Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
67
50% × 35% = 17.5%
Current EXV position (35%) + EXV adjustment (17.5%) = New EXV position (42.5%)
35% +17.5% = 42.5%
Therefore the final EXV valve position would be 42.5%
This same calculation will be repeated every time a new stage of capacity is turned on. Conversely, when the unit is
unloading, the EXV adjustment will be subtracted from the current EXV position for every step that turns off. Assume
the EXV is at 40% and the compressor is at 100% and is ready to unload a step (turning on Unload 75% solenoid).
‘EXV Unld Adjust’ column (30%)× current EXV position (40%)= EXV adjustment (12%)
30% × 40% = 12%
Current EXV position (40%) - EXV adjustment (12%) = New EXV position (28%)
40% - 12% = 28%
Therefore the final EXV valve position would be 28%
The values given in the example are only start points. You will need to adjust the values for your system. The idea is to
jump the EXV position so that the superheat would still be above the target slightly, and then the EXV control logic
would then adjust the value to achieve the target superheat. We do not want to open the EXV valve too much when
loading or close the valve too much when unloading so we do not cause low superheat or liquid flooding to the
compressor.
7.44. New Setpoint Functions (08.00-A)
The following features have been added to provide additional flexibility in starting and fine-tuning a system.
Three new fields have been added to each Setpoint:
Sec. to Ignore Safety: Time delay that the safety will be ignored upon compressor startup.
Window to Extend Safety Time: The amount of time after compressor startup (or “Sec to Ignore
Safety” if used) in which the “Safety Time Extension” field is added to the ”Time (sec)” field.
Safety Time Extension: The amount of time added to the “Time (sec)” field during the “Window to
Extend Safety Time”.
Four new Setpoints have been added to provide flexibility:
Setpoint #191, TEMP DIFF
Setpoint #192, FRZ TEMP DIFF
Setpoint #193, TE PSI DIFF
Setpoint #194, PSI DIFF
Eight new EXV related Setpoint have been added to provide flexibility:
Setpoint #65, EXV ZONE1
Setpoint #66, EXV ZONE2
Setpoint #67, EXV ROC ZONE
Setpoint #68, EXV ROC ZONE1
Setpoint #69, EXV ROC ZONE2
Setpoint #70, EXV ROC ZONE3
Setpoint #71, EXV TOO FAST
Setpoint #72, EXV CHANGING
Refer to their definitions in the Setpoints section for a complete description.
7.45. Voltage Sensor (08.00-R)
Up to three sensors that measure voltage input can be specified. If used, a safety condition based upon
Setpoint #195 LOW VOLTAGE and Setpoint #196 HI VOLTAGE will be checked. If a safety trip occurs
the unit will be placed in a safety hold state.