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SYMPTOM/CAUSE CHARTS
SYMPTOM/CAUSE charts are generally directed towards the more experienced technician. The intent of these
charts is to provide a range of possible causes for a specific symptom. In doing so, these charts provide a direction,
but with limited instruction.
SYMPTOM POSSIBLE CAUSES
Input line voltage unbalanced
Faulty connection on input wiring
Fault in plant power transformer
Input SCR/Diode module faulty or not being gated.
Open motor winding
Faulty motor connection
Fault in inverter section (see Symptom No. 6.)
7. Unbalanced Input Phase Currents
Note: Slight variations in phase
currents is normal. Variations greater
than 5% require investigation.
8. Unbalanced Motor Phase Currents
Note: Slight variations in phase
currents is normal. Variations greater
than 5% require investigation.