Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1

The Magnum supports the following options:

 No Condenser - No condenser specified.

 RO Step Common - The highest discharge pressure from any compressor on the system will

be the controlling pressure.

 RO Step Individual - Each compressor will have one or more condenser Relay Outputs

associated with it. The discharge pressure on that compressor will be the control pressure for its

own condenser.

 RO Step Combined - The highest discharge pressure from either of the compressors on the

shared circuits will be the controlling pressure (circuits 1 and 2 are shared, circuits 3 and 4 are

shared, circuits 5 and 6 are shared, and circuits 7 and 8 are shared).

 Modulating Common - The highest discharge pressure from any compressor on the system will

be the controlling pressure. The Analog Output is modulated based on the Rate of Change of the

controlling discharge pressure. It can also be controlled on a selected sensor input.

 Modulating Step Common - This type of condenser has a common fan bank for the system.

The control will be on the systems highest discharge pressure. The Relay Outputs are also

supported along with an Analog Output.

 Modulating Individual - Each compressor will have its own condenser Analog Outputs

associated with it. The Analog Output for each circuit is modulated based on its own discharge

pressure Rate of Change. It can also be controlled on a selected sensor input. You may also

select Relay Outputs to be turned ON/OFF while modulating the Analog Output.

 RO Shared - This type of condenser will take the highest discharge pressure of circuits 1 and 2,

then 2 and 3, then 3 and 4, etc. to use as the control discharge pressure. This condenser type

does not have the option to bypass the startup compressor.

 Dual V8 - This special type of condenser is a common control air condenser with two stages of

fans plus a VFD Fan. Control of the fan speed will be different depending on whether one or two

stages are on. All compressors are in the same fan bank with the highest discharge pressure

being the control.

 Common VFD Fan with Bypass - Three consecutive Relay Outputs, an Analog Output, and a

VFD fault indicator are required to control this type of condenser. RO’s needed:

1) VFD LOAD - This relay will be ON indicating the fan can be used.

2) VFD BYPS - This relay will be OFF unless a VFD fault has occurred.

3) VFD ENAB - This relay will be ON unless a VFD fault has occurred.

During normal operation, VFD LOAD will be on, VFD BYPS will be off, and VFD ENAB will be on. The fan

will be modulated as required by the condenser or economizer logic. If a fault occurs, all relays will be

turned off and the VFD will be set to 0. The Magnum will wait for the time specified in Setpoint #90 “COND

FAULT” before the fan will be run without VFD control if it is needed by the condenser logic (economizer

logic will not function in this condition). Once this time has passed and the condenser logic calls for the

fan, then VFD BYPS will be turned on thereby turning the fan on, however it will NOT be modulated.

The Magnum can also support a variable speed fan for all three of the air type of condensers. Each

compressor can support a variable speed fan. The variable speed must be on the first Relay Output

associated with that compressor.

Note 1: The discharge temperature must be at least 117° F and the discharge superheat needs to be at least 20° F to

guarantee good oil separation.