Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
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available options, it may not necessarily follow the first stage relay. Refer to section 12 for Relay Output
order and options.
The first stage will be turned on if either the discharge temperature is greater than Setpoint #8 or suction
pressure is less than Setpoint #80 plus 5 psi (.5 Bar). If 2 Stage, the second relay will be turned on if the
discharge temperature is greater than Setpoint #8 plus 5.0° F (2.5° C) and the first relay has been on for a
time greater that the ‘Time (sec)’ field of this Setpoint. If the Slide Multiplier cell of the Relay Output for the
first stage of liquid injection is non-zero, then this relay will be turned on during the fast unload logic.
7.19. Oil Cooler Option
The oil cooler option can be enabled for compressors with oil. This feature requires an oil seal
temperature sensor, a Relay Output to energize the oil cooler, and Setpoint #145 “OIL COOLER ON“ to
be active. If the oil seal temperature is above Setpoint #145 for longer than the time specified, the oil
cooler is energized until the temperature is 5° F below the Setpoint value. Refer to section 12 for Relay
Output order and options.
7.20. Oil Pump Control Option
The Magnum supports 3 different types of oil pump control. This option is selected in in the ‘Control of Oil Pump’ box in
the ‘Compressor Information’ panel under the MAG V8 screen.
 OIL PUMP ALWAYS ON – The oil pump will start before the compressor to build up oil pressure and
will always be on when the associated compressor is on. If the oil pressure drops below Setpoint #74
“OIL PUMP OFF”, then shut down the associated compressor and generate a LOW DIFFERENTIAL
alarm. The oil pump will continue running after the compressor is turned off regardless of the reason,
for the time specified in Setpoint #62 “PUMP DOWN DELAY”.
 OIL PUMP CYCLES AS NEEDED – After the compressor has been running for 2 minutes and when
the differential pressure (discharge pressure minus suction pressure) is greater than Setpoint #74
“OIL PUMP OFF”, then the oil pump will be turned off. If the differential pressure drops 10 PSI below
the value of Setpoint #74, then the oil pump will be turned on again.
 OIL PUMP LUBE ONLY – After the compressor has been running for 2 minutes and when the
differential pressure (discharge pressure minus the suction pressure) is greater than Setpoint #74
“OIL PUMP OFF”, then the oil pump will be turned off. If the differential pressure has not reached
Setpoint #74 after 5 minutes, then shut down the associated compressor and generate a LOW
DIFFERENTIAL alarm. If the differential pressure has been reached and the oil pump turned off, then
if the differential pressure drops 5 psi below the value of Setpoint #74, shut down the associated
compressor and generate a LOW DIFFERENTIAL alarm.
7.21. Oil Differential Calculation
For chillers with external oil pumps: Oil Differential = Oil Pressure - Discharge Pressure
For all others: Oil Differential = Oil Pressure - Suction Pressure
If an oil pressure sensor is not available, then discharge pressure can be used in place of it. This is set up
in the Circuit SI screen of MCS-Config by selecting the discharge pressure sensor in the oil pressure
sensor’s column.
7.22. On/Off Switches
The following digital inputs can affect the entire package or individual circuits:
 Flow switch – If OFF the system has no flow. The system will Lockout (if Setpoint #105 is active), or
shut down (if Setpoint #105 is inactive).
 Pump down – If ON and the compressor is off, the compressor will not be allowed to start. If the
compressor is on, the system moves to the Pump Down state to begin turning off the compressor(s)
in normal steps.
 Run/Stop – If OFF the system will not run. If the system is running, the system turns all compressors
off in normal steps (If a RUN/STOP and a Network RUN/STOP are both available they operate in
series).