Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
159
# Name Description
205 MDP MIN OIL DIFF
(Only HVAC)
If active, MDP logic will be added to EXV control. If the oil differential pressure is less
than the value of this Setpoint following compressor start up during the time
specified in the Sec to Ignore Safety field, then the MDP function is active and will
close the EXV valve to restore the oil differential pressure.
However, the EXV will
not be allowed to go into the MDP logic if the suction pressure is less than Setpoint
#77 “LOW SUCTION” plus the value of Setpoint #79 “LOW SUCT RELD”. The MDP
logic will be exited and go to EXV HOLDING when the suction pressure is less than
the Setpoint #77 “LOW SUCTION” plus the value of Setpoint #78 “LOW SUCT
UNLD”.
The ‘‘Time (sec)” field contains the offset value added to Setpoint #205 value field to
calculate the oil differential pressure for exiting the MDP control. Magnum software
version 8.05S1 and later multiple this value by 10 to add a decimal, so if you enter a
value of 5 in this field the offset is 5.0psi. Prior to 8.05S1 software version you need
to enter the value with 1 assumed decimal place, for example if you wanted an
offset of 5.0psi you need to enter 50 in this field.
The ‘Lockout Delay” field contains the percentage to close the EXV valve when in the
“MDP CLOSE” state. Magnum software version 8.05S1 and later multiple this value
by 10 to add a decimal, so if you enter a value of 2 in this field the adjustment is
2.0%. Prior to 8.05S1 software version you need to enter the value with 1 assumed
decimal place, for example if you wanted an adjustment of 2.0% you need to enter
20 in this field.
The ‘Sec to Ignore Safety’ cell contains the time (in minutes – not seconds) that the
MDP will be active after a compressor is started.
SurgeLoadAdj
(Only CENT)
The adjustment to increase compressor speed when surging is detected.
206 COND HI AMB
If active, standard condenser control on compressor startup logic will be bypassed when
there is a high ambient temperature. If the condenser type is common and the
ambient temperature is above the value of this Setpoint, then the compressor with
the highest discharge pressure will have control of the condenser.
207 UNBAL VOLTS If active, the average of the voltage sensors is calculated. Each individual voltage
sensor is compared to this average and if the difference is greater than the value of
this Setpoint, an alarm is generated and the unit is locked out.
208 LOW SI OFF
(Only HVAC)
FEATURE NOT YET AVAILABLE
If active, the Magnum checks for a Low SI Off sensor for each compressor. The sensor can
be either an analog or digital input, and is specified in the Circuit SI screen. If the Low SI
Off sensor reading is OFF (Digital) or falls below the value of this Setpoint (Analog) for
the specified period of time, the circuit will be disabled. If a digital input, the circuit will be
enabled once the sensor is ON. If an analog input, the circuit will be enabled once the
sensor is greater than this value plus the value in the ‘Time (sec)’ field.
‘Time (sec)’ field: Differential value of this Setpoint which the analog input must be greater
than to enable the compressor.
209 HI SI OFF
(Only HVAC)
(HVAC 08.02E1 or
Greater
Formerly #140)
FEATURE NOT YET AVAILABLE
If active, the Magnum checks for a High SI Off sensor for each compressor. The sensor can
be either an analog or digital input, and is specified in the Circuit SI screen. If the High SI
Off sensor reading is ON (Digital) or rises above the value of this Setpoint (Analog) for
the specified period of time, the circuit will be disabled. If a digital input, the circuit will be
enabled once the sensor is OFF. If an analog input, the circuit will be enabled once the
sensor is less than this value minus the value in the ‘Time (sec)’ field.
‘Time (sec)’ field: Differential value of this Setpoint which the analog input must be less than
to enable the compressor.