Fault display Type Enable Potential causes and corrective actions
Line over voltage fault F SOP Cause
The drive-input RMS voltage is greater than 120% of the drive rated input
voltage.
Action
Use a voltmeter to verify that the input voltages VIA, VIB, VIC are the
expected value for the rated voltage:
• NXGpro test point board: VIA, VIB, VIC values greater than 4.56 Vrms
will trigger an alarm or trip, depending on the SOP.
Note: This fault will cause an input protection fault if dedicated I/O is used
for IP faults.
Medium voltage low 1 A SOP Cause
The drive-input RMS voltage is less than 90% of the drive rated input volt‐
age.
Action
Use a voltmeter to verify that the input voltages VIA, VIB, VIC are the
expected value for rated voltage:
• NXGpro test point board: VIA, VIB, VIC values less than 3.4 Vrms (90%
of rated) will trigger medium voltage low conditions.
Note: This alarm can be caused by a transient condition, and may not be
present when making the measurements.
Medium voltage low 2 A Fixed Cause
The drive-input RMS voltage is less than 70% of the drive rated input volt‐
age.
Action
Use a voltmeter to verify that the input voltages VIA, VIB, VIC are the
expected value for the rated voltage:
• NXGpro test point board: VIA, VIB, VIC values less than 2.66 Vrms will
trigger medium voltage low conditions.
Medium voltage low Flt F Fixed Cause
The drive-input RMS voltage is less than 60% of the drive rated input volt‐
age.
Note: The fault will not occur, even after the threshold condition is met,
until the rst cell fault occurs. This fault is then logged and associated cell
faults ignored.
Action
Use a voltmeter to verify that the input voltages VIA, VIB, VIC are the
expected value for the rated voltage:
• NXGpro test point board: VIA, VIB, VIC values less than 2.28 Vrms will
trigger medium voltage low conditions.
Input one cycle
or
excessive input reactive cur‐
rent
F/A Fixed Cause
Possible fault on the secondary side of the transformer.
Action
1. Remove medium voltage and visually inspect all the cells and their
connections to the transformer secondary.
2. Contact Siemens customer service.
Note: This fault will cause an input protection fault if dedicated I/O is used
for IP faults.
Troubleshooting Faults and Alarms
11.4 Drive Faults and Alarms Input Line Disturbance
NXGPro+ Control Manual
446 Operating Manual, A5E50491925A