Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
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Variable Step Compressors - Capacity is being held due to high discharge temperature or pressure.
Once the discharge returns to normal operating levels the compressor will return to its normal running
state.
SAFETY TRIPPED (20) 6.2.25.
This state is entered when a safety trip occurs but a lockout is not generated. An alarm is generated but
the system will automatically restart after the delay specified in the corresponding Setpoint. If a second trip
occurs within the time specified in the Setpoint, the compressor will be placed in the CMP LOCKED OUT
state.
LO TMP UNLOAD (21) 6.2.26.
The following two conditions can cause this state to be entered and the system to begin unloading:
1) The leaving liquid temperature is within 1.5°F of the Setpoint #111 “FREEZE “
2) The refrigerant temperature is less than Setpoint #155 “LO REF TMP” if this Setpoint is active.
LO TMP HOLD (22) 6.2.27.
Reload from the “LO TMP UNLOAD” occurs when the leaving liquid temperature is 3.0° F above Setpoint
#111 “FREEZE “and the refrigerant temperature sensor, if present, is greater than Setpoint #155 “LO REF
TMP” plus twice the value of Setpoint #156 “LO REF TMP”. Until this temperature is reached the system
will remain in the LO TMP HOLD State.
HI AMP HOLD (23) 6.2.28.
Fixed step compressors - This state occurs when a fully loaded compressor experiences an abnormally
high amp draw. Refer to Setpoints #171-190 for FLA per compressor (compressors 1-20 respectively)
and #75 “HI AMPS %”. In this state, one step of capacity will be turned off. The compressor will remain in
this state for a minimum of five minutes before returning to the LOADED state if the high amp draw
condition has been corrected.
Variable Step Compressors - This state occurs after HI AMP UNLDING. It will remain in this state for the
time specified in Setpoint #101 “SAFETY HOLD DELAY”. If the amp draw is less than the FLA Setpoint
for this compressor, it will return to the normal operating state and the compressor will be able to load if
necessary. In this state the compressor will not load but it can be unloaded if needed.
HI DIS TMP HLD (24) 6.2.29.
Refer to Setpoints #87 “HI DISC TMP”; #88 “HI DISC UNLD”; and #89 “HI DISC RELD”.
This state is entered when a fully loaded compressor that has more than one step encounters a high
discharge temperature. One step of capacity will be turned off. The compressor will then remain in this
state for a minimum of five minutes before returning to the LOADED state if the high discharge
temperature has returned to normal.
CMP IS AT 40% (25) Only HVAC Software 6.2.30.
For Mitsubishi Screw compressors only. This compressor does not provide variable capacity but has two
solenoids used to regulate the compressor capacity. This state occurs when the compressor is providing
40% capacity. In this state, the Relay Output to activate the 40% valve is turned on.
SURGE SPD/VANE (25) Only CENT Software 6.2.31.
This state is entered when the number of surges has exceeded Setpoint #212 “SurgingCount”. The
Magnum will take preventive action to attempt to avoid a safety trip due to excess surges. The
compressor speed will increase and the vanes closed.
CMP IS AT 70% (26) Only HVAC Software 6.2.32.
For Mitsubishi Screw compressors only. This compressor does not provide variable capacity but has two
solenoids used to regulate the compressor capacity. This state occurs when the compressor is providing
70% capacity. In this state, the Relay Output to activate the 70% valve is turned on.