Specifications

56
The two setpoints are used by the control for the low oil pressure
alert trip criteria below:
1. Oil Pressure is ignored during the first five seconds after a
compressor is started.
2. In period between 5 and 30 seconds after starting, the alert
will be generated if (Po - Pe) < [(Oil Setpoint 1)/30]* (Compressor
run time in seconds) for 3 consecutive readings.
3. After 30 seconds run time, the alert will be generated if:
a. (Po - Pe) < oil setpoint 1 fot 15 seconds OR
b. (Po - Ps) < oil setpoint 2 fot 15 seconds
Where Pd = Discharge pressure, Ps = Suction pressure, Po = Oil
pressure and Pe = Economizer pressure
NOTE
(Po - Pe) is the Oil pressure differential displayed in <3>
<STAT> for Circuit A and <5> <STAT> for circuit B.
Low oil pressure alert criteria and setpoints
(Alert 40 to 43)
Two oil pressure setpoints are used. Oil setpoint 1 and oil setpoint 2.
Oil setpoint 1 (oil pressure differential Po - Pe) is calculated as
follows:
30HXC
Oil setpoint 1 = 70 kPa if saturated suction pressure ≤ 240 kPa
Oil setpoint 1 = 86 kPa if saturated suction pressure > 240 kPa
but < 450 kPa
Oil setpoint 1 = 100 kPa if saturated suction pressure > 450 kPa.
30GX
Oil setpoint 1 = 70 kPa for all saturated suction pressure
Oil setpoint 2 (oil pressure differential Po - Ps) changes as a
function of the operating conditions (compressor pressure
differential).
The curve below gives the minimum oil pressure differential
corresponding to oil setpoint 2.
10005000 1500 2000
200
400
600
800
1000
1200
1400
Minimum oil pressure vs compressor pressure differential
COMPRESSOR PRESSURE DIFFERENTIAL, Pd - Ps (kPa)
OIL SETPOINT 2
OIL PRESSURE DIFFERENTIAL, Po - Ps (kPa)