Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
149
# Name Description
75 HI AMPS This Setpoint is a percentage of the FLA; it is used to create the high amp draw limit. The
value of this Setpoint is multiplied by the respective compressor’s full load amps Setpoint
(#171 through #190) to obtain its upper limit. If the compressor’s amps exceed this value
for the time specified in this Setpoint, then a safety trip occurs.
76 LO AMPS This Setpoint is a percentage of the FLA; it is used to create the low amp draw limit. The
value of this Setpoint is multiplied by the respective compressor’s full load amps Setpoint
(#171 through #190) to obtain its lower limit. If the compressor’s amps fall below this
value for the time specified in this Setpoint, then a safety trip occurs.
77 LOW SUCTION If active, the Magnum checks for low suction pressure for each running compressor. If suction
pressure is less than this value for the specified period of time, a safety trip occurs.
Refers to ‘Suction Pressure’ column in the Circuit SI screen.
78 LO SUCT UNLD The purpose of this Setpoint is to take corrective action to prevent a low suction pressure
safety trip. For fixed step compressors: If a compressor has more than one step, is fully
loaded, and if the suction pressure is less than the value of Setpoint #77 “LOW
SUCTION” plus the value of this Setpoint, then one step of capacity will be turned off. For
variable step compressors: If a compressor has a suction pressure less than the value of
Setpoint #77 “LOW SUCTION” plus the value of this Setpoint, then the compressor will
be forced to unload. The circuit state will be changed to LO SUCT HOLD, and will remain
in this state for a minimum of the time in Setpoint #101 “SAFETY HOLD DELAY”. At that
time, if the suction pressure has increased greater than the value of Setpoint #77 “LOW
SUCTION” plus the value of Setpoint #79 “LOW SUCT RELD” the compressor will return
to normal control.
79 LOW SUCT RELD Refer to Setpoint #78 description.
80 UNSAFE SUCT If active, the Magnum checks for unsafely low suction pressure for each running compressor.
If suction pressure is less than this value for the specified period of time a lockout occurs
(can configured as a regular safety with automatic reset if ‘Setpoint Type’ is Setpoint
instead of Lockout). NOTE: The time period specified should be very short (2-5 seconds).
If this Setpoint trips, the compressor will be sent straight to the Lockout state.
Refers to ‘Suction Pressure’ column in the Circuit SI screen.
81 HI DISC PSI If active, the Magnum checks for high discharge pressure for each running compressor. If the
discharge pressure sensor reads greater than this Setpoint for the specified period of
time, a safety trip will occur.
Refers to ‘Discharge Pressure’ column in the Circuit SI screen.
82 HI DISC UNLD The purpose of this Setpoint is to take corrective action to prevent a high discharge pressure
safety trip. For fixed step compressors: If a compressor has more than one step, is fully
loaded, and if the discharge pressure is more than the value of Setpoint #81 “HI DISC
PSI” minus the value of this Setpoint, then one step of capacity will be turned off. For
variable step compressors: If a compressor has a discharge pressure more than the
value of Setpoint #81 “HI DISC PSI” minus the value of this Setpoint, then the
compressor will be forced to unload. The circuit state will be changed to HI DISC HOLD,
and will remain in this state for a minimum of the time in Setpoint #101 “SAFETY HOLD
DELAY”. At that time, if the discharge pressure has decreased below than the value of
Setpoint #81 “HI DISC PSI” minus the value of Setpoint #83 “HI DISC RELD” the
compressor will return to normal control.
83 HI DISC RELD Refer to Setpoint #82 description.
84 LO DISC SHEAT If the calculated discharge superheat is less than this value for the specified period of time, a
safety trip will occur. Also, there is an option in the Circuit Base screen to tie a Relay
Output to this Setpoint that will activate whenever a low discharge superheat condition
occurs. A Low Discharge Superheat condition can also put the circuit into a ‘HI DISC
UNLOAD’ state where the compressor will unload to try to raise the superheat.
If economizer is being used, when the discharge superheat goes below the value for the
safety time / 9 the economizer is turned off.
85 LO DISC PSI If active, the Magnum checks for low discharge pressure. If the discharge sensor reading is
less than this value for the specified period of time, a safety trip occurs.