On 24/01/2019 02:14, Peter Jason wrote:
4-pole 3Ph squirrel -cage motor noisy.

A loud buzzing noise has developed over the past
12 months. The motor is not overheating, nor are
the bearings.

Is this serious?
Peter


Is it being powered by clean sine 50/60 Hz or some sort of dirty
chopped/synthesised 3 phase via a converter?