Carrier 17/19EX - Manual (Page 80)

If the controller initiates a safety shutdown, it displays the fault on the LID 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 History
table along with a message for troubleshooting.
To give a better warning as to the operating condition of the machine, the operator also can
define alert limits on various monitored inputs. Safety contact and alert limits are defined in
Table 3 . Alarm and alert messages are listed in the Troubleshooting Guide section.
Shunt Trip
The optional shunt trip function of the PIC is a safety trip. The shunt trip is wired from an
output on the SMM to the motor circuit breaker. If the PIC tries to shut down the compressor
through normal shutdown procedure but is unsuccessful for 30 seconds, the shunt trip output 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.
CAUTION CAUTION
!
If compressor motor overload or ground fault occurs, check the motor for
grounded or open phases before attempting a restart.