64 YORK INTERNATIONAL
FIG. 22 LOCATION OF THE MICROPROCESSOR BOARD
FIG. 23 ALARM CONTACT CONNECTION LOCATION
LD02092
26000A
26001A
A new lead/lag assignment is made whenever both com-
pressors shut down. The micro will assign the lead to the
compressor with the shortest anti-recycle time. This will
tend to balance run time between the two compressors.
AUTO Lead/Lag will cause the lag compressor to auto-
matically become the lead, anytime the compressor
currently in the lead shuts down due to a safety thresh-
old being exceeded. This is done to maintain water tem-
perature as close to setpoint as possible. Additionally,
the lag system will automatically become the lead any-
time the system switch on the microprocessor board of
the compressor currently in the lead is placed in the
OFF position. This is also done to maintain water tem-
perature as close to setpoint as possible.
If MANUAL Lead/Lag is selected, an external dry con-
tact (switch) must be wired into the chiller. This contact
is supplied by others. When the contact is closed, SYS
2 will be the lead system. With the contact open, SYS 1
is the lead.
Manual Lead/Lag selection can be automatically over-
ridden by the micro to allow the lag compressor to auto-
matically become the lead, anytime the selected lead
compressor shuts down due to a safety threshold being
exceeded. This is done to try to maintain water tem-
perature as close to setpoint as possible. No lead/lag
switchover will take place if the system switch on the
microprocessor of the lead compressor is placed in the
OFF position.
The dry contact for manual lead/lag selection is wired
into terminals 13 and 19. The location of these contacts
is shown below in Fig. 24.
MICROPROCESSOR
BOARD
SYSTEM SWITCHES 1-4
ON MICROPROCESSOR BOARD
To Next Page
Loading...
