Carrier 19XL specifications

Safety Controls Ð The PIC monitors all safety control inputs, and if required, shuts down the chiller or limits the guide vanes to protect the chiller from possible damage from any of the following conditions:

·high bearing temperature

·high motor winding temperature

·high discharge temperature

·low oil pressure

·low cooler refrigerant temperature/pressure

·condenser high pressure or low pressure

·inadequate water/brine cooler and condenser ¯ow

·high, low, or loss of voltage

·excessive motor acceleration time

·excessive starter transition time

·lack of motor current signal

·excessive motor amps

·excessive compressor surge

·temperature and transducer faults

Starter faults or optional protective devices within the starter can shut down the chiller. These devices are dependent on what has been purchased as options.

If compressor motor overload occurs, check the motor for grounded or open phases before attempting a restart.

If the controller initiates a safety shutdown, it displays the fault on the LID display with a primary and a secondary message, and energizes an alarm relay in the starter and blinks the alarm light on the control center. The alarm is stored in memory and can be viewed in the PIC alarm table along with a message for troubleshooting.

To give a better warning as to the operating condition of the chiller, the operator also can de®ne alert limits on vari- ous monitored inputs. Safety contact and alert limits are de®ned in Table 3. Alarm and alert messages are listed in the Troubleshooting Guide section, page 66.

SHUNT TRIP Ð The shunt trip function of the PIC is a safety trip. The shunt trip is wired from an output on the SMM to a shunt trip-equipped motor circuit breaker. If the PIC tries to shut down the compressor through normal shutdown pro- cedure but is unsuccessful for 30 seconds, the shunt trip out- put is energized and causes the circuit breaker to trip off. If ground fault protection has been applied to the starter, the ground fault trip will also energize the shunt trip to trip the circuit breaker.

Default Screen Freeze Ð Whenever an alarm occurs, the LID default screen will freeze displaying the condition of the chiller at the time of alarm. Knowledge of the operating state of the chiller at the time an alarm occurs is useful when troubleshooting. Current chiller information can be viewed on the Status tables. Once all existing alarms

are cleared (by pressing the RESET softkey), the default

LID will return to normal operation.

Motor Cooling Control Ð Motor temperature is reduced by refrigerant entering the motor shell and evap- orating. The refrigerant is regulated by the motor cooling relay. This relay will energize when the compressor is run- ning and motor temperature is above 125 F (51.7 C). The relay will close when motor temperature is below 100 F (37.8 C). Note that there is always a minimum ¯ow of refrigerant when the compressor is operating for motor cool- ing; the relay only controls additional refrigerant to the motor.

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