|
,
Diagnose and Prevent VFD Failures
This white paper explains how even small amounts of voltage unbalance can degrade variable-frequency drives (VFDs). While VFDs are built on advanced power electronics, their six-pulse diode bridge rectifiers remain vulnerable to unequal phase voltages. Just a few percent of unbalance is enough to distort current sharing, increase ripple, shorten lifetime of diodes, capacitors, inverters, and ultimately the motor itself. Left unaddressed, these stresses shorten drive life, cause nuisance trips, and compromise reliability in critical applications.
Key topics include:
- How phase voltage disparity leads to diode thermal runaway and capacitor heating
- Ripple current escalation and its impact on DC-link life expectancy
- Motor damage pathways including over-voltage spikes, insulation stress
- Harmonic side effects: triplen harmonics
- Monitoring strategies using PMI Revolution, Seeker, and Bolt recorders to pinpoint unbalance issues
Why utilities should care:
Voltage unbalance may seem minor, but its consequences are major—reduced motor life, unexpected downtime, and costly equipment replacements. With high-resolution waveform capture and advanced analytics in PMI PQCanvass and ProVision software, engineers can distinguish whether a drive is the victim or the culprit, identify imbalance sources, and apply corrective measures such as load redistribution, line reactors, or filtering. Early detection and proactive maintenance can stop this “silent killer” before it escalates into costly failures.
You may also enjoy...
