We once had a large pump matched with a supporting motor, which suffered from serious abnormal vibration during operation.

Our maintenance staff tried all methods but failed to eliminate the fault completely. Later we invited a professional company to carry out vibration detection and analysis on the equipment.

The final test result surprised everyone: the vibration was not triggered by any mechanical failure at all. The real cause belonged to an electrical fault — one phase of the three-phase power supply was out of balance.

After we notified the local power utility company, they adjusted the transformer taps. Right after the adjustment was finished, the severe vibration vanished instantly.

Most mechanics tend to judge motor vibration issues as bearing damage, misalignment or other mechanical problems at first glance. Cases caused by unstable grid power are always easily overlooked.

I want to ask all industrial maintenance engineers and pump practitioners here:

Have you ever encountered similar faults induced by unbalanced three-phase voltage? What is your standard troubleshooting sequence for pump vibration? Welcome to share your practical experience in the comment section.