York Millennium YCAS 310, Установка, эксплуатация и обслуживание

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YORK INTERNATIONAL
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1.10 COMPRESSOR HEATER
The Compressor Heater in each compressor will be
ON for the first five minutes after the compressor is
shut down. Then the heater is controlled by discharge
temperature. If the heater is ON and the discharge tem-
perature rises above 170°F will shut off. If the heater is
OFF and the discharge temperature falls below 100°F,
it will turn ON. The heater is controlled by the micro-
processor.
The purpose of the heater is to prevent the migration
of refrigerant into the compressor during shutdown,
assuring proper lubrication of the compressor on start-
up.
Anytime power is removed from the chiller for more
than an hour, 115VAC control power should be reap-
plied to allow the compressor heaters to remain on for
24 hours prior to restart.
1.11 EVAPORATOR HEATER
The evaporator heater prevents water standing in the
evaporator from freezing. Whenever the outdoor am-
bient temperature drops below 40°F, the microproces-
sor will turn the evaporator heaters ON. If temperature
rises above 45°F, the heater will be turned off.
1.12 LEAD LAG COMPRESSOR SELECTION
2 COMPRESSOR
LEAD/LAG COMPRESSOR SELECTION
The chiller may be set up for AUTO or MANUAL Lead/
Lag. This is accomplished by properly configuring the
S1 Dip Switches on the Microprocessor Board. Details
for configuring the switches are discussed in the “Dis-
play Key” Section under OPTIONS key.
When AUTO Lead/Lag is utilized, the micro attempts
to balance run time between the two compressors. A
number of conditions can occur which will prevent this
from happening. Factors determining lead/lag selec-
tion and the resulting lead/lag determination are dis-
cussed below:
1. The micro automatically defaults the lead to SYS 1
and the lag to SYS 2 if both compressors are ready
to start (Anti-recycle Timers timed out) and compres-
sors have equal run time.
2. If both compressors are ready to start (Anti-recycle
Timers timed out), the compressor with the lowest
run hours will start first.
3. If both compressors are waiting to start (Anti-recycle
Timers are not timed out), the micro will assign the
lead to the compressor with the shortest anti-recycle
time in an effort to provide cooling quickly.
4. If the lead compressor is locked out, faulted and
waiting to restart, SYS switch on the micro boards is
off, or a run permissive is keeping an individual sys-
tem from running, the lag compressor is swapped to
the lead. This is true regardless of whether the lag
compressor is on or off.
If MANUAL Lead/Lag is selected, an external “dry” con-
tact (switch) must be wired into the chiller. This contact
is field supplied. With the contact open, SYS 1 is placed
in the lead. When the contact is closed, SYS 2 will be
lead system.
MANUAL Lead/Lag selection will be automatically over-
ridden by the micro to allow the lag compressor to au-
tomatically become the lead anytime the selected lead
compressor shuts down due to a lock-out, lead system
faults and is waiting to restart, lead system switch on
the micro board is in the OFF position, or if a run per-
missive is keeping the lead of the system off. Auto-
matic switchover in the MANUAL mode is provided to
try to maintain chilled liquid temperature as close to
setpoint as possible.
The “dry” contact for manual lead/lag selection is wired
into terminals 13 and 19 of the TB3 Terminal Block.
The location of these contacts is shown in Fig. 1.13.
1.13 – TB3 LOCATION MANUAL LEAD LAG
27962A
TB3