4.17- Oil pressure control
4.17.1- Oil pressure Setpoint determination
The following algorithm applies to all unit types:
104
86
70
Oil setpoint 1
(kpa)
> 350
240 < AND <350
< 240
Suction pressure (kpa)
Oil Setpoint2 is calculated as follows:
0.63645* (DP - SP) + 35
2* (DP - SP) - 1516
0.235* (DP - SP) + 4
Oil setpoint 2
(kpa)
> 1137
861 < AND < 1137
< 861
DP - SP (kpa)
* DP = Discharge Pressure
* SP = Suction pressure
4.17.2- Oil pump control
The oil pump is generally used to provide pre-lubrification of the compressor. Moreover, it is controlled to insure a
correct oil pressure during capacity transition or during operation with low condensing temperature that cause a drop
of oil pressure to avoid tripping in alarm.
Thus the oil pump is turned ON when the Differential Oil Pressure is lower than Oil Setpoint 1 plus 13 kpa.
and remained ON until Differential Oil Pressure is greater than Oil Setpoint 1 plus 35 kpa AND difference between
discharge and economizer pressure is greater than Oil Setpoint 1 plus 150 kpa to avoid oil pump cycles.
4.17.3- Low Oil pressure alarm determination
ALARM
68 for Compressor A1, ALARM 69 for Compressor A2, ALARM 70 for Compressor B1, ALARM 71 for
Compressor B2.
Criteria For Trip Tested only when the compressor is ON.
DOP: Differential Oil Pressure for the appropriate compressor. DOP = Oil pressure - Economizer pressure.
Economizer pressure is the common (econ_sel = YES) Economizer Pressure transducer reading for the
circuit involved or the appropriate economizer pressure transducer (econ_sel = NO) associated to the
compressor.
A. Compressor has started with Normal Ambient (oat > 10 °C) or or condenser temperature (temp > 18°C)
1.
If the compressor has been running for less than 5 seconds then ignore the alarm.
2.
If the compressor has been running for more than 5 seconds but less than 30 seconds and
DOP < (Oil Setpoint1/30)*(Comp. Running Time [in seconds])
for 3 continuous readings, then the alarm shall be tripped.
3.
If the compressor has been running for 30 seconds or more, then if:
a). DOP < Oil pressure setpoint1 for 15 continuous seconds,
OR
b). (Poil - Psuction) < Oil pressure setpoint2 for 15 continuous seconds,
then the alarm shall be tripped
B. Compressor has started with Low Ambient (oat < 10 °C) or low condenser temperature (temp < 18°C)
1.
If the compressor has been running for less than 90 seconds then ignore the alarm.
CARRIER SA
USER'S GUIDE FOR
30GX&HX PRO_DIALOG 4 V.2
ECG-UG-02-002
Rev: Original
Page: 49/98
©
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ARRIER
S
.
A
NOT
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