YORK INTERNATIONAL
44
FORM 201.25-NM1 (302)
Micropanel
Closing of the flow switch, when flow is present, will cause
the message to disappear and auto-restart to occur.
Never bypass a flow switch. This will
cause damage to the chiller and void
any warranties.
3.6 SYSTEM FAULT STATUS MESSAGES
System faults will shut the affected system down when-
ever a pre-set safety threshold is exceeded for 3 sec-
onds. Automatic restart will occur after the first 2 shut-
downs when the anti-recycle timer times out and tem-
perature demand exists.
After any combination of 3 Manual Reset Safeties in a
90 minute period, the affected system will shutdown
and lock out on the last fault. When one or more sys-
tems are shutdown on one of these safeties, a message
will appear on the ‘STATUS’ display informing the op-
erator of the problem.
The High Motor Current Safety is a
unique safety which will lock-out a
system after only a single fault.
To reset a locked-out system, turn the system switch
for the affected system to the ‘OFF’ position, then back
to the ‘ON’ position.
Before returning a locked-out system
to service, a thorough investigation of
the cause of the fault should be made.
Failure to repair the cause of the fault
while manually allowing repetitive re-
starts may cause further damage to the
system.
High Discharge Pressure Cutout:
This cutout prevents system pressure from exceeding
safe working limits. This safety is a backup for the me-
chanical High Pressure Cutout in each system.
The cutout is programmable for a range of values be-
low the system upper limit.
High Discharge Temperature Cutout:
This cutout protects the compressor rotors from dam-
age due to overheating, expansion, and breakdown of
the oil film seal between the rotors. It also protects
against excessive oil temperature in the discharge oil
separator.
For the first 4 seconds of operation discharge tempera-
ture is ignored. After 4 seconds of operation the com-
pressor will shutdown if the discharge temperature ex-
ceeds 260°F (127°C).
High Oil Differential Pressure Cutout:
This cutout protects the compressors against loss of
proper lubrication due to oil return line blockage.
The ‘differential oil pressure’ for this cutout is calcu-
lated by measuring discharge (oil separator) pressure
and subtracting oil pressure returning to the compres-
sor (Discharge - Oil = Oil bar D).
Under typical operation, the oil pressure differential dis-
play will read less than 25 psi (1.7 bar). If oil pressure at
the compressor drops due to filter blockage, the differ-
ential pressure on the display will increase and when the
maximum limit is reached the compressor will be shut-
down.
This cutout is activated after 3 minutes of operation.
Oil pressure must be less than 64 psi (4.4 bar) as long
as the compressor continues to run.
Low Oil Differential Pressure Cutout:
The cutout assures the compressor receives proper lu-
brication by monitoring the differential between oil pres-
sure returning to the compressor and suction pressure.
Lack of a differential indicates that the compressor is
not pumping or low condenser pressure and no oil is
being pumped through the compressor to lubricate the
bearings and rotors.
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