Carrier 19XL - Manual (Page 103)

COMPRESSOR MOTOR LOAD is less than the lead chiller percent capacity plus 15%. The
timer is ignored if the chilled water temperature reaches 3° F (1.67° C) below the
CONTROL POINT and the lead chiller COMPRESSOR MOTOR LOAD value is less than
the lead chiller percent capacity plus 15%.
Faulted Chiller Operation
If the lead chiller shuts down on an alarm (*) condition, it stops communication to the lag and
standby chillers. After 30 seconds, the lag chiller will now become the acting lead chiller and will
start and stop the standby chiller, if necessary.
If the lag chiller faults when the lead chiller is also faulted, the standby chiller reverts to a
stand-alone CCN mode of operation.
If the lead chiller is in an alarm (*) condition (as shown on the LID panel), the RESET softkey
is pressed to clear the alarm, and the chiller is placed in the CCN mode, the lead chiller will now
communicate and monitor the RUN STATUS of the lag and standby chillers. If both the lag and
standby chillers are running, the lead chiller will not attempt to start and will not assume the role
of lead chiller until either the lag or standby chiller shuts down. If only one chiller is running, the
lead chiller will wait for a start request from the operating chiller. When the configured lead
chiller starts, it assumes its role as lead chiller.