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Quiet type transformers #24784 04/23/03 06:54 PM
Joined: Apr 2001
Posts: 109
njelectricmaster Offline OP
Hello From South Dakota!!!

Hey Guys I have a Question.

We installed a "quiet type" transformer, and needless to say IT IS NOT QUIET!

I crawled back in to it this afternoon and made sure all the conections were tight, the rubber pads were all in place, and all the bolts had been loosened up on the bottom. I double checked the flex connectors on both pieces of flex, and even used a magnet to sweep for loose material.

I am totally stumped. Any of you run into this before?



Jon Niemeyer
Work Gear for Electricians and the Trades
Re: Quiet type transformers #24785 04/23/03 08:16 PM
Joined: Jul 2002
Posts: 8,379
Trumpy Offline
Wouldn't by any chance be a loose transformer lamination?.
Just an idea.
Also, was the transformer energised while you were tightening the mounting bolts?.
Sometimes the hum will just disappear, while doing up the nuts. [Linked Image]

Re: Quiet type transformers #24786 04/23/03 08:20 PM
Joined: Apr 2002
Posts: 2,527
Bjarney Offline
There is some general information at
{Note this is not FPE—the “breaker” guys}

If the transformer has a harmonic-current [a/k/a "nonlinear"] load, acoustic noise may increase.

Re: Quiet type transformers #24787 04/27/03 06:36 PM
Joined: Apr 2001
Posts: 109
njelectricmaster Offline OP
Hello from South Dakota!!!!

Bjarney- Thank you for the links, they were informitive to say the least.

Trumpy- I tried to tighten the shiping bolts back up a little but it did not have any effect. I am at the point were I think you are right about the loose laminations.

Are there any other suggestions? If it is just the laminations is there anything I can do in the field or do I need to replace the transformer?

Jon Niemeyer
Re: Quiet type transformers #24788 04/28/03 01:14 AM
Joined: Feb 2003
Posts: 939
frenchelectrican Offline
about the lamations on the transfomer if that is welded my best is to replace it other wise if that is bolted then you can tighten it down some more but do not go over the torque value and i have bad transformer before i just end up replace it with diffrent model and slove the probem and what size the transformer is ??? i know few transformer will humm at cereten level i am not sure excat number is but it is listed in transformer catalog book i will get the list soon in my office tmw it should be not really loud at all but what other load you have on it it can make a diffrence with it

merci marc

Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)

Re: Quiet type transformers #24789 04/28/03 01:32 AM
Joined: Jul 2002
Posts: 8,379
Trumpy Offline
If you've got a crook lamination in the transformer, it's probably best to replace it, as you may find over time, Eddy currents in the core, will make the situation worse and the hum will worsen.
Is this tranny still under warranty?, if so send it back to the manufacturer and get a replacement, transformers shouldn't do this really!. [Linked Image]

Re: Quiet type transformers #24790 04/28/03 08:48 AM
Joined: Mar 2003
Posts: 36
US Coreman Offline
In our facility, we had a couple 2000 kVA 4160 to 480Y/277V 3 Ph transformers that were purchased as replacements for the original GE units that had failed previously. This all took place years before I arrived. I put in place a PM program where we checked Megger readings, and took Turns Ratio Tests. The loud units checked out fine, they just "sang" louder than most. The NETA guy said that they were just "cheaply made". They continued to perform for years. One even worked fine after being single phased by the utility for an hour during an ice storm. Subsequent testing showed that other than 1 shorted turn in 1 coil of 1 secondary, it was OK. A couple of years ago, we got all new primary distribution, and new unit subs. Now everything is CH/Westinghouse and all is good. Your situation would appear to be different in that you supplied this unit [??], and it may be in your best interests as a contractor to change this unit out.

As an aisde, whenever possible, we try to purchase "Cast Coil" transformers as they are VERY quiet, and fairly impervious to many things. we have them from .25 to 2500 kVA. Only problem, $$$ and their weight.


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