44 TGZ 040A through TGZ 190A OMM TGZ-1
Pump Selection
The pump output used will be determined by the Cond Pump Control set point. The setting
allows the following configurations:
#1 only – Pump 1 will always be used.
#2 only – Pump 2 will always be used.
Auto – The primary pump is the one with the least run hours, the other is used as a backup.
#1 Primary – Pump 1 is used normally, with pump 2 as a backup.
#2 Primary – Pump 2 is used normally, with pump 1 as a backup.
Primary/Standby Pump Staging
The pump designated as primary will start first. If the condenser state is start for a time
greater than the re-circulate timeout set point and there is no flow, then the primary pump
will shut off and the standby pump will start. When the condenser is in the run state, if flow
is lost for more than half of the flow proof set point value, the primary pump will shut off
and the standby pump will start. Once the standby pump is started, the flow loss alarm logic
will apply if flow cannot be established in the condenser start state, or if the flow is lost in
the condenser run state.
Auto Control
If auto pump control is selected, the primary/standby logic above is till used. When the
condenser is not in the run state, the run hours of the pumps will be compared. The pump
with the least hours will be designated as the primary at this time
Condenser Water Flow Loss
The Condenser Water Flow Loss logic allows the Unit to shutdown compressors on a loss
of flow up to two times every twenty-four hours before locking the unit out on a Condenser
Flow Loss Alarm.
If there are no compressors running when Condenser Water Flow Loss is indicated the Unit
Status changes to Auto:Wait for flow. The condenser water pump state changes to Start
and no alarms are indicated.
If a Condenser Water Flow Loss occurs while a compressor is running all of the running
compressors will be shutdown. The Alarm indicators are turned On and the Circuit
Status for any circuit with running compressors becomes Off: Ready, the Unit Status
becomes Auto: Wait For Flow and the condenser water pump state changes to Start
When flow is reestablished the Unit Status becomes Auto: Recirculate while the Condenser
Flow Recirculation Timer counts down. If there is continuous evaporator water flow
while the Condenser Recirculation Timer counts down the Alarm indicator is turned
off, and the Unit resumes normal start up procedures based on water temperature and
cycle timers.
If second Condenser Water Flow Loss occurs within twenty-four hours the process
described above is repeated.
If a third loss of flow is indicated in twenty-four hour time frame the Unit will shut down
on an Condenser Water Flow Loss alarm and it will be locked out until this alarm is
manually cleared.
The twenty-four hour timer that limits the auto restart is reset when the control clock rolls
over 00:00 each night.
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