Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
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Specifies if the Fluid Cooler Economizer (if used) can use the condenser fans or VFD.
Control Condenser On:
(Disc PSI) - The Magnum will check for the compressor with the highest discharge and use that as the
controlling pressure.
(Other SI) - The Magnum will not check for the compressor with the highest discharge pressure but will
always use the value of the sensor that is selected as the control.
7.74.3.2. Control Discharge Pressure Calculation
If control is based on discharge pressure, all types of condensers will operate in the following sequence. For
compressors within the same fan bank or suction group, the compressor with the highest discharge pressure will be
held as the control pressure, regardless if the compressors are running or not.
The newly started compressor will have the controlling discharge pressure even if it is not the highest value in
order for it to build pressure (startup mode is defined as the compressor has been on for less than 5 minutes and its
discharge pressure is less than the value of Setpoint #45 “CND STG1 ON” minus the value of Setpoint #47 “CND DIFF
ON”). However, this logic will be overruled if another compressor sharing the same condenser approaches the high
discharge safety (if discharge pressure rises above calculated value of Setpoint #81 “HI DISC PSI” minus #83 “HI
DISC RELOAD”)
If control is based on Other SI, the value of that sensor is always used as the control discharge pressure.
7.74.3.3. Condenser Related Setpoints
The following are Condenser related Setpoints:
45 CND STG1 ON
(RO Type)
When the discharge pressure is above this value, turn on the first stage of the condenser
fans.
‘Time (sec)’ field: (Applies to compressors with shared condensers) If non-zero, then the
compressor in startup state will not be in sole control of the condenser fans, it will control
off of highest discharge pressure. If zero, then compressor in startup will have sole
condenser control for 5 minutes. This option is selected in in the ‘Newly started Comp
Controls Common Fan Bank’ box in the ‘Condenser Information’ panel under the MAG
V8 screen.
46 CND STG1 OFF
(RO Type)
If stage 1 of condenser capacity is on and the discharge pressure drops below this value,
then turn this stage off.
47 CND DIFF ON
(RO Type)
Differential pressure added to Setpoint #45 to set the threshold at which each additional
stage of condenser capacity will turn on.
48 CND DIFF OFF
(RO Type)
Differential pressure added to Setpoint #46 to set the threshold at which each additional
stage of condenser capacity will turn off.
CND ADJ DELAY
(Modulating Type)
If active this is the time in seconds between condenser adjustments to the AO. If inactive,
then 30 seconds will be used as the delay.
If type is DELAY: (required for condenser relay delays).
-MIN VFD Opening cell contains the time delay between turning on a relay and moving
the AO to its minimum position (Setpoint #52).
-MAX VFD Opening cell contains the time delay between turning off a relay and moving
the AO to 100%.
DUAL PSI DELTA
(Dual V8)
Minimum difference in pressure before the second stage of condenser capacity can be
started.
49 CND MIN RUN
(RO Type)
Once a condenser stage has been turned on, it will remain on for at least the amount of
minutes specified in this Setpoint.
DUAL TIME DELAY
(Dual V8)
Time delay once the pressure difference in Setpoint #48 has been reached before the
second condenser stage can be started.