Engineering manual - UniSAB III 1.10.8
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001930 en 2021.06
Alarms and shutdowns
2.2.7 Compressor motor overload
The reason for the shutdown is that within the time set in the Current overload timer, a motor current has
been measured continually. This current exceeds the actual set point value set for Motor current in Set
point 1 or Set point 2.
2.2.8 Discharge pressure overload
The reason for the shutdown is that within the time set in the Discharge overload timer, a discharge pres-
sure overload has been measured continually. This pressure level exceeds the alarm limit for high dis-
charge pressure.
2.2.9 High motor temperature
The reason for the shutdown is that the Thermistor input is open, i.e. the load on the input is above 3990
Ω.
2.2.10 Oil pump error (screw compressors)
The reason for the shutdown is that feedback from the oil pump motor is not set/does not disappear with-
in the time set in the Oil pump motor timer when the compressor starts/stops (i.e. the digital output oil
pump start is activated/deactivated) or that feedback from the motor disappears even briefly during
operation.
The shutdown functions as an alarm during operation i. e. after the prelubrication sequence has been
completed.
2.2.11 Oil pump error (SAB 80, S 50, S 70, S 93)
The reason for the shutdown is that the differential pressure (P3-P4) across the mechanical oil pump is
too low (i.e. lower than 0.5 Bar). This value can be set as Set point 1 for the oil pressure.
The shutdown is delayed 45 seconds after compressor start (same timer as for low oil pressure).
The shutdown is only activated when the discharge pressure is lower than 16 Bar. This value can be set
as Set point 2 for the oil pressure. At a discharge pressure level of approx. 16 Bar, the pump cannot be
expected to generate a positive relative pressure because of the shunt valve. There is therefore no shut-
down surveillance of the differential pressure across the oil pump.
2.2.12 Full flow pump error (screw compressors)
The reason for the shutdown is that feedback of the full flow pump motor is not set/does not disappear
within the time set in the Full fl. Pump motor timer when the motor starts/stops (i.e. the digital output full
flow pump start is activated/deactivated) or that feedback from the motor disappears even briefly during
operation.
The shutdown functions as an alarm during operation i. e. after the prelubrication sequence has been
completed.
2.2.13 Cooling fan error
The shutdown is activated when feedback from the electrical cooling fan motor is not set/does not disap-
pear within the time limit set in the Full fl. Pump motor timer when the motor starts/stops (i.e. the digital
output cooling fan is activated/deactivated) or that feedback from the motor disappears even briefly dur-
ing operation.
2.2.14 Oil rectifier error
The reason for the shutdown is that suction gas superheat has not exceeded the value set in Set point 1
before the Rect. Disable. timer has expired although the Oil rectifier configuration has been set and the
compressor is running.
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