McQuay WMC 145S Installation Manual
Operating Manual
OM WMC-3
Group: Chiller
Part Number: 331374701
Effective: August 2007
Supersedes: OM WMC-2
WMC Magnetic Bearing Compressor Chillers
Model WMC 145S – 290D,
50/60 Hertz
Model WMM 145S, 60 Hertz
OITS Software Version: 2.01.01
Control Software Version: WMCU3UU02B
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:..............................................14
Operating the Control System..............15
Interface Panel On/Off......................................15
Start/Stop Unit..................................................15
Change Setpoints..............................................15
Alarms ..............................................................15
Component Failure...........................................16
Component Description........................16
Operator Interface Touch Screen......................16
Unit/Compressor Controller Description..........16
Navigating ........................................................17
Unit Controller.......................................19
Unit Controller Setpoints..................................19
Faults, Problems, Warnings ..............................21
Unit Controller Functions.................................22
Compressor Controller......................... 23
Compressor Controller Setpoints......................24
Compressor Faults, Problems, Warnings..........25
Compressor Controller Functions.....................26
Compressor On-Board
Controllers............................................. 30
Interface Touch Screen......................... 32
Navigation ........................................................32
Screen Descriptions..........................................34
VIEW Screens ..................................................34
SET Screens......................................................39
SERVICE Screen..............................................52
HISTORY Screens............................................53
Download Data.................................................54
ACTIVE ALARM Screen ................................55
Unit Controller Menu Screens.............57
Menu Matrix.....................................................58
Compressor Controller Menu
Screens ................................................... 75
Menu Matrix.....................................................75
BAS Interface........................................77
*
Manufactured in an ISO Certified Facility
©2007 McQuay International. Illustrations and data cover the McQuay International product 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;
used by L
from AST ElectroFin Inc.; Modbus from Schneider Electric; FanTrol, MicroTech II, Open Choices, and SpeedTrol from McQuay
International. References to ARI and ETL apply to the WMC only.
ONMARK International under a license granted by Echelon Corporation; Compliant Scroll from Copeland Corporation; ElectroFin
LONMARK, LonTalk, LONWORKS, and the LONMARK logo are managed, granted and
2 OM WMC-3
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.
! WARNING
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 knowledgeable in the operation of the equipment being controlled..
! 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, 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 20°F to 130°F
(-7°C to 54°C) with a maximum relative humidity of 95% (non-condensing).
HAZARD IDENTIFICATION INFORMATION
!
DANGER
Dangers indicate a hazardous situation which will result in death or serious injury if not avoided.
!
WARNING
Warnings indicate potentially hazardous situations, which can result in property damage, severe
personal injury, or death if not avoided.
!
CAUTION
Cautions indicate potentially hazardous situations, which can result in personal injury or
equipment damage if not avoided.
OM WMC-3 3
Features of the Control Panel
Control of leaving chilled water within a ±0.2°F (±0.1°C) tolerance. •
Display of the following temperatures and pressures on a 15-inch Super VGA touch-screen operator
•
interface (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
• Outside air temperature (optional)
• 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 evaporator and condenser 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 all accumulated 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
manufacture).
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
•
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 open protocols for most
4 OM WMC-3
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.
EXV
Electronic expansion valve, used to control the flow of refrigerant to the evaporator, controlled by the circuit
microprocessor.
OM WMC-3 5
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.
ms
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.
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).
6 OM WMC-3
SP
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-3 7
elie
General Description
Major Components
Figure 1, Major Component Location
Unit Control Panel
Evaporator
Relief Valve
Operator
Interface
Panel
Condenser
f
R
Optional Unit
Disconnect
Switch & Single
Point Power
Connection
Compressor #1 with
On-Board Controls
Circuit #1
Power Panel
Electronic Expansion Valve
Compressor #2
with On-Board
Controls
Circuit #2
Power
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.
8 OM WMC-3
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
Comm. Module
Universal
pLAN
OPERATOR
INTERFACE
TOUCH-SCREEN
UNIT
CONTROLLER
#1 COMPRESSOR
CONTROLLER
#2 COMPRESSOR
CONTROLLER
BAS
Onboard
Control
Onboard
Control
Color Graphics
Touch-Screen Interface
View Data, Input Setpoints
Stores History
UNIT
Analog Inputs
Analog Outputs
Digital Inputs
Digital Outputs
COMPRESSOR
Analog Inputs
Analog Outputs
Digital Inputs
Digital Outputs
OM WMC-3 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
SW5, Emergency
Shutdown Switch,
Outside Panel
USB Port Located on
PC Located in this Area
Compressor #1
Controller
Compressor #2
Controller
Figure 4, Switch Locations
Compressor #1 Switch
Compressor #2 Switch
Unit Switch
Circuit breaker
10 OM WMC-3
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 is typically
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.
!
WARNING
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.
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 10 on page 31. 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-3 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 seconds.
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
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.
any one of the following tests is true:
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.
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 twochiller system. With each compressor having its ‘Nominal Capacity’ defined, then the network, which is load
12 OM WMC-3
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
Communication Setup
The 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.
RS485 communication wiring between chillers should be field wired before start-up and installed as a
NEC Class 1 wiring system.
Table 1, Address DIP Switch Settings for Controllers Using Multi-chiller communication
Chiller Comp 1 Comp 2
A
B
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
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.
There are six Binary DIP Switches: Up is ‘On’, indicated by ‘1’. Down is ‘Off’, indicated by ‘0’. They
3.
are slide and not rocker switches. They are located on the upper-left corner of the face of the controller.
Operator
Interface
Reserved
Operator Interface Touch Screen (OITS) Settings
Settings for any type of linked multiple compressor operation must be made to the MicroTech II controller.
Settings on a dual compressor unit 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 Compressors ON – SETPOINTS - MODES screen, Selection #10 = 2 for a WMC, 4 for 2 WMCs.
Sequence and Staging – SETPOINTS - MODES screen, Selection #11 & #13; #12 & #14. 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 #10. The setting is the compressor design tons.
Compressors on dual units are always of equal capacity.
Communication Setup
1. With no communication connections between chillers, disconnect control power and set the DIP switches
as shown in
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.
OM WMC-3 13
Table 1.
4. Connect chillers together (pLAN, RS485, between J6 connections on each unit’s isolation boards. The
boards are not furnished, separate RS485 isolators must be field supplied.
5.
Verify correct nodes on each OITS Service Screen. See Figure 28 on page 52.
Operating Limits:
Maximum standby ambient temperature, 130°F (55°C)
Minimum operating ambient temperature (standard), 35
Leaving chilled water temperature, 38
Maximum operating evaporator inlet fluid temperature, 66
Maximum startup evaporator inlet fluid temperature, 90
Maximum non-operating inlet fluid temperature, 100
Minimum condenser water entering temperature, 55
Maximum condenser entering temperature, 105F (40.6C)
Maximum condenser leaving temperature, 115F (46.1C)
°F to 60°F (3°C to 15°C)
Low Condenser Water Temperature Operation
When the ambient wet bulb temperature is lower than design, the entering condenser water temperature can
be allowed to fall to improve chiller performance. This is especially true of an advanced design such as the
McQuay WMC chiller that features variable compressor speed.
It is an engineering fact that as the compressor discharge pressure is reduced, the amount of power to pump a
given amount of gas also is reduced. The reduction can result in significant energy savings.
°F (2°C)
°F (19°C)
°F (32°C)
°F (38°C)
°F (12.8°C)
However, as with most centrifugal chiller applications, a tower bypass valve must be installed and must be
controlled by the chiller MicroTech II controller.
arrangements. The “Cold Weather” scheme provides better startup under cold ambient air temperature
conditions. The check valve may be required to prevent entraining air at the pump inlet.
Figure 5, Bypass, Mild Weather Operation
Figure 5 illustrates two temperature actuated tower bypass
Bypass, Cold Weather Operation
14 OM WMC-3
Operating the Control System
Interface Panel On/Off
The Operator Interface Panel is turned on and off with a switch located at the lower front of the panel. Screen
control buttons are located to either side of it and elicit on-screen prompts when pressed.
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 botton.
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 10 on page 31).
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
except in an emergency when the OITS is unavailable.
40. Setpoints can also be changed in the unit controller, but this is not recommended
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.
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.
OM WMC-3 15
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.
Selected information from the OITS panel can be down-loaded
via a USB port located in the unit control panel.
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. The unit controller can also have an optional module to provide
communication for a BAS using standard open protocols.
16 OM WMC-3
A
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 6, Controller Keypad
Key-to-Screen Pathway
Air Conditioni ng
<
LARM
<
VIEW
<
SET
MENU Key
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 top-level 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 58 Page 60
Compressor Page 75 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,
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 6. One of these choices can then be selected by pressing
the key connected to it via the pathway shown in the figure.
OM WMC-3 17
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.
After selecting this second level, the desired screen can be acquired using the arrow keys. A typical
c)
final screen is shown below.
Pressing the MENU key from any menu screen will automatically return you to the MENU mode.
Figure 7, Typical Menu Display and Keypad Layout
MENU Key
Air Conditioni ng
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)
After pressing the MENU button, the top-level menu screen will
show:
(data)
< ALARM
< VIEW
< SET
After pressing the “VIEW” menu button, a menu screen will
show:
<
VIEW < COMPRESSOR
< UNIT
< EVAPORATOR
After pressing the “COMPRESSOR” menu button, the selected
data screen will show;
< CONDENSER
VIEW COMP (n)
(screen n data)
(screen n data)
(screen n data)
.
18 OM WMC-3
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.
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 Water
2
Temperature
Entering Condenser Water
3
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 Pump OFF Pump ON
2 Evaporator Water Pump #2 Pump Contactor Pump OFF Pump ON
3 Condenser Water Pump #1 Pump Contactor Pump OFF Pump ON
4 Condenser Water Pump #2 Pump Contactor Pump 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 Alarm 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%
4 Y3 Electronic Expansion Valve 0 to 10 VDC 0 to 100% Open
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
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:
Range column.
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).
OM WMC-3 19
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. 50
Control Source KEYPAD
Display Units N O --
Language ENGLISH ENGLISH, (TBD) N O -BAS Protocol NONE
Leaving Water
Cool LWT M O Pg. 11, Pg. 51
Startup Delta T M O Pg. 11, Pg. 51
Shutdown Delta T M O Pg. 11, Pg. 51
LWT Reset Type NONE NONE, RETURN, 4-20mA N M Pg. 22
Max Reset Delta T N M Pg. 22
Start Reset Delta T N M Pg. 22
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. 46
Tower Stages 2 1 to 4 N M Pg. 46
Stage Up Time 2 min 1 to 60 min N M Pg. 46
Stage Down Time 5 min 1 to 60 min N M Pg. 46
Stage Differential (Temp) N M Pg. 46
Stage Differential (Lift) 6.0 psi 1.0 to 20.0 psi N M Pg. 46
Stage #1 On (Temp) N M Pg. 46
Stage #2 On (Temp) N M Pg. 46
Stage #3 On (Temp) N M Pg. 46
Stage #4 On (Temp) N M Pg. 46
Stage #1 On (Lift) 35 psi 10 to 130 psi N M Pg. 46
Stage #2 On (Lift) 45 psi 10 to 130 psi N M Pg. 46
Stage #3 On (Lift) 55 psi 10 to 130 psi N M Pg. 46
Stage #4 On (Lift) 65 psi 10 to 130 psi N M Pg. 46
Cooling Tower Valve / VFD
Valve/VFD Control None
Valve Setpoint (Temp) N M Pg. 46
Valve Setpoint (Lift) 30 psi 10 to 130 psi N M Pg. 46
Valve Deadband (Temp) N M Pg. 46
Valve Deadband (Lift) 4.0 psi 1.0 to 20.0 psi N M Pg. 46
°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, Auto
Pump #1 Only, Pump #2 Only, Auto
None, Valve Setpoint, Valve Stage,
VFD Stage, Valve SP/VFD Stage
KEYPAD, BAS,
DIGITAL INPUT
NONE, BACnet, LonWorks,
MODBUS, N2
Lead, #1 Primary, #2 Primary
Lead, #1 Primary, #2 Primary
N O Pg.
N M Pg.
N M Pg.
N M Pg.
N M Pg.
Continued on next page
Manual
Reference
50
50, Pg 77
65
65
46
20 OM WMC-3
Description Default Range Type PW
Stage Down @ 20% 0 to 100% N M Pg. 46
Stage Up @ 80% 0 to 100% N M Pg. 46
Valve Control Range (Min) 10% 0 to 100% N M Pg. 46
Valve Control Range(Max) 90% 0 to 100% N M Pg. 46
Valve Type
Minimum Start Position 0% 0 to 100% N M Pg. 46
Minimum Position @ N M Pg. 46
Maximum Start Position 100% 0 to 100% N M Pg. 46
Maximum Position @ N M Pg. 46
Error Gain 25 10 to 99 N M Pg. 46
Slope Gain 25 10 to 99 N M Pg. 46
NC
(To Tower)
60 °F 0 to 100 °F
90 °F 0 to 100 °F
NC, NO N M Pg.
Manual
Referance
46
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 Temperature
Sensor Fault
No flow indicated for (5 sec) with Evaporator Pump #1 ON
AND [the other pump is available (per the Evap Pump SP)
AND has not faulted]
No flow indicated for (5 sec) with Evaporator Pump #2 ON
AND [the other pump is available (per the Evap Pump SP)
AND has not faulted]
No flow indicated for (5 sec) with Condenser Pump #1 ON
AND [the other pump is available (per the Evap Pump SP)
AND has not faulted]
No flow indicated for (5 sec) with Condenser Pump #2 ON
AND [the other pump is available (per the Evap Pump SP)
AND has not faulted]
Sensor fault AND leaving water reset is 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.
OM WMC-3 21
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 Automatic
Sensor is open or shorted Annunciation Automatic
Sensor is open or shorted Annunciation Automatic
Sensor is open or shorted Annunciation Automatic
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 Type 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)
(54.0°F)
(temperatures are examples only)
Max Reset Delta T
(10.0°F)
Cool LWT Set-Point
(44.0°F)
0 ma
4 ma
20 ma
22 OM WMC-3
Compressor Controller
The compressor controller's primary function is controlling and protecting the compressor. No setpoints are
input to it. There is one compressor controller for each compressor on the unit. The compressor controller
receives, processes, and sends data to the unit controller, the compressor on-board microprocessors and to
external devices. With some operator intervention the compressor controller can operate the compressor if the
operator interface touch screen is unavailable. Inputs and outputs are as follows:
Table 9, Compressor Controller, Analog Inputs
# Description Signal Source Range
Leaving Evaporator Water
1
Temperature
2 Spare
3 Motor Current 0 to 5 VDC 0 to 125% RLA
Table 10, Compressor Controller, Digital Inputs
# Description Signal Signal
1 Manual Off 0 VAC (Off) 24 VAC (Auto)
2 Spare
3 Spare
4 Spare
5 Spare
6 Spare
7 Evaporator Water Flow Switch 0 VAC (No Flow) 24 VAC (Flow)
8 Condenser Water Flow Switch 0 VAC (No Flow) 24 VAC (Flow)
9 Spare
NTC Thermistor
(10k@25°C)
-58 to 212°F
Table 11, Compressor Controller, Analog Outputs
# Description Output Signal Range
1 Spare
Table 12, Compressor Controller, Digital Outputs
# Description Load Output OFF Output ON
1 Compressor Off Emer. Solenoid Circuit Breaker ON
2 Spare
3 Spare
4 Spare
5 Spare
6 Spare
7 Spare
8 Inter Lock Solenoid Comp Disabled OFF Comp. Enabled ON
9 Spare
Circuit Breaker
OFF
OM WMC-3 23
Compressor Controller Setpoints
The following parameters in Table 13 are remembered during power off, are factory set to the Default value
and can be adjusted to any value in the
Type: column defines whether the setpoint is part of a coordinated set of duplicate setpoints in different
The “
controllers. The possibilities are given below:
• N = Normal setpoint - Not copied from or to any other controller.
• D = Duplicate setpoint. Setpoint is duplicated (same value) in all compressor controllers on the same
chiller.
• G = Group setpoint. Setpoint is duplicated (same value) in all compressor controllers on all chillers in a
group.
• 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).
At power-up the slave controller checks if the master 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.
PW (password) column indicates the password that must be active in order to change the setpoint. Codes
The
are as follows:
O = Operator, M = Manager, T = Technician (not available through the 4x20 display/keypad)
The following table groups setpoints that relate to compressor operation and are stored, for the most part, in the
compressor controllers. All settings are made through the OITS, indiscriminately as to whether they are “unit”
or “compressor.”
Table 13, Compressor Controller Setpoints
Description Default Range Type PW
Motor Amps
Demand Limit OFF OFF, ON N O
Minimum Amps 40% 20 to 80% N T
Maximum Amps 100% 40 to 100% N T
Soft Load OFF OFF, ON D M
Begin Amp Limit 40% 20 to 100% N M
Soft Load Ramp 5 min 1 to 60 min D M
Maximum Rate D M
Minimum Rate D M
Staging
Mode Normal
Sequence # 1
Maximum Compressors ON 16 1-16 G M
Stage Delta T 1.0 0.5-5.0 G M
Full Load 120 sec 30 to 300 sec N T
Absolute Capacity 100 Tons 0 to 9999 Tons D T
Timers
Start-Start 40 min 15 to 60 min N M
Stop-Start 3 min 3 to 20 min N M
Source No Start D T
Continued next page.
Description Default Range Type PW Manual
Range column.
0.5 °F/min 0.1 to 5.0 °F/min
0.1 °F/min 0.0 to 5.0 °F/min
Normal, Efficiency,
Pump, Standby
1,2, … (# of
Compressors)
70 °F 50 to 100 °F
Manual
Reference
N M
N M
24 OM WMC-3
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