Appendix A: Hardwired Chiller Control; Setting Up The Csm's Additional Chiller Data For A Hardwired Chiller; Table 27. Hardwired Chiller Config (Main > Configuration > Chiller Setup) - McQuay MicroTech II Operation Manual

Appendix A: Hardwired Chiller Control

This appendix provides information about using the CSM to control chillers via hardwired binary and analog inputs and
outputs. This option should be used when a serial communication option is not available since control, monitoring, and
alarm indication is reduced. Hardwired chillers have control features wired to a remote I/O module mounted near the
chiller's unit controller. The hardwired chiller's remote I/O module communicates with the CSM via a L
network. The CSM controls the chiller using the following outputs on the remote I/O module:
1. Remote Auto/Stop (Relay Output)
2. Evaporator pump enable – if the chiller is not controlling its own pumps (Relay Output)
3. Condenser pump enable – if the chiller is water cooled and not controlling its own pumps (Relay Output)
4. Chiller leaving water temperature setpoint reset (Analog Output)
5. Capacity limit (Analog Output)
The CSM will receive the following information through the remote I/O module's inputs:
1. Proof of evaporator water flow (Digital Input)
2. Proof of condenser water flow - on water cooled chillers (Digital Input)
3. Chiller alarm output (Digital Input)
4. Second chiller alarm output – if the chiller has multiple compressors, the chiller provides two alarm outputs
(Digital Input)
5. Compressor percent rated load amps - % RLA (Analog Input)
6. Optional chiller evaporator leaving water temperature (Analog Input)
7. Optional chiller condenser leaving water temperature (Analog Input)
Hardwired chillers are controlled by the CSM the same as a MicroTech II chiller with some exceptions. These differences
include limited chiller data, limited alarm information, and the limited Comm Loss control features.
Setting up the CSM's Additional Chiller Data for a Hardwired
Chiller
In addition to the Chiller Data that must be entered for all chillers on the Chiller Setup screen, the CSM also requires you to
enter certain additional details about a hardwired chiller. The variables are located on the Chiller Setup screen and
described in Table 27.
Table 27. Hardwired Chiller Config (Main > Configuration > Chiller Setup)
Name
Stop-to-Start Timer
Full Load % RLA Level
Running % RLA Level
% RLA Input Type
Voltage Signal At 100 % RLA
Nameplate RLA
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Description
This input tells the CSM how long to wait after this chiller is disabled before it can be made available to
enable again. Enter the same time period as the stop-to-start timer setting in the associated chiller unit
controller. Default = 00:05:00 (5 minutes).
This input tells the CSM when to consider the chiller to be at full load. When the % RLA of the chiller is
greater than this value, the CSM may begin the stage-up control process. Range = 1 to 99%.
Default = 90%.
This input defines the minimum measured % RLA from a hardwired chiller required to have that chiller
considered in the Running state. Below this level the chiller compressors are considered Off and the
chiller is not producing chilled water. Range = 5 to 50%. Default = 20%.
This input tells the CSM how % RLA will be sent from the chiller to the remote I/O modules analog
input. Range = % RLA from chiller (4-20 mA), % RLA from chiller (0-10 Vdc), Amps from 4-20 mA
output current transducer (CT). Default = % RLA from chiller (0-10 Vdc).
Only use this value if % RLA Input Type is set to "% RLA from chiller (4-20 mA)" or "% RLA from
chiller (0-10 Vdc)". This input tells the CSM what the voltage on the analog input (AI 1) will be to
represent 100% RLA. For example, a McQuay MicroTech Series 200 Centrifugal chiller outputs a 0-10
Vdc range which represents a % RLA range from 0% to 125%, this means that when the compressor is
running at 100% RLA it will output 8 Vdc. Range = from 4 to 10 Vdc. Default = 8.
If % RLA is sent from the chiller unit controller this property is not used. This input tells the CSM the
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