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Old 12-20-2016, 09:02 AM   #1
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Default Step down transformer

I have this 112.5 step down which is making a horrible noise. can anyone tell me why it doesn't let me attach a video.
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Old 12-20-2016, 09:38 AM   #2
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post a video

what kind of noise?

If its a vibration type noise, you usually can't do anything unless its the transformer enclosure or at electrical connection points. You can tight up the associated fasteners to fix this.

If the noise is caused by the laminates moving back and forth or caused by the shims in the winding being loose, there is not much u can do.

If its nonlinear load related noise, the 3rd harmonic will circulate in the Delta side of the transformer and cause excess vibration which makes noise. They do make K rated transformer that handle nonlinear loads better. Alot of older transformers are not K rated.

Dry transformers are usually good or bad, not very often are they in the middle of going bad like oil transformers.

Make sure all the electrical connections are tight before you do anything.
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Old 12-20-2016, 10:14 AM   #3
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The bolts that attach the iron core to the frame need to be loosened a bit. They are tight for shipping and if left tight they will transmit noise.

Some transformers (most notably GE) are more noisy than others.
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Old 12-20-2016, 12:18 PM   #4
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Some transformers are just noisy. For the love of god don't put a box around it to try to cut down on the noise.
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Old 12-20-2016, 01:06 PM   #5
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What type of loads? High harmonic currents will absolutely cause a lot of additional iron vibration and make a transformer noisy as hell.

Transformers that only run large VFD loads often sound terrible for just this reason.
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Old 12-20-2016, 06:39 PM   #6
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Transformers that make excessive noise, I mean really loud, may have the laminations delaminating.

Time for replacement, if that is the case.

Check load types as noted above, see if any new loads were added.
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Old 12-20-2016, 07:38 PM   #7
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i still cant upload my video i took on my iphone so its basically the same humming noise you would expect to hear from a transformer but just really load. additionally there is a balanced load of about 20A primary side and the transformer is really hot. is that info helpful?
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Old 12-20-2016, 07:47 PM   #8
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Quote:
Originally Posted by Julius793 View Post
i still cant upload my video i took on my iphone so its basically the same humming noise you would expect to hear from a transformer but just really load. additionally there is a balanced load of about 20A primary side and the transformer is really hot. is that info helpful?
20 amp on primary side on 112.5 Kva transfomer ??

The room is hot then you will expect the transfomer to be hot of course.

Most transfomer can handle pretty high tempture rise without much issues.,,

What type of load it is running thru the transfomer ?

as other poster here gave ya the answer so double check the connection and ya the mounting bolt sometime some peoples forget to remove or loosen up the shipping bolt that useally most common curpit.


You can reduce the noise by putting a rubbber pads below the transfomer unless it is wall hung type which I dont see often on that large a transfomer.

some case you may have to put in a flexi conduit to reduce the noise too.
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Old 12-20-2016, 08:10 PM   #9
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How good is the ammeter you're using? Do the readings make sense proportionately on primary and secondary?

20A is nothing, even if it were all harmonics I wouldn't expect that to be able to heat a 112kVA transformer.
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Old 12-20-2016, 08:38 PM   #10
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i still cant upload my video i took on my iphone so its basically the same humming noise you would expect to hear from a transformer but just really load. additionally there is a balanced load of about 20A primary side and the transformer is really hot. is that info helpful?
Assuming your testing is correct and the noise is truly excessive

See my post above.
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Old 12-20-2016, 09:01 PM   #11
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Assuming your testing is correct and the noise is truly excessive

See my post above.
Yes I think replacement is where we will end up. Thanks
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Old 12-21-2016, 02:26 AM   #12
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I have this 112.5 step down which is making a horrible noise. can anyone tell me why it doesn't let me attach a video.

Usually means something is loose.
or you have shorted turns.
Can you get to the tranny internals ?
or is it a sealed unit ?

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