fuse for each phase, each with a blown fuse indicator and associated red indicating light.

A fuse failure will cause a phase fault and the unit will experience a rapid shutdown from the Phase-Voltage Monitor for wye-delta starters or internally within solid state starters. Units with compressor VFDs will not normally have PFCCs.

Before replacing the fuse, the cause for failure must be determined and corrected. The chiller will not run with a blown circuit fuse.

WARNING

Disconnect power from the unit before opening the capacitor panel. After disconnecting, allow ten

minutes for capacitor to discharge and check for no capacitor voltage with a voltmeter before

attempting any service work.

Failure to do so can result in property damage, severe personal injury, or death.

Blown fuse

indicators

Fuses, one

per phase

Power block

Red blown fuse indicator lights, one per fuse, located on top of

Capacitor, some units may have two

OM 1051-2 67

Start-up and Shutdown

McQuay service personnel or factory authorized service agency

must perform initial start-up in order to activate warranty.

Most relays and terminals in the unit control center are powered when S1 is closed and the control circuit disconnect is on. Therefore, do not close S1 until ready for start-up or the unit may start unintentionally and possibly cause equipment damage.

Seasonal Start-up

1. Double check that the discharge shutoff valve and the optional compressor suction

butterfly valves are open.

2. Check that the manual liquid-line shutoff valves at the outlet of the subcooler coils

and the oil separator oil return line shutoff valves are open.

3. Check the leaving chilled water temperature setpoint on the MicroTech III controller

to be sure it is set at the desired chilled water temperature.

4. Start the auxiliary equipment for the installation by turning on the time clock, and/or

remote on/off switch, and chilled water pump.

NOTICE

CAUTION

5. Check to see that pumpdown switches Q1 and Q2 (and Q3) are in the "Pumpdown

and Stop" (open) position. Throw the S1 switch to the "auto" position.

6. Under the "Control Mode" menu of the keypad, place the unit into the automatic cool

mode.

7. Start the system by moving pumpdown switch Q1 to the "auto" position.

8. Repeat step 7 for Q2 (and Q3).

Temporary Shutdown

Move pumpdown switches Q1 and Q2 to the "Pumpdown and Stop" position. After the compressors have pumped down, turn off the chilled water pump.

CAUTION

Do not turn the unit off using the "Override Stop" switch, without first moving Q1 and Q2 (and Q3) to the "Stop" position, unless it is an emergency, as this will prevent the unit from going through a proper shutdown/pumpdown sequence, resulting in possible equipment damage.

68 OM 1051-2

CAUTION

The unit has a one-time pumpdown operation. When Q1 and Q2 are in the "Pumpdown and Stop" position the unit will pump down once and not run again until the Q1 and Q2 switches are moved to the auto position. If Q1 and Q2 are in the auto position and the load has been satisfied, the unit will go into one-time pumpdown and will remain off until the MicroTech III control senses a call for cooling and starts the unit.

CAUTION

Water flow to the unit must not be interrupted before the compressors pump down to avoid freeze-up in the evaporator. Interruption will cause equipment damage.

CAUTION

If all power to the unit is turned off, the compressor heaters will become inoperable. Once power is resumed to the unit, the compressor and oil separator heaters must be energized a minimum of 12 hours before attempting to start the unit.

Failure to do so can damage the compressors due to excessive accumulation of liquid in the compressor.

Start-up After Temporary Shutdown

1. Insure that the compressor and oil separator heaters have been energized for at least

12 hours prior to starting the unit.

2. Start the chilled water pump.

3. With System switch Q0 in the "on" position, move pumpdown switches Q1 and Q2 to

the "auto" position.

4. Observe the unit operation until the system has stabilized.

Extended (Seasonal) Shutdown

1. Move the Q1 and Q2 (and Q3) switches to the manual pumpdown position.

2. After the compressors have pumped down, turn off the chilled water pump.

3. Turn off all power to the unit and to the chilled water pump.

4. If fluid is left in the evaporator, confirm that the evaporator heaters are operational.

5. Move the emergency stop switch S1 to the "off" position.

6. Close the compressor discharge valve and the optional compressor suction valve (if

so equipped) as well as the liquid line shutoff valves.

7. Tag all opened compressor disconnect switches to warn against start-up before

opening the compressor suction valve and liquid line shutoff valves.

8. If glycol is not used in the system, drain all water from the unit evaporator and chilled

water piping if the unit is to be shutdown during winter and temperatures below -20°F can be expected. The evaporator is equipped with heaters to help protect it down to 20°F. Chilled water piping must be protected with field-installed protection. Do not leave the vessels or piping open to the atmosphere over the shutdown period.

9. Do not apply power to the evaporator heaters if the system is drained of fluids as this

can cause the heaters to burn out.

OM 1051-2 69

Start-up After Extended (Seasonal) Shutdown

1. With all electrical disconnects locked and tagged out, check all screw or lug-type

electrical connections to be sure they are tight for good electrical contact.

DANGER

LOCK AND TAG OUT ALL POWER SOURCES WHEN CHECKING CONNECTIONS. ELECTRICAL SHOCK WILL CAUSE SEVERE PERSONAL INJURY OR DEATH.

2. Check the voltage of the unit power supply and see that it is within the ±10%

tolerance that is allowed. Voltage unbalance between phases must be within ±3%.

3. See that all auxiliary control equipment is operative and that an adequate cooling load

is available for start-up.

4. Check all compressor flange connections for tightness to avoid refrigerant loss.

Always replace valve seal caps.

5. Make sure system switch Q0 is in the "Stop" position and pumpdown switches Q1

and Q2 are set to "Pumpdown and Stop", throw the main power and control disconnect switches to "on." This will energize the crankcase heaters. Wait a minimum of 12 hours before starting up unit. Turn compressor circuit breakers to "off" position until ready to start unit.

6. Open the optional compressor suction butterfly as well as the liquid line shutoff

valves, compressor discharge valves.

7. Vent the air from the evaporator water side as well as from the system piping. Open

all water flow valves and start the chilled water pump. Check all piping for leaks and recheck for air in the system. Verify the correct flow rate by taking the pressure drop across the evaporator and checking the pressure drop curves in the installation manual, IM 997.

8. The following table gives glycol concentrations required for freeze protection.

Table 11, Freeze Protection

Temperature

°°°°F (°°°°C)

20 (6.7) 16 18 11 12

10 (-12.2) 25 29 17 20

0 (-17.8) 33 36 22 24

-10 (-23.3) 39 42 26 28

-20 (-28.9) 44 46 30 30

-30 (-34.4) 48 50 30 33

-40 (-40.0) 52 54 30 35

-50 (-45.6) 56 57 30 35

-60 (-51.1) 60 60 30 35

Notes:

1. These figures are examples only and cannot be appropriate to every situation. Generally, for an extended margin of protection, select a temperature at least 10°F lower than the expected lowest ambient temperature. Inhibitor levels should be adjusted for solutions less than 25% glycol.

2. Glycol of less than 25% concentration is not recommended because of the potential for bacterial growth and loss of heat transfer efficiency.

Ethylene Glycol Propylene Glycol Ethylene Glycol Propylene Glycol

Percent Volume Glycol Concentration Required

For Freeze Protection For Burst Protection

70 OM 1051-2

Field Wiring Diagram

Figure 18, Typical Field Wiring Diagram, Sheet 1

OM 1051-2 71

Figure 18, Typical Field Wiring Diagram, Sheet 12

NOTE: 1 The compressor alarms will not be energized by a unit fault, only the unit alarm will do so. Using the unit alarm and the

circuit alarms will include all faults and also designate which compressor has an alarm. 2 Field wiring for optional BAS continued on next page. 3 The BAS interface modules and the remote display shown above are available as options.

72 OM 1051-2

System Maintenance

General

On initial start-up and periodically during operation, it will be necessary to perform certain routine service checks. Among these are checking the liquid line sight glasses, and the compressor oil level sight glass. In addition, check the MicroTech III controller temperature and pressure readings with gauges and thermometers to see that the unit has normal condensing and suction pressure and superheat and subcooling readings. A recommended maintenance schedule is located at the end of this section.

A Periodic Maintenance Log is located at the end of this manual. It is suggested that the log be copied and a report be completed on a regular basis. The log will serve as a useful tool for a service technician in the event service is required.

Initial start-up date, vibration readings, compressor megger readings and oil analysis information should be kept for reference base-line data.

Compressor Maintenance

The semi-hermetic compressor requires no yearly scheduled maintenance. Compressor vibration is an indicator of a possible problem requiring maintenance. It is recommended that the compressor be checked with a vibration analyzer at, or shortly after, start-up and again on an annual basis. The load should be maintained as closely as possible to the load of the original test. The initial vibration analyzer test provides a benchmark of the compressor, and when performed routinely, can give a warning of impending problems.

Lubrication

No routine lubrication is required on Pathfinder units. The fan motor bearings are permanently lubricated. No further lubrication is required. Excessive fan motor bearing noise is an indication of a potential bearing failure.

Compressor oil must be ICI RL68HB, McQuay Part Number 735030446 in a 1-gallon container. This is synthetic polyolester oil with anti-wear additives and is highly hygroscopic. Care must be taken to minimize exposure of the oil to air when charging oil into the system.

The oil charge is 6 gallons (23 liters) for all compressor sizes.

Oil Filter Removal and Renewal

Fitting a New Oil Filter Element – Dismantling

Prior to this procedure, pump out the compressor; isolate the electrical supply to the control panels and compressor motor terminal.

WARNING

After the compressor has been pumped down and isolated, the oil contained inside the filter housing will remain hot enough to cause burns for some time afterwards. Always allow sufficient time for the oil to cool down so that it is cool enough not to be a danger when drained off (less than 35 °C is recommended). Severe injury from burns can result.

OM 1051-2 73

Spigot

Sealing

1 Oil Filter - 250mm

2 Oil Filter Housing Cover

3 O-Ring – 89.5x3

4 O-Ring – 76.1x3.4

5 M8 Bolts

• Unscrew and remove two hex head side cover bolts 180° apart. Insert M8 guide studs into the

vacant holes.

• Remove remaining bolts, remove oil filter housing cover.

• Pull the oil filter off of the spigot and withdraw the oil filter from the housing and clean.

• Clean oil filter housing cover plate.

Fitting a New Oil Filter Element – Reassembly

Before assembly commences, remove any paint from joint faces. Inspect parts individually for damage, ensure they are completely clean before laying them out on a sheet of clean paper in a logical order ready for reassembly.

Use fresh refrigerant oil to lubricate parts during reassembly. New O-rings must be used.

• Insert new oil filter into the housing, ensuring the filter sits tightly on the sealing spigot.

• Replace the oil filter housing cover

Filter housing cover plate – 6xM8 Bolts Removal of the filter housing cover

74 OM 1051-2

Remove filter and clean oil filter housing. Clean all other components. Replace the o-rings.

Electrical Terminals

DANGER

Electric equipment can cause electric shock which will cause severe personal injury or death. Turn off, lock out and tag all power before continuing with following service. Panels can have more than one power source.

CAUTION

Periodically check electrical terminals for tightness and tighten as required. Always use a back-up wrench when tightening electrical terminals.

Condensers

The condensers are air-cooled and constructed of 3/8" (9.5mm) OD internally finned copper tubes bonded in a staggered pattern into louvered aluminum fins. No maintenance is ordinarily required except the routine removal of dirt and debris from the outside surface of the fins. McQuay recommends the use of non-caustic, non-acidic, foaming coil cleaners available at most air conditioning supply outlets. Flush the coil from the inside out.

WARNING

Use caution when applying coil cleaners. They can contain potentially harmful chemicals. Wear breathing apparatus and protective clothing. Carefully follow the cleaner manufacturer’s MSDS sheets. Thoroughly rinse all surfaces to remove any cleaner residue. Do not damage the fins during cleaning.

If the service technician has reason to believe that the refrigerant circuit contains noncondensables, recovery of the noncondensables will be required, strictly following Clean Air Act regulations governing refrigerant discharge to the atmosphere. The service Schrader valves are located on both vertical coil headers on both sides of the unit at the control box end of the coil. Access panels are located at the end of the condenser coil directly behind the control panel. Recover the noncondensables with the unit off, after shutdown of 15 minutes or longer, to allow air to collect at the top of the coil. Restart and run the unit for a brief period. If necessary, shut the unit off and repeat the procedure. Follow accepted environmentally sound practices when removing refrigerant from the unit.

OM 1051-2 75

Optional Compressor VFD

Inspection Area Inspection Points Corrective Action

General

Conductors and Wiring

Terminals

Relays and Contactors

Inspect equipment for discoloration from overheating or deterioration.

Inspect for dirt, foreign particles, or dust collection on components

Inspect wiring and connections for discoloration, damage or heat stress.

Inspect terminals for loose, stripped, or damaged connections

Inspect contactors and relay for excessive noise during operation

Inspect coils for signs of overheating such as melted or cracked insulation.

Replace damaged equipment as required.

Inspect door seal if so equipped. Use dry air to clear foreign matter

Repair or replace damaged wire.

Tighten loose screws and replace damaged screws or terminals.

Check coil voltage for over or under voltage condition.

Replace damaged removable relays, contactors or circuit board.

Liquid Line Sight Glass

Observe the refrigerant sight glasses (one per circuit) weekly. A clear glass of liquid indicates that there is adequate refrigerant charge in the system to provide proper feed through the expansion valve.

Bubbling refrigerant in the liquid line sight glass, during stable run conditions, may indicate that there can be an electronic expansion valve (EXV) problem since the EXV regulates liquid subcooling. Refrigerant gas flashing in the sight glass could also indicate an excessive pressure drop in the liquid line, possibly due to a clogged filter-drier or a restriction elsewhere in the liquid line.

An element inside the sight glass indicates the moisture condition corresponding to a given element color. If the sight glass does not indicate a dry condition after about 12 hours of operation, the circuit should be pumped down and the filter-drier changed. An oil acid test is also recommended.

Do not use the sight glass on the EXV body for refrigerant charging. Its purpose is to view the position of the valve.

Lead-Lag

A feature on all Daikin McQuay Pathfinder air-cooled chillers is a system for alternating the sequence in which the compressors start to balance the number of starts and run hours. Lead-Lag of the refrigerant circuits is accomplished automatically through the MicroTech III controller. When in the auto mode, the circuit with the fewest number of starts will be started first. If all circuits are operating and a stage down in the number of operating compressors is required, the circuit with the most operating hours will cycle off first. The operator can override the MicroTech III controller, and manually select the lead circuit as circuit #1, #2 or #3.

76 OM 1051-2

Preventative Maintenance Schedule

PREVENTATIVE MAINTENANCE SCHEDULE

OPERATION WEEKLY

General

Complete unit log and review (Note 3) X Inspect unit for loose or damaged components and visible leaks X Inspect thermal insulation for integrity X Clean and paint as required X

Electrical ( * including the optional VFD)

Sequence test controls * X Check contactors for pitting, replace as required * X Check terminals for tightness, tighten as necessary * X Clean control panel interior * X Clean control box fan filter (Note 7 ) * X Visually inspect components for signs of overheating * X Verify compressor and oil heater operation X Megger compressor motor X

Refrigeration/Lubricant

Leak test X Check liquid line sight glasses for clear flow X Check compressor oil sight glass for correct level (lubricant charge) X Check filter-drier pressure drop (see manual for spec) X Check lubricant filter pressure drop (Note 6) X Perform compressor vibration test X Perform oil analysis test on compressor oil X

Condenser (air-cooled)

Clean condenser coils (Note 4) X Check fan blades for tightness on shaft (Note 5) X Check fans for loose rivets and cracks, check motor brackets X Check coil fins for damage and straighten as necessary X

MONTHLY

(Note 1)

Notes:

1. Monthly operations include all weekly operations.

2. Annual (or spring start-up) operations include all weekly and monthly operations.

3. Log readings can be taken daily for a higher level of unit observation.

4. Coil cleaning can be required more frequently in areas with a high level of airborne particles.

5. Be sure fan motors are electrically locked out.

6. Replace the filter if pressure drop exceeds 20 psi.

7. The weekly fan filter cleaning schedule can be modified to meet job conditions. It is important that the

filter allows full air flow.

ANNUAL

(Note 2)

OM 1051-2 77

Appendix

Definitions

Active Setpoint

The active setpoint is the setting in effect at any given moment. This variation occurs on setpoints that can be altered during normal operation. Resetting the chilled water leaving temperature setpoint by one of several methods, such as return water temperature, is an example.

Active Capacity Limit

The active setpoint is the setting in effect at any given moment. Any one of several external inputs can limit a compressor’s capacity below its maximum value.

Condenser Saturated Temperature Target

The saturated condenser temperature target is calculated by first using the following equation:

Sat condenser temp target raw = 0.833(evaporator sat temp) + 68.34

The “raw” value is the initial calculated value. This value is then limited to a range defined by the Condenser Saturated Temperature Target minimum and maximum setpoints. These setpoints simply cut off the value to a working range, and this range can be limited to a single value if the two setpoints are set to the same value.

Dead Band

The dead band is a range of values surrounding a setpoint such that a change in the variable occurring within the dead band range causes no action from the controller. For example, if a temperature setpoint is 44°F and it has a dead band of ± 2 degrees F, nothing will happen until the measured temperature is less than 42°F or more than 46°F.

DIN

Digital input, usually followed by a number designating the number of the input.

Error

In the context of this manual, “Error” is the difference between the actual value of a variable and the target setting or setpoint.

Evaporator Approach

The evaporator approach is calculated for each circuit. The equation is as follows:

Evaporator Approach = LWT – Evaporator Saturated Temperature

See page 38 for more details

Evap Recirc Timer

A timing function, with a 30-second default, that holds off any reading of chilled water for the duration of the timing setting. This delay allows the chilled water sensors (especially water temperatures) to take a more accurate reading of the chilled water system conditions.

EXV

Electronic expansion valve, used to control the flow of refrigerant to the evaporator, controlled by the circuit microprocessor.

High Saturated Condenser – Hold Value

High Cond Hold Value = Max Saturated Condenser Value – 5 degrees F

78 OM 1051-2

This function prevents the compressor from loading whenever the pressure approaches within 5 degrees of the maximum discharge pressure. The purpose is to keep the compressor online during periods of possibly temporary elevated pressures.

High Saturated Condenser – Unload Value

High Cond Unload Value = Max Saturated Condenser Value – 3 degrees F

This function unloads the compressor whenever the pressure approaches within 3 degrees of the maximum discharge pressure. The purpose is to keep the compressor online during periods of possibly temporary elevated pressures.

Light Load Stg Dn Point

The percent load point at which one of two operating compressors will shut off, transferring the unit load to the remaining compressor.

Load Limit

An external signal from the keypad, the BAS or a 4-20 ma signal that limits the compressor loading to a designated percent of full load. Frequently used to limit unit power input.

Load Balance

Load balance is a technique that equally distributes the total unit load among the running compressors on a unit or group of units.

Low Ambient Lockout

Prevents the unit from operating (or starting) at ambient temperatures below the setpoint.

Low Pressure Unload Setpoint

The psi evaporator pressure setting at which the controller will unload the compressor until a preset pressure is reached.

Low Pressure Hold Setpoint

The psi evaporator pressure setting at which the controller will not allow further compressor loading.

Low/High Superheat Error

The difference between actual evaporator superheat and the superheat target.

LWT

Leaving water temperature. The “water” is any fluid used in the chiller circuit.

LWT Error

Error in the controller context is the difference between the value of a variable and the setpoint. For example, if the LWT setpoint is 44°F and the actual temperature of the water at a given moment is 46°F, the LWT error is +2 degrees.

LWT Slope

The LWT slope is an indication of the trend of the water temperature. It is calculated by taking readings of the temperature every few seconds and subtracting them from the previous value, over a rolling one minute interval.

Milli-second

Maximum Saturated Condenser Temperature

The maximum saturated condenser temperature allowed is calculated based on the compressor operational envelope.

OM 1051-2 79

OAT

Outside ambient air temperature

Offset

Offset is the difference between the actual value of a variable (such as temperature or pressure) and the reading shown on the microprocessor as a result of the sensor signal.

pLAN

Peco Local Area Network is the proprietary name of the network connecting the control elements.

Refrigerant Saturated Temperature

Refrigerant saturated temperature is calculated from the pressure sensor readings for each circuit. The pressure is fitted to an R-134a temperature/pressure curve to determine the saturated temperature.

Soft Load

Soft Loading is a configurable function used to ramp up the unit capacity over a given time period, usually used to influence building electrical demand by gradually loading the unit.

Setpoint

SSS

Solid state starter as used on McQuay screw compressors.

Suction Superheat

Suction superheat is calculated for each circuit using the following equation:

Suction Superheat = Suction Temperature – Evaporator Saturated Temperature

See page 38 for details.

Stage Up/Down Accumulator

The accumulator can be thought of as a bank storing occurrences that indicate the need for an additional fan.

Stageup/Stagedown Delta-T

Staging is the act of starting or stopping a compressor or fan when another is still operating. Startup and Stop is the act of starting the first compressor or fan and stopping the last compressor or fan. The Delta-T is the “dead band” on either side of the setpoint in which no action is taken.

Stage Up Delay

The time delay from the start of the first compressor to the start of the second.

Startup Delta-T

Number of degrees above the LWT setpoint required to start the first compressor.

Stop Delta-T

Number of degrees below the LWT setpoint required for the last compressor to stop.

VDC

Volts, Direct current, sometimes noted as vdc.

80 OM 1051-2

McQuay Training and Development

Now that you have made an investment in modern, efficient McQuay equipment, its care should be a high priority. For training information on all McQuay HVAC products, please visit us at www.mcquay.com and click on Training, or call 540-248-9646 and ask for the Training Department.

Warranty

All McQuay equipment is sold pursuant to McQuay’s Standard Terms and Conditions of Sale and Limited Product Warranty. Consult your local McQuay Representative for warranty details. Refer to form 933-430285Y. To find your local representative, go to www.mcquay.com.

This document contains the most current product information as of this printing. For the most up-todate product information, please go to www.mcquay.com.

(800) 432-1342 • www.mcquay.com OM 1051-2 (09/10)

McQuay AWS 150A Installation Manual

Specifications and Main Features

Frequently Asked Questions

User Manual