36 WGS 130A to 190A OM WGS-5
Unit Events
The following unit events are logged in the event log with a time stamp.
Entering Evaporator Water Temperature Sensor Fault
Event description (as shown on screen): Evap EWT Sens Fault
Trigger: Sensor shorted or open
Action Taken: Return water reset cannot be used.
Reset: Auto reset when sensor is back in range.
Leaving Condenser Water Temperature Sensor Fault
Event description (as shown on screen): Cond LWT Sens Fault
Trigger: Sensor shorted or open AND unit is watercooled
Action Taken: None
Reset: Auto reset when sensor is back in range.
Circuit Stop Alarms
All circuit stop alarms require shutdown of the circuit on which they occur. Rapid stop
alarms do not do a pumpdown before shutting off. All other alarms will do a pumpdown.
The red button led on the circuit controller shall be turned on when any circuit stop alarm
occurs. It shall be turned off when all circuit alarms have been cleared. In addition, the
alarm status shall be sent to the unit control so the alarm output and the red button led on the
unit controller can be energized while alarms are active.
Alarm descriptions apply to both circuits, the circuit number is represented by ‘N’ in the
description.
Low Evaporator Pressure
Alarm description (as shown on screen): Evap Press Low N
Trigger: [Freezestat trip AND Compressor State = Run AND Low OAT Start not active
AND Evap Pressure Sensor Fault not active] OR [Evaporator Press < -10 psi AND startup
timer complete AND Evap Pressure Sensor Fault not active] and the compressor has been
running longer than the Startup Timer setting
Freezestat logic allows the circuit to run for varying times at low pressures. The lower the
pressure, the shorter the time the compressor can run. This time is calculated as follows:
Freeze error = Low Evaporator Pressure Unload – Evaporator Pressure
Freeze time = 70 – 6.25 x freeze error, limited to a range of 20-70 seconds
When the evaporator pressure goes below the Low Evaporator Pressure Unload set point, a
timer starts. If this timer exceeds the freeze time, then a freezestat trip occurs. If the
evaporator pressure rises to the unload set point or higher, and the freeze time has not been
exceeded, the timer will reset.
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the Unit Controller keypad if the evaporator
pressure is above –10 psi.
To Next Page
Loading...
Need help?
General
