Lead/Lag Control
Note: Lead/lag control is only av ai lable on machines with PS I O Software Version 09 or hig her.
Lead/lag is a control system process that automatically starts and stops a lag or second
chiller in a 2-chiller water system. Refer to Figure 16 and Figure 17 for menu, table, and screen
selection informat ion . On machines that have PSI O software with Lead/Lag c apa bility, it is
possible to utilize t he P I C controls to perform the lead /lag function on 2 machine s. A third
machine can be added to the lead/lag system as a standby chiller to start up in case the lead or
lag chiller in the system has shut down during an alarm condition and additional cooling is
required.
Note: Lead/lag configura tion is viewed and edited under Lead/ Lag in the Equipm ent Configura-
tion table (located in t he S er v i ce menu). Lead/lag sta tu s during machine operatio n is
viewed in the M AINT04 table in the Control Al gorithm Status table. See Table 2.
Lead/Lag System Requirements:
all machines must have PS I O software capable of perf or m i ng the lead/lag funct ion
water pumps MUST be ener giz e d from the PIC controls
water flows should be con stant
CCN Time Schedules for all machines must be identic al