Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
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Note 2: Condenser staging is critical if the Magnum is to function in different climates. The best option for air-cooled
chillers is to have each fan on its own contactor and a frequency drive on fan 1. This configuration allows the most
optimum control in all weather.
RO Step Condenser Cut In – Out Logic 7.74.1.
The Cut In and Cut Out Logic Setpoints are as follows:
Setpoint #45 “CND STG1 ON” - Condenser stage 1 Cut In (ON).
Setpoint #46 “CND STG1 OFF” - Condenser stage 1 Cut Out (OFF).
Setpoint #47 “CND DIFF ON“ - Cut In differential for additional condenser stages for (ON).
Setpoint #48 “CND DIFF OFF” - Cut Out differential for additional condenser stages (OFF).
Setpoint #49 “CND MIN RUN” - Minimum run time for a condenser stage
Condenser Relay Outputs will be turned on based upon the value in Setpoint #45 “CND STG1 ON”.
When discharge pressure reaches this value, the first condenser Relay Output is turned on. If additional
condenser outputs are present, they will be turned on when the pressure exceeds the cut in value plus the
value contained in Setpoint #47 “CND DIFF ON“. When discharge pressure falls, the condenser outputs
will be turned off based upon the Setpoint #46 “CND STG1 OFF” plus the value contained in Setpoint #48
“CND DIFF OFF”. The first step will be turned off when discharge pressure falls below Setpoint #46 “CND
STG1 OFF”.
Example:
Setpoint #45 “CND STG1 ON” = 200 psi
Setpoint #46 “CND STG1 OFF” = 170 psi
Setpoint #47 “CND DIFF ON” = 20 psi
Setpoint #48 “CND DIFF OFF” = 5 psi
COND FAN 1 ON at 200 psi (Discharge)
COND FAN 1 OFF at 170 psi
COND FAN 2 ON at 220 psi (200 + 20)
COND FAN 2 OFF at 175 psi (175 + 5)
COND FAN 3 ON at 240 psi (220 + 20)
COND FAN 3 OFF at 180 psi (175 + 5)
RO Step Condenser with Variable Speed Fan 7.74.2.
The Setpoints for variable speed fan control are as follows:
Setpoint #54 “CND MIN SPD” - Minimum variable speed allowed.
Setpoint #55 “CND MAX SPD“ - Maximum variable speed allowed.
The purpose of the variable speed fan is to reduce the cycling of the fans by adjusting the speed of the
variable fan point. This control works in conjunction with the Cut In and Cut Out logic of each compressor.
When a fan is turned on, the speed of the variable point for that compressor is set to maximum allowed
percentage. As the discharge pressure falls, the fan speed is adjusted proportionally. When the minimum
is reached the fan will turn off.
Condenser Control 7.74.3.
The Condenser Control logic is run with every pass of the algorithm.
7.74.3.1. Common Terms
Condenser Fan Bank:
Indicates which circuits share common condenser fans or are individually controlled.
Suction Group:
Indicates which circuits share a common suction line.
Fluid Cooler Econo?: