Buzzing Transformer

[Mike Lamb]

Very loud buzzing from this transformer. What are the usual causes? Loose housing, connections?

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[John Kogel]

EMF, electromotive force, is getting the thing all excited. When transformers buzz, they are usually crying for help, overloaded or something. At least I wouldn't ignore it, as that is a pricey item to replace.

[Marc]

In a power transformer without defects, the loudness of the hum is a result of it's design. They're loud because of a magnetic flux density that comes closer to saturation values and because of the choice of design of the magnetic core. Some transformers are built with fewer windings, while still preserving the turns ratio. Fewer windings saves money but ramps up the magnetic flux density increasing the hum. Noise is a consideration in choosing a design for a particular application. It's in the engineering data, expressed in db. Often times, an electrician will replace a defective transformer with an economy replacement not knowing that the loudness of the hum is one of the specs of the transformer.

Defects that could cause excessive buzzing include shorted turns in the windings and issues involving a discontinuity in the magnetic circuit. Like electricity, magnetic flux has circuits. Both defects manifest with a louder than normal hum, an elevated primary current and excessive temperatures in the primary windings when the transformer is unloaded. They result in reduced transformation efficiency, reduced transformation capacity and a shortened transformer life besides being a noisy nuisance.

Marc

[Erby]

Geeze Marc, speak English. That's written like you copied it from somewhere

But, given your history, I'd bet you just pulled it out of your head from experience.

[Jim Katen]

Translation: Cheap transformers buzz.

[Marc]

Geeze Marc, speak English. That's written like you copied it from somewhere

But, given your history, I'd bet you just pulled it out of your head from experience.

I've a degree in EE. Transformers, all types of electric motors, power generation and analog electronics were my finest points. But to tell you the truth, Jim K dealt with it just as well, but only if the transformer has no defects. That's the question that remains.

Marc

[rkenney]

All of the replies to this thread so far have omitted one important detail. Simple physics reminds me that to have audible 'sound' there must be movement.

Basically the magnetic fields created and collapsed and reversed 60 times a second minutely 'stretch' and 'shrink' the metal parts. This constant movement of parts relative to each other (rub) causes the noise.

The transformer pictured (microwave) has a laminated core, each of the laminations expand and contract at slightly dissimilar rates. As the transformer ages more movement can occur creating more noise.

Consider a transformer with riveted laminations instead of welded and core laminations with less stringent quality controls (thickness differences, metal impurities, etc.) and its easy to imagine greater movement between laminations and more 'buzz" from poor design or construction.

So design and materials are certainly a major factors in minimizing the noise, but age and the physical rigors of operation and environment all contribute to transformer noise.

And that's the rest of the story.

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[Stephen Lagueux]

So, in order to find out for sure, a technician would have to check the sound level with a db meter and compare it to the expected db stated on the data sheet...? I guess the location of the transformer, vibration, the reverberation of the sound and echo can make it sound louder too?

[Marc]

All of the replies to this thread so far have omitted one important detail. Simple physics reminds me that to have audible 'sound' there must be movement.

Basically the magnetic fields created and collapsed and reversed 60 times a second minutely 'stretch' and 'shrink' the metal parts. This constant movement of parts relative to each other (rub) causes the noise.

The transformer pictured (microwave) has a laminated core, each of the laminations expand and contract at slightly dissimilar rates. As the transformer ages more movement can occur creating more noise.

Consider a transformer with riveted laminations instead of welded and core laminations with less stringent quality controls (thickness differences, metal impurities, etc.) and its easy to imagine greater movement between laminations and more 'buzz" from poor design or construction.

So design and materials are certainly a major factors in minimizing the noise, but age and the physical rigors of operation and environment all contribute to transformer noise.

And that's the rest of the story.

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Good Gosh Almighty. Erby's right. Look what I done started. Sorry Fellas.

Marc

[John Kogel]

Consider a transformer with riveted laminations instead of welded and core laminations with less stringent quality controls (thickness differences, metal impurities, etc.) and its easy to imagine greater movement between laminations and more 'buzz" from poor design or construction.

So design and materials are certainly a major factors in minimizing the noise, but age and the physical rigors of operation and environment all contribute to transformer noise.

And that's the rest of the story.

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Good Gosh Almighty. Erby's right. Look what I done started. Sorry Fellas.

Marc

I'll see yer one tranny and raise y'all a box full. []

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[Erby]

With first Marc's stuff and then Bob jumping on the bandwagon to show he knows a few big words too, my head is just spinning.

It's a dizzying kind of day here.

My report:

Cheap or defective transformers buzz. Get an electrician to tell you which one this is and repair / replace as necessary.

[John Kogel]

With first Marc's stuff and then Bob jumping on the bandwagon to show he knows a few big words too, my head is just spinning.

It's a dizzying kind of day here.

My report:

Cheap or defective transformers buzz. Get an electrician to tell you which one this is and repair / replace as necessary.

It could be my fault. I said 'EMF' cuz I couldn't mumember 'flux'. So Marc said 'flux' in a sentence or two. So Bob said .... the rest of the story. []

Condensation in that metal cabinet could be causing corrosion between the steel plates of the core, big word, laminations, but that would only be if the transformer sits idle for some time. Rusty transformer plates can be rescued by careful cleaning and coating with something like varnish. But that would be one visual clue to look for.

[Mike Lamb]

Thanks. These pics are also from my notes.

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[Erby]

Now we're throwing charades in too!

Hooo Boy!

[Marc]

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Look at the primary taps shown in the drawing...If the applied primary voltage is higher than the value indicated in the drawing for the particular taps connected then a louder than normal hum might result, in addition to higher operating temps, etc.

Marc