JOHNSON CONTROLS
246
FORM 201.23-NM2
ISSUE DATE: 3/9/2015
SECTION 8 - MICROPANEL
The status display fault message for this safety is
shown below:
SYS X YYYYYYYY LOW MOTOR CURRENT
X indicates the system and YYYYYYY indicates the
system is in a “FAULT” condition and will restart when
the 120 second anti-recycle timer times out or “LOCK-
OUT” and will not restart until the operator clears the
fault using the keypad.
High Differential Oil Pressure Cutout Fault
The High Differential Oil Pressure Cutout protects the
compressor from low oil flow and insufficient lubrica-
tion, possibly from a dirty oil filter. A system will fault
and shut down with a controlled ramped shutdown
when its Discharge to Oil Differential Pressure rises
above the cutout of 65 PSID. This safety is ignored
for the first 90 seconds of run time. This safety mea-
sures the pressure differential between discharge and
oil pressure, which is the pressure drop across the oil
filter. The Status display fault message for this safety
is shown below:
SYS X YYYYYYYY HIGH DIFF OIL PRESSURE
X indicates the system and YYYYYYY indicates the
system is in a “FAULT” condition and will restart when
the 120 second anti-recycle timer times out or “LOCK-
OUT” and will not restart until the operator clears the
fault using the keypad.
Low Differential Oil Pressure Cutout Fault
The Low Differential Oil Pressure Cutout protects the
compressor from low oil flow and insufficient lubrica-
tion. A system will fault and shut down with a controlled
ramped shutdown when it’s differential between oil
and suction pressure falls below the cutout. This safety
assures that the compressor is pumping sufficiently to
push oil through the oil cooling circuit and through the
internal compressor lubrication system. The Status dis-
play fault message for this safety is shown below:
SYS X YYYYYYYY LOW DIFF OIL PRESSURE
X indicates the system and YYYYYYY indicates the
system is in a “FAULT” condition and will restart when
the 120 second anti-recycle timer times out or “LOCK-
OUT” and will not restart until the operator clears the
fault using the keypad.
The safety is ignored for the first 60 seconds of run
time. After the first 60 seconds of operation, the cutout
is linearly ramped from 0 PSID to 30 PSID in 5 to 10
minutes based on ambient temperature. See Table 13
on page 246 for the ramp times for the given ambient
temperatures.
TABLE 13 - LOW DIFFERENTIAL OIL PRESSURE
CUTOUT
AMBIENT TEMPERATURE
RAMP
TIME
> 50ºF 5 Minutes
> 45ºF 6 Minutes
> 40ºF 7 Minutes
> 35ºF 8 Minutes
> 30ºF 9 Minutes
>=30ºF 10 Minutes
A 30 second safety bypass below 50 Hertz is employed
during rampdown. The bypass is primarily needed
under conditions where another compressor is be-
ing brought on and the running compressor is being
ramped down to 5 Hertz to add the additional compres-
sor due to load requirements. Under these conditions,
the slow speed of the running compressor(s) causes the
oil differential to become very low, especially if the
water temperature is high and the suction pressure is
high. The bypass assures the compressor(s) will not
trip on a nuisance low oil differential fault.
High Discharge Temperature Cutout Fault
The High Discharge Temperature Cutout protects the
motor and compressor from overheating. A system will
fault and shut down with a controlled ramped shutdown
when its Discharge Temperature rises above 250°F. A
system will also be inhibited from starting if the dis-
charge temperature is above 200°F. The Status display
fault message for this safety is shown below:
SYS X YYYYYYYY HIGH DSCHARGE TEMP
X indicates the system and YYYYYYY indicates the
system is in a “FAULT” condition and will restart when
the 120 second anti-recycle timer times out or “LOCK-
OUT” and will not restart until the operator clears the
fault using the keypad.
High Oil Temperature Cutout Fault
The High Oil Temperature Cutout protects the com-
pressor from insufficient lubrication. A system will
fault and shut down with a controlled ramped shutdown
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