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Posted By Topic: Switchboard Humming

bonesyhead
Mar 02 2020 17:56

Hi, I have been asked to investigate a loud humming from a large switchboard. This switchboard generally has a constant hum about it given approx 900A per phase load. But, now and then, as reported by on site 24/7 engineers, the hum increases substantially with no increase of load. Anybody come across this before?
   

SaintAlan
Mar 02 2020 20:59

Have you got variable speed drives or thyristor equipment? The harmonics can really rattle some components if they hit resonance.
   

ppaw1965
Mar 02 2020 22:30

Could also be a contactor. Or something else in the plant causing a vibration and something loose or just touching in the board.
   

bonesyhead
Mar 03 2020 10:38

Definitely throughout the building there are a number of VSD's. The hum i can accept as is the case with most big switchboards, but the elevated level of hum periodically has me a bit stumped. Thanks for the idea of VSD's, that could be a contributor.