McQuay WMC 150 Installation Manual

Operating Manual

OM WMC

WMC Magnetic Bearing Compressor Chillers

Model WMC 150 50/60 Hertz OITS Software Version 1.05.02 Control Software Version WCFU3UU03K

Group: Chiller Part Number: 330599802 Effective: December 2004

Supersedes: New

Table of Contents

Introduction............................................. 3

Features of the Control Panel................4

Definitions................................................ 5

General Description................................ 8

Control Panel.........................................10

Use with On-Site Generators................11

Sequence of Operation ......................... 12

Multi-Chiller Setup............................... 13

Operating Limits:..............................................15

Operating the Control System............. 16

Interface Panel On/Off......................................16

Start/Stop Unit...................................................16

Change Setpoints...............................................16

Alarms...............................................................16

Component Failure............................................17

Component Description........................ 17

Operator Interface Touch Screen.......................17

Unit/Compressor Controller Description..........17

Navigating.........................................................18

Unit Controller......................................21

Unit Controller Setpoints..................................21

Faults, Problems, Warnings...............................23

Unit Controller Functions................................. 24

Compressor Controller......................... 25

Compressor Controller Setpoints..................... 26

Compressor Faults, Problems, Warnings .......... 27

Compressor Controller Functions..................... 28

Compressor On-Board

Controllers............................................. 32

Interface Touch Screen......................... 34

Navigation........................................................ 34

Screen Descriptions.......................................... 36

VIEW Screens.................................................. 36

SET Screens..................................................... 42

SERVICE Screen.............................................. 55

HISTORY Screens............................................56

Download Data................................................. 57

ACTIVE ALARM Screen ................................ 58

Blank/Locked-up Screen.................................. 59

Unit Controller Menu Screens............. 60

Menu Matrix..................................................... 61

Compressor Controller Menu

Screens................................................... 77

Menu Matrix..................................................... 77

BAS Interface........................................ 79

Controllers are LONMARK certified

with an opt ional

communication module.

LONWORKS

Manufactured in an ISO Certified Facility

Illustrations and information cover McQuay International products at the time of publication and we reserve the right to make changes in design and

®™ The following are trademarks or registered trademarks of their respective companies: BACnet from ASHRAE; Modbus from Gould, Inc; L

LONWORKS from Echelon Corporation; and MicroTech II from McQuay International.

2004 McQuay International

construction at anytime without notice.

ONMARK and

2 OM WMC

Introduction

This manual provides setup, operating, and troubleshooting information for McQuay WMC centrifugal chillers with the MicroTech ΙΙ™ controller. Please refer to the current version of IMM WMC for information relating to the unit itself.

Electric shock hazard. Improper handling of this equipment can cause personal injury or

equipment damage. This equipment must be properly grounded. Connections to and

service of the MicroTech II control panel must be performed only by personnel that are

Static sensitive components. A static discharge while handling electronic circuit boards

WARNING

knowledgeable in the operation of the equipment being controlled.

CAUTION

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,

may cause interference to radio communications. Operation of this equipment in a

residential area is likely to cause harmful interference in which case the user

will be required to correct the interference at the owner’s own expense.

McQuay disclaims any liability resulting from any interference or for the correction thereof.

Temperature and humidity considerations

The unit controllers are designed to operate within an ambient temperature range of 20°F to +120°F (-7°C to +49°C) with a maximum relative humidity of 95% (non-condensing).

OM WMC 3

Features of the Control Panel

• Control of leaving chilled water within a ±0.5°F (±0.3°C) tolerance.

• Display of the following temperatures and pressures on a 10 Super VGA operator interface

touchscreen (depending on date of manufacture):

• Entering and leaving chilled water temperature

• Enter and leaving condenser water temperature

• Saturated evaporator refrigerant temperature and pressure

• Saturated condenser temperature and pressure

• Suction line, liquid line and discharge line temperatures, calculated superheat for discharge

and suction lines, and calculated subcooling for liquid line

• Automatic control of primary and standby chilled and condenser water pumps.

• Control of up to 4 stages of cooling tower fans plus modulating bypass valve and/or tower fan

VFD. Although fan staging is available, continuous, modulated control of tower capacity is preferred and recommended.

• History trend feature that will constantly log chiller functions and setpoints. The controller will store and display specific data for recall in a graphic format on the screen. Data can be downloaded for archival purposes.

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

• Plain language warning and fault diagnostics to inform operators of most warning or fault conditions. Warnings, problems and faults are time and date stamped for identification of when the fault condition occurred. In addition, the operating conditions that existed just prior to shutdown can be recalled to aid in resolving the cause of the problem.

• Twenty-five previous faults and related operating conditions are available from the display. Data can be exported for archival purposes via a 3.5-inch floppy drive or other device (depending on date of manuafacture).

• Soft loading feature reduces electrical consumption and peak demand charges during system loop pulldown.

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

• Manual control mode allows the service technician to command the unit to different operating

states. Useful for system checkout.

• BAS communication capability via L most BAS manufacturers.

• Service Test mode for troubleshooting controller outputs.

• Pressure transducers for direct reading of system pressures.

• Preemptive control of low evaporator and high discharge pressure conditions to take corrective

action prior to a fault trip.

ONTALK®, Modbus® or BACnet® standard protocols for

4 OM WMC

Definitions

Active Setpoint

The active setpoint is the parameter setting in effect at any given moment. This variation can occur 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 capacity 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.

Active-Amp-Limit

Active amp limit is the actual amp limit imposed by an outside signal such as the load limit function.

Condenser Recirc (Recirculation) Timer

A timing function, with a 30-second default, that holds off any reading of condenser water for the duration of the timing setting. This delay allows the sensors to take a more accurate reading of the condenser water temperature.

Dead Band

The dead band is a set of values associated with a setpoint such that a change in the variable occurring within the dead band causes no action from the controller. For example, if a temperature setpoint is 44°F and it has a dead band of ± 2.0 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.

Discharge Superheat

Discharge superheat is calculated using the following equation: Discharge Superheat = Discharge Temperature – Condenser Saturated Temperature

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

Evap Hold-loading

This is a setpoint that establishes the minimum evaporator pressure to which the chiller is allowed to go. It signals that the unit is at full load so the no further loading will occur that would lower the pressure even further.

Evap Recirc (Evaporation Recirculation) 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 to take a more accurate reading of the chilled water temperature.

OM WMC 5

EXV

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

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. Used to limit unit power input.

Load Balance

Load balance is a technique that equally distributes the total unit load between two or more running compressors.

Low Pressure Hold (Inhibit) Setpoint

The psi evaporator pressure setting at which the controller will not allow further compressor loading. “Hold” and “Inhibit” are used interchangeably.

Low Pressure Unload Setpoint

The psi evaporator pressure setting at which the controller will unload the compressor in an effort to maintain the minimum setting.

LWT

Evaporator 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 chilled 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.

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.

OITS

Operator Interface Touch Screen, one screen per unit provides operating data visually and accommodates setpoint entry.

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. The pressure is fitted to an R-134a temperature/pressure curve to determine the saturated temperature.

6 OM WMC

Soft Load

Soft Load is a control sub-routine that allows the chiller to load up gradually. It requires setpoint inputs of selecting it by Yes or No inputs, by selecting the percent load to start ramping up, and by selecting the time to ramp up to full load (up to 60 minutes).

Setpoint

Suction Superheat

Suction superheat is calculated for each circuit using the following equation: Suction Superheat = Suction Temperature – Evaporator Saturated Temperature

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 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.

VFD

Variable Frequency Drive, a device located on the compressor, used to vary the compressor speed.

OM WMC 7

General Description

Figure 1, Major Component Location

NOTE: Some prototype units may have the OITS and control panel on the opposite side.

Unit Control Panel

Evaporator Relief

Valve

Operator Interface

Panel (OITS)

Compressor #1 with On-Board

Compressor #2 with On-Board Controls

Condenser

Relief Valves

Optional Unit Disconnect Switch

& Single Point Power Connection

Circuit #1 Power Panel

Electronic Expansion Valve

Circuit #2 Power Panel

General Description

The centrifugal MicroTech ΙΙ control system consists of microprocessor-based controllers in the control panel, as well as on-board the compressors, providing monitoring and control functions required for the controlled, efficient operation of the chiller. The system consists of the following components:

• Operator Interface Touch Screen (OITS), one per unit-provides unit information and is the primary setpoint input instrument. It has no control function.

• Unit Controller, one per chiller-controls unit functions and communicates with all other controllers. It is the secondary location for setpoint input if the OITS is inoperative. It is located in the control panel that is adjacent to the OITS Panel.

• Compressor Controller for each compressor-controls compressor functions. They are located in the control panel.

• On-board compressor controller mounted on each compressor that monitors compressor operation and controls bearing operation.

The operator can monitor all operating conditions by using the unit-mounted OITS. In addition to providing all normal operating controls, the MicroTech II control system monitors equipment protection devices on the unit and 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. Important operating conditions at the time an alarm condition occurs are retained in the controller’s memory to aid in troubleshooting and fault analysis.

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The system is password protected and only allows access by authorized personnel. The operator must enter the password into the touch screen (or one of the controller's keypad) before any setpoints can be altered.

NOTE: It is important to understand that the OITS is the operator interface device under normal conditions. If, and only if, it is unavailable, should the unit controller be used to change setpoints or operate the chiller.

Figure 2, Major Control Components

pLAN

OPERATOR

INTERFACE

TOUCH-SCREEN

UNIT

CONTROLLER

COMPRESSOR

CONTROLLER

COMPRESSOR CONTROLLER

Color Graphics

Touch-Screen Interface

View Data, Input Setpoints

OPTIONAL BAS

ON-BOARD. CONTROLLER

Stores Histor

UNIT

Analog Inputs

Analog Outputs

Digital Inputs

Digital Outputs

COMPRESSOR

Analog Inputs

Analog Outputs

Digital Inputs

Digital Outputs

COMPRESSOR

Analog Inputs

Analog Outputs

Digital Inputs

Digital Outputs

OM WMC 9

Control Panel

The unit and compressor controllers along with unit and compressor on/off switches are mounted in the unit control panel, which is mounted adjacent to the OITS panel. See Figure 1. The switches are designated “I” for on and “0” for off. The compressor on/off switch should only be used when an immediate stop is required since the normal shut down sequence is bypassed.

The switch panel also has a Circuit Breaker that interrupts power to the cooling tower fans, valves and evaporator and condenser pumps, if any of these are tied into the MicroTech II controller for control of their operation. If these components operate independently from the chiller control, the breaker has no effect.

The unit controller's primary function is processing data relating to the entire chiller unit operation as compared to data relating to the compressor operation. The unit controller processes information and sends data to the compressor controllers and devices and relays information to the OITS for graphic display. It has a 4x20 LCD display and keys for accessing data and changing setpoints. The controller LCD can display most of the same information as the OITS and can operate the chiller independently if the OITS is not available.

Figure 3, Control Panel Interior

Switch Panel and

Switches, See Below.

Unit Controller

Compressor #1

Controller

Compressor #2

Controller

Figure 4, Switch Locations

Compressor #1 Switch

Compressor #2 Switch

Unit Switch

Circuit breaker

10 OM WMC

Use with On-Site Generators

WMC chillers have their total tonnage divided between two compressors that start sequentially and they are operated with variable frequency drives. These features make WMC chillers especially appropriate for use in applications where they may be required to run with on-site electrical generators. This is particularly true when the generators are used for temporary power when the utility power is lost.

Starting/Stopping Procedure: The stopping of the chiller in the event of a power failure should be uneventful. The chiller will sense a loss of voltage and the compressors will stop, coasting down using power generated from their dynamic braking to maintain the bearing magnetic field. The stop signal will initiate a three-minute stop-to-start timer, effectively preventing compressor restart for three minutes. The timer is adjustable from three to fifteen minutes, but the recommended, and default value, is three minutes. This interval allows the generator sufficient time to get up to speed and stabilize. The chiller will restart automatically when the start-to-start timer expires.

Transfer Back to Grid Power: Proper transfer from stand-by generator power back to grid power is essential to avoid compressor damage.

Stop the chiller before transferring supply power from the generator back to the utility power grid. Transferring power while the chiller is running can cause severe compressor damage.

The necessary procedure for reconnecting power from the generator back to the utility grid is show below. These procedures are not peculiar to McQuay units only, but should be observed for any chiller manufacturer.

CAUTION

1. Set the generator to always run five minutes longer than the unit start-to-start timer, which could be set from 15 to 60 minutes. The actual setting can be viewed on the operator interface panel on the Setpoint/Timer screen.

2. Configure the transfer switch, provided with the generator, to automatically shut down the chiller before transfer is made. The automatic shut-off function can be accomplished through a BAS interface or with the “remote on/off” wiring connection shown in Figure 11. A start signal can be given anytime after the stop signal since the three-minute start-to-start timer will be in effect.

Chiller Control Power: For proper operation on standby power, the chiller control power must remain as factory-wired from a unit-mounted transformer. Do not supply chiller control power from an external power source because the chiller may not sense a loss of power and do a normal shutdown sequence.

OM WMC 11

Sequence of Operation

Start-up of WMC Compressors: “Next On” status

If none of the “OFF” conditions are true, then all the MicroTech II compressor controls in a network of up to 2 units (four compressors) will pole the status of each to determine the one having “Next On” status, which is usually the compressor with the least starts. This takes about one minute.

Evap (Evaporator) Pump Start

Once this is determined, the unit controller of the chiller with the ‘Next On’ compressor (when there are two chillers) will start the evaporator pump and determine if there is load based on the water temperature. This is determined if the leaving evaporator water is above the ‘LWT Setpoint’ plus ‘Startup Delta T’. If there is no load, based on the temperature, the unit is in the state of ‘Awaiting Load’.

Interlock On

If there is load, the unit waits for the Evaporator Recirculation Timer period (default value of 30 seconds) and starts the Interlock Timer for 10 sec.

Cond (Condenser) Pump Start

After Interlock is confirmed, the controller starts the Condenser Pump and checks for condenser flow before starting the first compressor.

Compressor Start

Starting the compressor is accomplished by setting the Demand to 25% of the MAX KW setpoint. When the actual RPM of the compressor exceeds 350 RPM, the demand setting is allowed to be governed by the normal control logic.

Compressor Run

The compressor that is running will signal all other compressors when it reaches full load. Full load status is determined when any one of the following tests is true:

1. Percent RLA exceeds 100% or the Active-Amp-Limit from an external-limiting source.

2. Evap Saturation pressure drops below the Evap Hold-Loading pressure setpoint.

3. Actual compressor RPM exceeds 97% of Max RPM limit from compressor.

Lag Compressor Staging

The ‘Next On’ compressor, will initiate the following staging sequence when it receives a Full Load indication from the Lead compressor, or all other running compressors in the case of a four compressor (two units) setup.

12 OM WMC

The lag compressor will start (Demand set to 25% of Max KW setpoint). When the actual RPM exceeds 350 RPM, the lead compressor will unload to 25% of the MAX KW setpoint. The lead compressor will maintain this demand setting for a time period set by the Step-Down timer (found in Set COMP1 SPs (8) ). When the Step–Down timer expires, both compressors should be nearly matched in capacity and can began amp balancing to share the load equally.

Note: If the “Next On” compressor is on another chiller, the controller will start that chiller ’s evaporator and condenser pumps, if they are separate from the lead unit’s pumps. Only compressors on the same unit will unload the lead compressor before starting the lag compressor.

Unloading compressors:

The setpoint of ‘Nominal Capacity’ is used for defining the point to unload a compressor on a single or two-chiller system. With each compressor having its ‘Nominal Capacity’ defined, then the network, which is load balanced, continues to unload at 0.2 tenths or more below setpoint. Each compressor keeps computing the spare capacity of the network. When the designated ‘Next Off’ sees enough spare capacity, it will turn off. Then similarly, in about 40 seconds, a new compressor will be designated as the ‘Next Off’ and the spare capacity will continue to be calculated between the remaining compressors. Compressors continue to unload and stage off until there is only one compressor running. It will shut off when the water temperature reaches the LWT Setpoint minus the Shutdown Delta T.

Multi-Chiller Setup

Component Description

Figure 5, Isolation Board, Unit Cont rol Panel

2 3

8 9

NOTE: J1 connection board is located in back of J2.

LED – S1

1 2

3 4

7 8

RELAY

LED – S2

MCQUAY MICROTECH II Contro lle r

ISOLATION BOARD

330272602

1 2

CAP

1 2 3

LED

9 8

4 3 2

The unit control panel receives power from the compressor control panels. The Isolation Board provides electrical isolation for the 24 VAC, Class 2 power supplies coming in from each compressor control panel to the J1 connector (for dual chillers only). It also isolates the pLAN communication on connectors J3 and J4 from the J6 connector, which is only used for multiple chiller connection and operation.

The Relay selects which compressor power supply (both are wired in) to use for powering the unit controller (and BACnet Module, if so equipped).

LED SI and S2 signal that power is available from compressor panel #1 or #2 respectively.

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The LED located in the lower right of the board signals that the J6 isolated board circuit has power.

The J2 connector is for the OITS power and communication. The J6 connector is for field interconnection of multiple chillers. All other wiring referred to

above is factory wired on dual compressor units.

pLAN Setup

The pLAN communication wiring and setup required for dual compressor operation is setup in the factory and should be reviewed when the chiller is initially started after installation or if there is any change made in the chiller control hardware. pLan RS485 communication wiring between chillers should be field wired before start-up and installed as a NEC Class 1 wiring system.

Figure 6, Communication Wiring

Chiller

pLAN

OITS

Isol Bd

BAS

Interface

Isolated pLAN for

Multiple Chillers

pLAN

Isol Bd

UNIT

COMP

Comp

Control

Chiller B

COMP

MODBUS

COMP

Comp

Control

COMP

MODBUS

BAS

Interface

Comp

Control

Isolated pLAN for

Multiple Chillers

Comp

Control

14 OM WMC

Table 1, Address DIP Switch Settings for Controllers Usi ng pLAN).

Chiller Comp 1 Comp 2

NOTES:

1 2 5 6 7 8

100000 010000 101000 011000 111000 000100

9 10 13 14 15 16

100100 010100 101100 011100 111100 000010

Unit

Controller

Reserved Operator Interface Reserved

1. Two WMC units can be interconnected.

2. The interface setting is not a DIP switch setting. The ‘Operator Interface Touch Screen’ (OITS) address is selected by selecting the ‘service’ set screen. Then, with the Technician level password active, select the ‘pLAN Comm’ button. Buttons A(7), B(15), C(23), D(31) will appear in the middle of the screen, then select the letter for the OITS address for the chiller that it is on. Then close the screen. Note that A is the default setting from the factory.

3. There are six Binary DIP Switches: Up is ‘On’, indicated by ‘1’. Down is ‘Off’, indicated by ‘0’. They are slide and not rocker switches. They are located on the upper-left corner of the face of the controller.

Operator Interface Touch Screen (OITS) Settings

Settings for any type of linked multiple compressor operation must be made to the MicroTech II controller. Settings are made in the factory prior to shipment, but must be verified in the field before startup. Settings for multiple chiller installations are set in the field on the Operator Interface Touch Screen as follows:

Maximum Comp resso rs ON WMCs.

Sequence and Staging Sequence sets the sequence in which compressors will start. Setting all to “1” evokes the automatic lead/lag feature and is the preferred setting.

Nominal Capacity

– SETPOINTS - MOTOR screen, Selection #14. The setting is the compressor

design tons. Compressors on dual units are always of equal capacity.

– SETPOINTS - MODES screen, Selection #9 = 2 for a WMC, 4 for 2

– SETPOINTS - MODES screen, Selection #10 & #12; #11 & #13.

pLAN Setup

1. With no pLAN connections between chillers, disconnect control power and set the DIP switches as shown in Table 1.

2. With all manual switches off, turn on control power to each chiller and set each OITS address (see Note 2 above).

3. Verify correct nodes on each OITS Service Screen.

4. Connect chillers together (pLAN, RS 485, between J6 connections on each unit’s isolation boards.

5. Verify correct nodes on each OITS Service Screen

Operating Limits:

Maximum standby ambient temperature, 130°F (55°C) Minimum operating ambient temperature (standard), 35°F (2°C) Leaving chilled water temperature, 38°F to 60°F (3°C to 15°C) Maximum operating evaporator inlet fluid temperature, 66°F (19°C) Maximum startup evaporator inlet fluid temperature, 90°F (32°C) Maximum non-operating inlet fluid temperature, 100°F (38°C) Minimum condenser water entering temperature,55°F (11.8°C) Maximum entering condenser water temperature, 105°F (40.6°C) Maximum leaving condenser water temperature, 115°F (46.1°C)

OM WMC 15

Operating the Control System

Interface Panel On/Off

The Operator Interface Panel is turned on and off with a push-push switch located at the upper-left corner of the panel. ON is the outermost switch position and a white band will be visible on the switch stem. Off is innermost and no white is visible.

The screen is equipped with a screen saver that blackens the screen. Touching the screen anywhere reactivates the screen. If the screen is black, touch it first to be sure it is on before using the ON/OFF switch.

Start/Stop Unit

There are four ways to start or stop the chiller. Three are shown below and selected in SETPOINT\ MODE\SP3; the fourth way is through panel-mounted switches:

1. Operator Interface Panel (LOCAL)

Home Screen 1 has AUTO and STOP buttons that are only active when the unit is in "LOCAL CONTROL". This prevents the unit from being accidentally started or stopped when it is normally under control from a remote switch or BAS. When these buttons are pressed, the unit will cycle through its normal starting or stopping sequence.

2. Remote SWITCH

Selecting SWITCH in SP3 will put the unit under the control of a remote switch that must be wired into the control panel (see Figure 11 on page 33).

3. BAS

BAS input is field-wired into a module that is factory-installed on the unit controller.

Control Panel Switches

The unit control panel, located adjacent to the Interface Panel, has switches inside the panel for stopping the entire unit or individual compressors. When the UNIT switch is placed in the OFF position the chiller will shut down through the normal shutdown sequence, whether one or two compressors are on.

The COMPRESSOR switches will immediately shut down the compressor without going through the shutdown sequence when placed in the OFF position. It is equivalent to an emergency stop switch.

Change Setpoints

Setpoints are easily changed on the Operator Interface Touch Screen (OITS). A complete description of the procedure begins on page 43. Setpoints can also be changed in the unit controller, but this is not recommended except in an emergency, when the OITS is unavailable.

Alarms

A red ALARM light in the lower middle of any screen is illuminated if there is an alarm. If the optional remote alarm is wired in, it too will be energized.

There are three types of alarms:

• Fault, equipment protection alarms that shut a unit or compressor off.

• Problem, limit alarms that limit compressor loading in response to an out-of-normal condition.

If the condition that caused a limit alarm is corrected, the alarm light will be cleared automatically.

• Warning, notification only, no action taken by controller.

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Any type will light the ALARM light. Procedures for dealing with alarms are shown below:

1. Press the alarm light button. This will go directly to the ACTIVE ALARMS screen.

2. The alarm description (with date stamp) will be shown.

3. Press the ACKNOWLEDGE button to recognize the alarm.

4. Correct the condition causing the alarm.

5. Press the CLEAR button to clear the alarm from the controller. If the fault condition is not fixed, the alarm will continue to be on and the unit will not be able to be restarted.

Component Failure

Chiller Operation without the Operator Interface Panel

The Interface Panel communicates with the unit and compressor controllers, displaying data and transmitting touch screen inputs to the controllers. It does no actual controlling and the chiller can operate without it. Should the Touch Screen become inoperable, no commands are necessary for continuing unit operation. All normal inputs and outputs will remain functional. The unit controller can be used to view operational data, to clear alarms and to change setpoints, if necessary.

Component Description

Operator Interface Touch Screen

The operator interface touch screen (OITS) is the primary device for entering commands and entries into the control system. (Settings can also be made directly into the unit controller.) The OITS can also display controller data and information on a series of graphic screens. A single OITS is used per unit.

The OITS panel has a floppy drive, or some other devise, that can be used for down-loading information.

The OITS panel is mounted on a moveable arm to allow placement in a convenient position for the operator.

There is a screen-saver programed into the system. The screen is reactivated by touching it anywhere.

Unit/Compressor Controller Description

Hardware Structure

The controllers are fitted with a microprocessor for running the control program. There are terminals for connection to the controlled devices (for example: solenoid valves, tower fans, pumps). The program and settings are saved permanently in FLASH memory, preventing data loss in the event of power failure, without requiring a back-up battery.

Each controller connects to other controllers, the on-board compressor microprocessors and the OITS via a local communications network (pLAN). The unit controller also has remote communication capability for BAS interface.

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Keypad

A 4 line by 20 character/line liquid crystal display and 6-button keypad is mounted on the unit and compressor controllers. Its layout is shown below.

Figure 7, Controller Keypad

Red Alarm Light Behind

Key-to-Screen Pathway

Air Conditioni ng

ALARM < <

MENU Key

VIEW

SET

ARROW Keys (4)

ENTER Key with

Green Run Light

Behind

The four arrow keys (UP, DOWN, LEFT, RIGHT) have three modes of use:

• Scroll between data screens in the direction indicated by the arrows (default mode).

• Select a specific data screen in the menu matrix using dynamic labels on the right side of the

display such as ALARM, VIEW, etc (this mode is entered by pressing the MENU key). For ease of use, a pathway connects the appropriate button to its respective label on the screen.

• Change field values in setpoint programming mode according to the following table:

LEFT key = Default RIGHT key = Cancel UP key = Increase (+) DOWN key = Decrease (-) These four programming functions are indicated by one-character abbreviation on the right side of the display. This programming mode is entered by pressing the ENTER key.

Getting Started

There are two basic procedures to learn in order to utilize the MicroTech II controller:

1. Navigating through the menu matrix to reach a desired menu screen and knowing where a particular screen is located.

2. Knowing what is contained in a menu screen and how to read that information or how to change a setpoint contained in the menu screen.

Navigating

The menus are arranged in a matrix of screens across a top horizontal row. Some of these toplevel screens have sub-screens located under them. The location of each controller’s screens can be found in the following table:

Controller Screen Matrix Screen Details

Unit Page 61 Page 63 Compressor Page 77 Not Applicable

There are two ways to navigate through the menu matrix to reach a desired menu screen.

1) One is to scroll through the matrix from one screen to another using the four ARROW keys.

2) Another way is to use shortcuts to work through the matrix hierarchy. From any menu screen,

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a) Pressing the MENU key will take you to the top level of the hierarchy. The display will

show ALARM, VIEW, and SET as shown in Figure 7. One of these choices can then be selected by pressing the key connected to it via the pathway shown in the figure.

b) Depending on the top-level selected, a second level of screens will appear. For example,

selecting ALARM will go the next level of menus under ALARM (ALARM LOG or ACTIVE ALARM). Selecting VIEW will go the next level of menus (VIEW COMPRESSOR STATUS, VIEW UNIT STATUS, VIEW EVAPORATOR, or VIEW CONDENSER). Selecting SET will go to a series of menus for looking at and changing setpoints.

c) After selecting this second level, the desired screen can be acquired using the arrow keys.

A typical final screen is shown below.

Pressing the MENU key from any menu screen will automatically return you to the MENU mode.

Figure 8, Typical Menu Display and Keypad Layout

Air Condit i oning

MENU Key

VIEW UNIT STATUS Unit = COOL Compr. #1/#2=OFF/OFF Evap Pump = RUN

ARROW Keys

ENTER Key

Menu Screens

A hierarchical menu structure is used to access the various screens. Each menu screen can have one to four lines of information. Optionally, the last menu selection can access one of a set of screens that can be navigated with the UP/DOWN arrow keys (see the scrolled menu structure below). Menu selection is initiated by pressing the MENU key, which changes the display from a data screen to a menu screen. Menu selections are then made using the arrow keys according to labels on the right side of the display (the arrows are ignored). When the last menu item is selected, the display changes to the selected data screen. An example follows showing the selection of the “VIEW COMPRESSOR (n) screen. Suppose the initial screen is:

ALARM LOG

(data) (data) (data)

After pressing the MENU button, the top-level menu screen will show:

< ALARM < VIEW < SET <

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After pressing the “VIEW” menu button, a menu screen will show:

VIEW < COMPRESSOR

< UNIT < EVAPORATOR < CONDENSER

After pressing the “COMPRESSOR” menu button, the selected data screen will show:

VIEW COMP (n)

(screen n data) (screen n data) (screen n data)

Where “n” is the number of the last viewed COMPRESSOR screen. The arrow keys will automatically return to the “scroll” mode at this time. Different compressor screens can then be selected with the UP/DOWN arrow keys.

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Unit Controller

Table 2, Unit Controller, Analog Inputs

# Description Signal Source Range

1 Reset of Leaving Water Temperature 4-20 mA Current 0-(10 to 80°F)

Entering Evaporator W ater

Temperature Entering Condenser W at er

Temperature 4 Leaving Condenser Water Temperature NTC Thermistor (10k@25°C) -58 to 212°F 5 Liquid Line Refrigerant Temperature NTC Thermistor (10k@25°C) -58 to 212°F 6 Demand Limit 4-20 mA Current 0-100 %RLA 7 Evaporator Water Flow 4 to 20 mA Current 0 to 10,000 gpm 8 Condenser Water Flow 4 to 20 mA Current 0 to 10, 000 gpm 9 Refrigerant Leak Sensor 4 to 20 mA Current 0 to 100 ppm

10 Spare

Table 3, Unit Controller, Digital Inputs

# Description Signal Signal

1 Unit OFF Switch 0 VAC (Stop) 24 VAC (Auto) 2 Remote Start/Stop 0 VAC (Stop) 24 VAC (Start) 3 Not Used 4 Evaporator Water Flow Switch 0 VAC (No Flow) 24 VAC (Flow) 5 Condenser Water Flow Switch 0 VAC (No Flow) 24 VAC (Flow)

NTC Thermistor (10k@25°C) -58 to 212°F NTC Thermistor (10k@25°C) -58 to 212°F

Table 4, Unit Controller, Digital Outputs

# Description Load Output OFF Output ON

1 Evaporator Water Pump #1 Pump Contactor P ump OFF Pump ON 2 Evaporator Water Pump #2 Pump Contactor P ump OFF Pump ON 3 Condenser Water Pump #1 Pump Contactor P ump OFF Pump ON 4 Condenser Water Pump #2 Pump Contactor P ump OFF Pump ON 5 Tower Fan #1 Fan Contactor Fan OFF Fan ON 6 Tower Fan #2 Fan Contactor Fan OFF Fan ON 7 Spare 8 Alarm Alarm Indicator A l arm OFF Alarm ON 9 Tower Fan #3 Fan Contactor Fan OFF Fan ON

10 Tower Fan #4 Fan Contactor Fan OFF Fan ON

Table 5, Unit Controller, Analog Outputs

# Description Output Signal Range

1 Cooling Tower Bypass Valve Position 0 to 10 VDC 0 to 100% Open 2 Cooling Tower VFD Speed 0 to 10 VDC 0 to 100% 3 EXV signal to IB Valve Control Bd. 0 to 10 VDC 0 to 100%

Unit Controller 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.

The “Type: column defines whether the setpoint is part of a coordinated set of duplicate setpoints in different controllers. There are three possibilities as given below:

N = Normal setpoint - Not copied from, or copied to, any other controller M = Master setpoint - Setpoint is copied to all controllers in the “Sent To” column S = Slave setpoint - Setpoint is a copy of the master setpoint (in the Unit controller)

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At power-up the slave node checks if the master node is operational and if so, it sets its copy of the setpoint equal to the master’s. Otherwise, the setpoint remains unchanged. During normal operation, any time the master setpoint changes, the slave is updated as well.

The PW (password) column indicates the password that must be active in order to change the setpoint. Codes are as follows:

O = Operator, M = Manager, T = Technician (not available through the 4x20 display/keypad) The following table groups setpoints that relate to the entire unit operation and are stored, for the

most part, in the unit controller. All settings are made through the OITS, indiscriminately as to whether they are “unit” or “compressor”.

Table 6, Unit Controller Setpoints

Description Default Range Type PW

Unit

Unit Enable OFF OFF, ON M O Pg. 53 Control Source KEYPAD Display Units

Language ENGLISH ENGLISH, (TBD) N O -BAS Protocol NONE

Leaving Water

Cool LWT Startup Delta T Shutdown Delta T LWT Reset Type NONE NONE, RET URN, 4-20mA N M Pg. 24 Max Reset Delta T Start Reset Delta T

Timers

Evap Recirculate 30 sec 15 sec to 5 min N M Pg. 5

Pumps

Evap Pump Cond Pump

Cooling Tower

Tower Control None None, Temperature, Lift N M Pg. 49 Tower Stages 2 1 to 4 N M Pg. 49 Stage Up Time 2 min 1 to 60 min N M Pg. 49 Stage Down Time 5 min 1 to 60 min N M Pg. 49 Stage Differential (Tem p) Stage Differential (Lift) 6.0 psi 1.0 to 20.0 psi N M Pg. 49 Stage #1 On (Temp) Stage #2 On (Temp) Stage #3 On (Temp) Stage #4 On (Temp) Stage #1 On (Lift) 35 psi 10 to 130 ps i N M Pg. 49 Stage #2 On (Lift) 45 psi 10 to 130 ps i N M Pg. 49 Stage #3 On (Lift) 55 psi 10 to 130 ps i N M Pg. 49 Stage #4 On (Lift) 65 psi 10 to 130 ps i N M Pg. 49

Cooling Tower Valve / VFD

Valve/VFD Control None Valve Setpoint (Temp)

Valve Setpoint (Lift) 30 psi 10 to 130 psi N M Pg. 49 Valve Deadband (Temp) Valve Deadband (Lift) 4.0 psi 1.0 to 20.0 psi N M Pg. 49

°F/psi °F/psi, °C/kPa

44. 0°F 40.0 to 80.0 °F

3.0°F 0.0 to 10.0 °F

3.0°F 0.0 to 3.0 °F

0.0°F 0.0 to 20.0 °F

10. 0°F 0.0 to 20.0 °F

Pump #1

Only

Pump #1

Only

3.0 °F 1.0 to 10.0 °F

70 °F 40 to 120 °F 75 °F 40 to 120 °F 80 °F 40 to 120 °F 85 °F 40 to 120 °F

65 °F 40 to 120 °F

2.0 °F 1.0 to 10.0 °F

Pump #1 Only, Pump #2 Only, A uto Pump #1 Only, Pump #2 Only, A uto

None, Valve Setpoint, Valve S t age,

VFD Stage, Valve SP/ V F D Stage

KEYPAD, BAS,

DIGITAL INPUT

NONE, BACnet, LonWorks,

MODBUS, N2

Lead, #1 Primary, #2 Primary Lead, #1 Primary, #2 Primary

N O Pg. 53 N O --

N M Pg. 53, Pg 79

M O Pg. 11, Pg. 54 M O Pg. 11, Pg. 54 M O Pg. 11, Pg. 54

N M Pg. 24 N M Pg. 24

N M Pg. 68 N M Pg. 68

N M Pg. 49

N M Pg. 49 N M Pg. 49 N M Pg. 49 N M Pg. 49

N M Pg. 49 N M Pg. 49

N M Pg. 49

Continued on next page

Manual

Reference

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Description Default Range Type PW

Stage Down @ 20% 0 to 100% N M Pg. 49 Stage Up @ 80% 0 to 100% N M Pg. 49 Valve Control Range (Min) 10% 0 to 100% N M Pg. 49 Valve Control Range(Max) 90% 0 to 100% N M Pg. 49

Valve Type Minimum Start P osition 0% 0 to 100% N M Pg. 49

Minimum Position @ Maximum Start Posit i on 100% 0 t o 100% N M Pg. 49 Maximum Position @ Error Gain 25 10 to 99 N M Pg. 49 Slope Gain 25 10 to 99 N M Pg. 49

(To Tower)

60 °F 0 to 100 °F

90 °F 0 to 100 °F

NC, NO N M Pg. 49

N M Pg. 49

Manual

Referance

These setpoints are normally viewed or changed on the OITS.

Faults, Problems, Warnings

Faults (Equipment Protection Shutdowns)

There are no Unit protection shutdown alarms; all such alarms are handled through the compressor controllers.

Problems (Limit Alarms)

The following alarms limit operation of the chiller in some way as described in the Action Taken column.

Table 7, Unit Controller Limit Alarms

Description Occurs When: Action Taken Reset

Evaporator Pump #1 Fault

Evaporator Pump #2 Fault

Condenser Pump #1 Fault

Condenser Pump #2 Fault

Entering Evaporator Water Temperat ure Sensor Fault

No flow indicated for (5 sec) with Evaporator P ump #1 ON

AND [the other pump is avai l abl e (per the Evap Pump

SP) AND has not faulted]

No flow indicated for (5 sec) with Evaporator P ump #2 ON

AND [the other pump is avai l abl e (per the Evap Pump

SP) AND has not faulted]

No flow indicated for (5 sec) with Condenser P ump #1 ON

AND [the other pump is avai l abl e (per the Evap Pump

SP) AND has not faulted]

No flow indicated for (5 sec) with Condenser P ump #2 ON

AND [the other pump is avai l abl e (per the Evap Pump

SP) AND has not faulted]

Sensor fault AND leaving water reset i s based on entering

water

Start pump #2 Manual

Start pump #1 Manual

Start pump #2 Manual

Start pump #1 Manual

Manual.

Reset mode is

set to No Reset

(Reset mode goes back to

Entering

Water)

Warnings

The following “alarms” only generate a warning message to the operator. Chiller operation is not affected.

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Table 8, Unit Controller Warnings

Description Occurs When: Action Taken Reset

Entering Evaporator Temperature Sensor Fault Entering Condenser Temperature Sensor Fault Leaving Condenser Temperature Sensor Fault Liquid Line Refrigerant Temperature Sensor Fault

Sensor is open or shorted Annunciation Automat i c Sensor is open or shorted Annunciation Automat i c Sensor is open or shorted Annunciation Automat i c Sensor is open or shorted Annunciation Automat i c

Unit Controller Functions

Leaving Water Temperature (LWT) Reset

The Active Leaving Water variable shall be set to the current Leaving Water Temperature (LWT) setpoint unless modified by one of the reset methods below. (The current LWT setpoint is Cool LWT as determined by the chiller mode.) The type of reset in effect is determined by the LWT Reset Ty pe setpoint.

Reset Type – NONE

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

Reset Type – RETURN

The Active Leaving Water variable is adjusted by the return water temperature. When the chiller mode = COOL, the Active Leaving Water variable is reset using the following

parameters:

1. Cool LWT setpoint

2. Max Reset Delta T setpoint

3. Start Reset Delta T setpoint Reset is accomplished by changing the Active Leaving Water variable from the (Cool LWT

setpoint) to the (Cool LWT setpoint + Max Reset Delta T setpoint) when the evaporator (return – leaving) water temperature delta varies from the (Start Reset Delta T setpoint) to 0.

The Active Leaving Water variable is set equal to the Cool LWT setpoint if the reset signal is less than or equal to 4 mA. It is set equal to (Cool LWT setpoint + Max Reset Delta T setpoint) if the reset signal equals or exceeds 20 mA. The Active Leaving Water variable will vary linearly between these extremes if the reset signal is between 4 mA and 20 mA. An example of this action is shown below.

LWT Reset (Cool mode)

(temperatures are examples only)

(54.0°F)

Max Reset Delta T

(10.0°F)

Cool LWT Set-Point

(44.0°F)

0 ma

4 ma

20 ma

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