STANDARD CONTROL & SAFETY DEVICES

STANDARD CONTROL & SAFETY DEVICES

MICROPROCESSOR CONTROLLER: This controller monitors analog and digital inputs to achieve precise control & safety
functions of the unit.

COMPRESSOR IN-BUILT PROTECTION DEVICE: Protects the compressor by monitoring:
A) Motor winding temperature in case of overload.
B) Discharge gas temperature in case of overheating.
C) Phase reversal for direction of rotation.

STARTERS: The starter is operated by the control circuit and provides power to the compressor motors. These devices are
rated to handle safely both RLA and LRA of motors.

CRANKCASE HEATERS: Each compressor has immersion type crankcase heater. The compressor crankcase heater is
always on when the compressors are de-energized. This protects the system against refrigerant migration, oil dilution and
potential compressor failure.

HIGH PRESSURE SWITCH: This switch provides an additional safety protection in the case of excessive discharge
pressure.

UNDER & OVER VOLTAGE AND PHASE PROTECTION: Protects against low & high incoming voltage as well as single phasing, phase reversal and phase imbalance by de-energizing the control circuit. It is an automatic reset device, but it can be set up for manual reset.

COMPRESSOR CIRCUIT BREAKERS: Protects against compressor branch circuit fault. When tripped (manually or automatically), the breaker opens the power supply to the compressor and control circuit through auxiliary contacts.

HARD WIRE TO BMS: Communicate the controller to site BMS thru hard wire:
1. Remote Unit Enable/Disable (Start/Stop) – a digital input to the controller that allows the user to Start and normally
shutdown the chiller unit from remote or control room.
2. Unit General Alarm – a digital output signal from the controller to indicate that alarm is existing in the chiller.
3. Compressor Circuit Enable/Disable – a digital input to the controller that allows the user to Start and normally shutdown
the compressor from remote or control room.
4. Second Temperature Control Set point – a digital input to the controller that allows the user to enable the second set
point. Value for the second temperature control set point can be modified at the controller parameter.
5. Set point correction – an analog input to the controller that allows the user adjust the temperature control set point via
external analog signal (4-20mA).