Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
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7.31. Control Power Relay (No Stop)
This feature provides the capability to interrupt the power supply to the system when a particular
compressor continues to draw a specified amperage level when it is called to be OFF. A Relay Output,
referred to as the control relay, must be wired so that no power reaches the compressors when it is
switched OFF. The Relay Output must be selected in the ‘Control Relay’ cell of the General Information
panel of MCS-Config and Setpoint #112 “NO STOP” must be active. The Magnum will continually monitor
the amp draw of compressors that are called to be OFF. If the amp draw is
greater than the FLA for that compressor multiplied by the percentage in
Setpoint #112 “NO STOP” for the time specified in the ’Time (sec)’ field, then
the control relay will turn OFF, a NO STOP alarm will be generated, and the
system will be Locked Out.
7.32. Low and High Ambient Shutdown
The Magnum software supports both low and high ambient temperature shut downs. This option requires
an ambient temperature sensor and one or both of Setpoints #24 “LOW AMB OFF” and #26 “HIGH AMB
OFF”. The AMBIENT OFF state is entered when the ambient temperature falls below the Setpoint #24 or
above Setpoint #26. The system will remain in this state until the ambient temperature rises 5.0F (2.5C)
above Setpoint #24 value or drops 5.0F (2.5C) below Setpoint #25. When the chiller is in this state, the
individual compressor states are changed to the CMP IS OFF state through the normal staging function.
7.33. Imperial, Metric, and Combined Unit sensor readings
The Magnum software supports Imperial, Metric, and Combined unit sensor readings. This setting is
specified in the Setup screen of MCS-Config. All sensor values and all software-coded offsets are
automatically converted to the option selected and displayed with the appropriate character. The following
table contains the display character:
SENSOR READING ENGLISH
CHARACTER
METRIC
CHARACTER
MIXED
CHARACTER
Temperature F C C
Pressure – Gage Reading P B P
Pressure – Absolute Reading p b p
Humidity % % %
Digital or Switch
Amp or CT A A A
Voltage V V V
Refrigeration Level % % %
If the unit type is changed, MCS-Config will give you an option to automatically change the values of all
items in the Setpoints to match the new type and will automatically adjust the display characters.
7.34. Warning and Alarm Relay Outputs
The Warning Relay Output will be turned on whenever the Magnum generates a warning message.
These messages are:
 LOW REFR TEMP UNLOAD
 LOW SUCT PSI UNLOAD
 HIGH DISC TEMP UNLOAD
 LOW SUCT RELOAD
 LOW DISC RELOAD
 CICRUIT IS IN A SAFETY STATE
The system will continue to run since no safeties have tripped. The Warning Relay Output will also be
turned on whenever a compressor is placed in a safety state.
The Alarm Relay Output will be turned on whenever the Magnum generates an alarm message. This
indicates that a safety trip or Lockout has occurred.