Quantech QTC40160, Installation Operation & Maintenance

Page: 113 / 188

Section 7 - Operation
Quantech
113
Form QTC4-NM2
Issue date: 05/12/2023
7
The following is the status display fault message for
this safety:
SYS X YYYYYYYY LOW MOTOR CURRENT
The X indicates the system and YYYYYYY indicates
the system is in a FAULT condition and will restart
when the 120 s 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 4.48 barg (65 psid). This safety is
ignored for the first 90 s 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 following is the Status display fault message
for this safety:
SYS X YYYYYYYY HIGH DIFF OIL PRESSURE
The X indicates the system and YYYYYYY indicates
the system is in a FAULT condition and will restart
when the 120 s 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
ensures that the compressor is pumping sufficiently to
push oil through the oil cooling circuit and through the
internal compressor lubrication system. The following
is the Status display fault message for this safety:
SYS X YYYYYYYY LOW DIFF OIL PRESSURE
The X indicates the system and YYYYYYY indicates
the system is in a FAULT condition and will restart
when the 120 s 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 s of run time. After
the first 60 s of operation, the cutout is linearly ramped
from 0 barg to 2.09 barg (0 psid to 30 psid) in 5 min
to 10 min based on ambient temperature. See the fol-
lowing table for the ramp times for the given ambient
temperatures.
Table 21 -
Low differential oil pressure cutout
Ambient temperature Ramp time
More than 50ºF (10°C) 5 min
More than 45ºF (7.2°C) 6 min
More than 40ºF (4.4°C) 7 min
More than 35ºF (1.6°C) 8 min
More than 30ºF (1.1°C) 9 min
More than or equal to 30ºF (1.1°C) 10 min
A 30 s safety bypass below 50 Hz is employed dur-
ing rampdown. The bypass is primarily needed under
conditions where another compressor is being brought
on and the running compressor is being ramped down
to 5 Hz to add the additional compressor due to load
requirements. Under these conditions, the slow speed
of the running compressors cause the oil differential to
become very low, especially if the water temperature
is high and the suction pressure is high. The bypass
ensures the compressors 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
121°C (250°F). A system will also be inhibited from
starting if the discharge temperature is above 93°C
(200°F). The following is the Status display fault mes-
sage for this safety:
SYS X YYYYYYYY HIGH DISCHARGE TEMP
The X indicates the system and YYYYYYY indicates
the system is in a “FAULT” condition and will restart
when the 120 s anti-recycle timer times out or “LOCK-
OUT” and will not restart until the operator clears the
fault using the keypad.