Troubleshooting guide
MAGNUM VERSION 8 MANUAL REVISION 3.1
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Network Run/Stop – If OFF the system will not run. This input is provided by another system on the
network. It functions in the same matter as the Run/Stop switch.
Emergency Stop – If ON the system will be shut down immediately and will remain disabled until the
switch is OFF.
7.23. Low Suction Unloading and Holding
This option is activated when Setpoint #78 “LO SUCT UNLD” is active. When suction pressure is below
the calculated value of Setpoint #77 “LOW SUCTION“ plus Setpoint #78 “LO SUCT UNLD” for the time
specified in the ‘Time (sec)’ field, the Magnum will turn on the WARNING Relay Output if specified in
MCS-Config and take the following action:
For fixed step compressors: The Magnum will turn off one step of capacity of the compressor(s) with
low suction until all steps except one are unloaded. The circuit state will be LO SUCT HOLD. The
compressor will remain in this state until the capacity control indicates that another step is to be
unloaded or if the suction pressure has returned to normal after the time in Setpoint #101 “SAFETY
HOLD DELAY” has passed.
For variable step compressors: The Magnum will begin unloading the compressor(s) with low suction
until the suction pressure rises above the calculated value. During this time the circuit state is LO
SUCT UNLOAD. Once this pressure has been reached, the circuit state will be LO SUCT HOLD. The
compressor will remain in this state until the capacity control indicates that another step is to be
unloaded or if the suction pressure has returned to normal after the time in Setpoint #101 “SAFETY
HOLD DELAY” has passed.
Normal suction pressure is defined as any value greater than Setpoint #77 “LOW SUCTION” plus
Setpoint #79 “LO SUCT RELD”. Refer to Setpoints #78 and #79 for additional information.
7.24. High Discharge Pressure Unloading and Holding
This option is activated when the Setpoint #82 “HI DISC UNLD” is active. When the discharge pressure is
above the calculated value of Setpoint #81 “HI DISC PSI” minus Setpoint #82 “HI DISC UNLD” for the
time specified in the ‘Time (sec)’ field, the Magnum will turn on the WARNING Relay Output if specified in
MCS-Config and take the following action:
For fixed step compressors: The Magnum will turn off one step of capacity of the compressor(s) with
high discharge until all steps except one are unloaded. The circuit state will be HI DISC HOLD. The
compressor will remain in this state until the capacity control indicates that another step is to be
unloaded or if the discharge pressure has returned to normal after the time in Setpoint #101 “SAFETY
HOLD DELAY” has passed.
For variable step compressors: The Magnum will begin unloading the compressor(s) with high
discharge until the discharge pressure drops below the calculated value. During this time the circuit
state is HI DISC UNLOAD. Once this pressure has been reached, the circuit state will be HI DISC
HOLD. The compressor will remain in this state until the capacity control indicates that another step is
to be unloaded or if the discharge pressure has returned to normal after the time in Setpoint #101
“SAFETY HOLD DELAY” has passed.
Normal discharge pressure is defined as any value less than the calculated value of Setpoint #81 “HI
DISC PSI” minus Setpoint #83 “HI DISC RELD” and greater than Setpoint #85 “LO DISC PSI”. Refer to
Setpoints #82 and #83 for additional information.
7.25. High Discharge Temperature Unloading and Holding
This option is activated when the Setpoint #88 “DISC TMP UNLD” is active. When the discharge
temperature is above the calculated value of Setpoint #87 “HI DISC TMP” minus Setpoint #88 “DISC TMP
UNLD” for the time specified in the ‘Time (sec)’ field, the Magnum will turn on the WARNING Relay
Output if specified in MCS-Config and take the following action:
For fixed step compressors: The Magnum will turn off one step of capacity of the compressor(s) with
high discharge temperature until all steps except one are unloaded. The circuit state will be HI DISC
HOLD. The compressor will remain in this state until the capacity control indicates that another step is