Zamil MAC-240, Installation, Operation & Maintenance Manual

Page: 33 / 67

32
FAULT DESCRIPTION PROBABLE CAUSE
Low Refrigerant pressure
High pressure at discharge line
Fault on generator
Fuel Level is Low (10%)
1. No control power (24V circuit)
2. No Control Power (230V)
3. Serial cable (UIB to MB) loose or
Defective
CORRECTIVE MEASURE
- Check hot gas by-pass solenoid if not
getting activated, replace if damaged
- Check for leaks in suction line, re-
pair and add refrigerant charge.
- Check expansion valve and replace
if defective.
- Reduce refrigerant charge if system
is overcharged.
- Check error code on LCD of genera-
tor set module. Refer generator’s
manual for nature of fault and pos-
sible corrective measure.
- Switch “OFF” the engine and add
fuel.
- Check control fuses F5/F6 and re-
place if blown.
- Check control fuses F1 to F4 and
replace if blown.
- Check emergency stop button and
pull if it is in “pushed” position.
- Replace cable
SYMPTOM
Compressor
Stopped or
Not Starting
Mains Power
Loss
No Control
Power (LCD
not Illumi-
nated)
LCD DISPLAY
# Suction Pres-
sure Low
# Discharge
Pressure High
Generator
Low Fuel
-
7. PROTECTION DEVICES
7.1 VOLTAGE MONITORING RELAY
This device protects the motors in the equipment from faults such as; under or over voltage, phase imbalance, and phase
reversal of the main supplied voltage. When the device sensed such faults, it will cut-off the power supply in the control
circuit thereby cutting OFF power to the motors. The voltage monitor relay will re-set automatically when power is brought
back to normal conditions. The trip settings and other details are shown in the table below:
LINE VOLTAGE
RANGE
UNDER VOLTAGE
TRIP
90%
190 - 480 VAC
TRIP & RE-SET VOLTAGE (% OF SET POINT)
OVER VOLTAGE
PHASE IMBALANCE
RE-SET
93%
TRIP
110%
RE-SET
107%
TRIP
6%
RE-SET
4.5%
7.2 THERMAL OVERLOAD RELAYS
Each compressor and condenser fan motor in the equipment is having internal thermal protection for its winding and an
external overload relay is provided to protect the motor against overload. The external overload relay is set to trip when
the motor drawn current reached up to 20% more than its rated current.
7.3 CIRCUIT BREAKERS
Circuit breakers are devices designed to open and close a circuit by non-automatic means, and to open the circuit
automatically on a predetermined over current due to abnormal circuit conditions such as a short circuit. All the motors in
the equipment, the ACU section, and the generator output are provided with circuit breakers.
7.4 DISCHARGE PRESSURE SWITCH
Each refrigeration system of the equipment is provided with a protection from excessive discharge pressures. The unit’s
control cuts-off the compressor’s operation at a pre-set discharge pressure value. Aside from the pressure sensor
(transducer), an added pressure switch is also provided for additional protection in each system in case of high discharge
pressures.