119
YORK INTERNATIONAL
FORM 150.52-NM2 (1001)
Low Oil Temperature Inhibit:
The Low Oil Temperature Inhibit prevents the com-
pressor from starting if its oil temperature is too low
due to heater failure or insufficient time for the heater
to remove refrigerant from the oil. This prevents dam-
age to the compressor. The oil temperature must be
greater than or equal to ambient temperature plus 8°C
(15°F) to allow a compressor to start. If the oil tem-
perature is less than ambient plus 8°C (15°F), the af-
fected system’s compressor will not be allowed to start.
The low oil temperature inhibit can only prevent a com-
pressor start. It is not a safety and will not shut down a
compressor that is running. The inhibit is not logged to
the History buffer.
2.7 SYSTEM FAULT (SAFETY)
STATUS MESSAGES (MANUAL RESET)
A System fault will shut the affected system down when-
ever a preset 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 time period, the
affected system will shut down and lock out on the last
fault. When one or more systems are shut down on one
of these safeties, a message will appear on the Status
display informing the operator of the problem.
The High Motor Current Safety is a
unique safety which will lock out a sys-
tem 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 (see Section 1.11, Fig. 36 for switch
locations).
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 expensive
damage to the system.
High Discharge Pressure Cutout:
The Discharge Pressure Safety prevents system pres-
sure from exceeding safe working limits. This safety is
a backup for the mechanical High Pressure Cutout in
each system. The Discharge Pressure Safety is pro-
grammable for a range of values below the system up-
per limit (see Section 9 [8.2] / page 143, High Dis-
charge Pressure Cutout for more details).
Low Oil Pressure Cutout:
The Low Oil Pressure Safety ensures that the com-
pressor receives proper lubrication by monitoring the
differential between oil pressure and suction pressure
(Oil – Suction = Differential).
The oil pressure cutout is linearly ramped from 0PSID
to 25PSID in 60 seconds. The cutout is totally ignored
for the first 4 seconds of operations. The cutout can be
calculated as follows:
Cutout =
25
(60/Run Time)
High Oil Temperature Cutout:
This safety assures oil temperature does not exceed a
safe operating temperature which affects compressor
lubrication. Typical oil temperature during normal op-
eration will be approximately 48.9 - 60°C (120 - 140°F).
A system will not start up, or will shut down, when its
oil temperature rises above 180°F during the first minute
of run time, or 160°F after the first minute of run time.
Low Suction Pressure Cutout:
The Low Suction Pressure Cutout aids in protecting
the evaporator from damage due to ice build up caused
by operation at low refrigerant charge or restricted re-
SYS 1 LOW OI L TEMP
SYS 2 LOW OI L TEMP
SYS # LOW OI L PRESS
SYS # LOW OI L PRESS
SYS # H I GH DSCH PRES
SYS # H I GH DSCH PRES
SYS # LOW SUCT PRESS
SYS # LOW SUCT PRESS
SYS # HIGH OIL TEMP
SYS # HIGH OIL TEMP
9
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