Technical information

If refrigerant discharge pressure (PT-2) goes above 270 psig
(for water-cooled models) or 350 psig (for air-cooled models)
the compressor shuts down. The Alarm light illuminates and
the PLC indicates "High Discharge Pressure" for the compres-
sor on a single compressor system and compressor 1 on a dual
compressor system. The PLC will indicate "High Discharge
Pressure 2" for compressor 2 on a dual compressor system.
The process pump will remain running until the Stop button is
pressed.
If the compressor overloads and trips the MSP, the compressor
shuts down. The Alarm light illuminates and PLC indicates
"Compressor Overload" for the compressor on a single com-
pressor system and compressor 1 on a dual compressor sys-
tem. The PLC indicates "Compressor 2 Overload" for com-
pressor 2 on a dual compressor system. The MSP must be
reset inside the control panel. The process pump remains run-
ning until the Stop button is pressed.
If the process or recirculation pump overloads and trips the
MSP, the compressor and pump(s) shut down. The MSP must
be reset inside the control panel. The Alarm light illuminates
and PLC indicates "Pump Overload" for a process pump over-
load.
The 3.5 and 5 hp compressors (used on PCW-3.5, PCW-5,
PCA-3.5 and PCA-5) have a high discharge refrigerant tem-
perature switch (TSHH-1). If the switch detects a high dis-
charge temperature the compressor shuts off immediately. The
alarm light illuminates and the PLC indicates "High Discharge
Temperature". The process pump remains running until the
Stop button is pressed.
Each chiller has a differential pressure switch (PDS-2) on the
evaporator. This switch indicates a high-pressure drop through
the Evaporator and strainer, usually the result of a dirt strainer
or fouled evaporator. When this condition is detected, the
alarm light (and strobe) illuminate and the PLC indicates
"Evaporator Filter Fault". The compressor and pump(s) con-
tinue to run. Press the Enter button to clear the message from
the screen. The message continues to display every 60 min-
utes.
PLC C
ONTROL
ALARM
CONDITIONS
CONT’D
High Discharge Temperature
Evaporator Filter Fault
Pump Overload
Compressor Overload
Compressor Overload 2
High Discharge Pressure
High Discharge Pressure 2
UGH024/1103 Portable Chillers
TROUBLESHOOTING
6-21