Carrier 19XL - Manual (Page 102)

6. The configured LAG START TIMER entry has elapsed. The LAG START TIMER shall be
started when the lead chiller ramp loading is completed. The LAG START TIMER entry is
accessed by selecting Lead/Lag from the Equipment Configuration table of the Service
menu.
When all of the above requirements have been met, the lag chiller is forced to a START
mode. The PIC control then monitors the lag chiller for a successful start. If the lag chiller fails to
start, the standby chiller, if configured, is started.
Lag Chiller Shutdown Requirements
The following conditions must be met in order for the lag chiller to be stopped.
1. Lead chiller COMPRESSOR MOTOR LOAD value is less than the lead chiller percent
capacity plus 15%.
Note: Lead chiller percent capacity = 100 – LAG PERCENT CAPACITY
The LAG PERCENT CAPACITY value is configured on the Lead/Lag Configuration screen.
2. The lead chiller chilled water temperature is less than the CONTROL POINT plus 1/2 of the
WATER/BRINE DEADBAND.
3. The configured LAG STOP TIMER entry has elapsed. The LAG STOP TIMER is started
when the CHILLED WATER TEMPERATURE is less than the CHILLED WATER
CONTROL POINT plus 1/2 of the WATER/BRINE DEADBAND and the lead chiller