64
YORK INTERNATIONAL
9
Leak check compressors, fittings, and piping to
assure no leaks are present from improper han-
dling.
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9
START-UP COMPLETE
OPERATING SEQUENCE
1.
For the system compressors to run, all Manual
Reset Cut-outs must be reset, any remote cy-
cling contacts must be closed, the System
Switches must be ON, the Daily Schedule must
be scheduling the chiller to run, and temperature
demand must be present.
2.
As long as power is applied, the Crankcase Heat-
ers will be on and stay on as long as the com-
pressors are not running.
3.
When power is applied to the system, the micro-
processor will start a 2 minute timer. This is the
same timer that prevents an instantaneous start
after a power failure.
4.
At the end of the 2 minute timer, the micropro-
cessor will check for cooling demand as well as
check to see if any system safeties are exceeded.
If all conditions allow for start, the compressor
will start unloaded. Coincident with the start, the
programmable anti-recycle timer will be set and
begin counting downward to “0”. The liquid line
solenoid valve will open when the system is
pumped down to the suction pressure cut-out
(Pumpdown on start-up).
5.
After 4 seconds of run time, the motor current
of the compressor must be >14% FLA and <115%
FLA. Oil pressure must be 5 PSID or greater. If
these conditions are not met, the lead compres-
sor will shut down.
6.
After 30 seconds of run time, the oil pressure
of the compressor must be a minimum of 20 PSID
and the suction pressure must be a minimum of
50% of cut-out.
7.
After 2 minutes and 30 seconds of run time,
the compressor will load, if cooling demand re-
quires.
8.
After 4 minutes or run time, the compressor’s
suction pressure must be greater than the pro-
grammed cut-out. In addition, the oil pressure of
the lead compressor must be greater than 25
PSID.
9.
After 5 minutes of run time, the compressor
will load another step and will continue to load at
150 sec. intervals.
10.
Operation beyond 6 minutes will be dictated by
cooling demand. Anti-recycle timers will time out
and system safety thresholds will contine to be
monitored.
11.
The second compressor will follow the same se-
quence; however, compressors cannot start si-
multaneously. There will always be a 1 minute
delay between compressor starts.
