OMM 1008-1 21
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, Controller Limit Alarms
Description Occurs When: Action Taken Reset
Evaporator Pump #1
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]
Start pump #2 Manual
Evaporator Pump #2
Fault
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]
Start pump #1 Manual
Condenser Pump #1
Fault
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]
Start pump #2 Manual
Condenser Pump #2
Fault
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]
Start pump #1 Manual
Entering Evaporator
Water Temperature
Sensor Fault
Sensor fault AND leaving water reset is based on entering
water
Reset mode is
set to No Reset
Manual.
(Reset mode
goes back to
Entering
Water)
Warnings
The following “alarms” only generate a warning message to the operator. Chiller operation is not affected.
Table 8, Controller Warnings
Description Occurs When: Action Taken Reset
Entering Evaporator Temperature
Sensor Fault
Sensor is open or shorted Annunciation Automatic
Entering Condenser Temperature
Sensor Fault
Sensor is open or shorted Annunciation Automatic
Leaving Condenser Temperature
Sensor Fault
Sensor is open or shorted Annunciation Automatic
Liquid Line Refrigerant
Temperature Sensor Fault
Sensor is open or shorted Annunciation Automatic
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:
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