Load Balancing
When the LOAD BALANCE OPT ION is enabled, the lead c hil ler will set the ACTIVE
DEMAND LIMIT in the lag chiller to the lead chiller’s COMPRESSOR MOTOR LOAD value.
This value has limit s of 40% to 100%. W hen setting the la g chiller ACTIVE DE MAND LIMIT, the
CONTROL POINT shall be m od ified to a value of 3° F (1. 67° C) less than the lead chille r’s
CONTROL POINT value. If the LOAD BALANCE OPTION is disabled, the ACTIVE DEMAND
LIMIT and the CONTROL POI NT are forced to the same val ue as the lead chiller .
Auto. Restart After Pow er Failure
When an autorestart cond ition occurs, each chi ller may have a delay add ed t o the start-up
sequence, dependin g on it s lead/lag configu r at ion. The lead chiller does no t have a delay. The
lag chiller has a 45 second del ay. The standby chiller has a 90 s ec o nd delay. The delay time is
added after the chiller wat er flow verificatio n. The PIC controls ensure that the guide vanes are
closed. After the guide v an e position is confir m ed, the delay for lag and sta ndb y chiller occurs
prior to energizing th e oil pump. The normal st art-up sequence the n continues. The au to. restart
delay sequence occurs whether the chiller is in CCN or LOCAL mode and is intended to stagger
the compressor motors fro m being energized sim ul taneously. This wil l help reduce the inrus h
demands on the building power system.