IOM 1206-1
45
Alarms
Alarms
Situations may arise that require some action from the chiller
or that should be logged for future reference. Alarms are
classified in the following sections using the Fault/Problem/
Warning scheme.
When any Unit Fault Alarm is active, the alarm digital output
should be turned on continuously. If both circuits have a
Circuit Fault Alarm active, the alarm digital output should be
turned on continuously. If no Unit Fault Alarm is active and
only one circuit has a Circuit Fault Alarm is active, the alarm
digital output should alternate five seconds on and five
seconds off continuously.
All alarms appear in the active alarm list while active. All
alarms are added to the alarm log when triggered and when
cleared. Entries in the log representing the occurrence of an
alarm will be preceded by ‘+’ while entries representing the
clearing of an alarm will be preceded by ‘-‘.
Unit Fault Alarms
PVM/GFP Fault
Trigger:
Power Configuration
=
Single Point and
PVM/
GFP Input #1 is open.
Action Taken:
Rapid stop all circuits
Reset:
Auto reset when input is closed for at least 5
seconds or if Power Configuration = Multi Point.
Evaporator Flow Loss
Trigger:
1: Evaporator Pump State = Run AND
Evaporator Flow
Digital Input = No Flow for time > Flow Proof Set Point
AND at least one compressor running
2: Evaporator Pump State = Start for time greater than
Recirc Timeout Set Point and all pumps have been tried
and Evaporator Flow Digital Input = No Flow
Action Taken:
Rapid stop all circuits
Reset:
This alarm can be cleared at any time manually via the keypad
or via the BAS clear alarm command.
If active via trigger condition 1:
When the alarm occurs due to this trigger, it can auto reset the
first two times each day with the third occurrence being
manual reset.
For the auto reset occurrences, the alarm will reset
automatically when the evaporator state is Run again. This
means the alarm stays active while the unit waits for flow, then
it goes through the recirculation process after flow is detected.
Once the recirculation is complete, the evaporator goes to the
Run state which will clear the alarm. After three occurrences,
the count of occurrences is reset and the cycle starts over if the
manual reset flow loss alarm is cleared.
If active via trigger condition 2:
If the flow loss alarm has occurred due to this trigger, it is
always a manual reset alarm.
Evaporator Water Freeze Protect
Trigger:
Evaporator LWT drops below evaporator freeze
protect set point and LWT sensor fault is not active.
Action Taken:
Rapid stop all circuits
Reset:
This alarm can be cleared manually via the
keypad, but only if the alarm trigger conditions no longer
exist.
Evaporator LWT Sensor Fault
Trigger:
Sensor shorted or open
Action Taken:
Normal stop all circuits
Reset:
This alarm can be cleared manually via the
keypad or BAS command, but only if the sensor is back
in range.
Outdoor Air Temperature Sensor Fault
Trigger:
Sensor shorted or open
Action Taken:
Normal stop of all circuits.
Reset:
This alarm can be cleared manually via the
keypad or via BAS command if the sensor is back in
range.
External Alarm
Trigger:
External Alarm/Event opens for at least 5
seconds and external fault input is configured as an
alarm.
Action Taken:
Rapid stop of all circuits.
Reset:
Auto clear when digital input is closed.