buzzing (very loud) transformer

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A very old (1969) dry type transformer buzzing loudly. No harmonics or inbalance present, only a low (70 percent) pf. What could be causes? Thanks
 

Jraef

Moderator, OTD
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Electrical Engineer
If it wasn't buzzing and it started to, it could be some problems with the lamination inside the core, i.e. the stack bolts (or clamps, depending on size) are getting loose from repeated overloading or other stresses. Not common, but it happens. Not much can be done about it in the field, you would have to send it off to a service shop.
 

BJ Conner

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Rubber Pads??

Rubber Pads??

A very old (1969) dry type transformer buzzing loudly. No harmonics or inbalance present, only a low (70 percent) pf. What could be causes? Thanks

Where and how is it mounted? It may have rubber or similar material used to mount the core to the frame. Not lilely on samller transformers.
IF it's setting on the "right kind" of floor or wall it can be generting harmonic noise in the structure. If so some rubber isolation mounts may help.

I had a job to look at a 1000 KVA transformer that was roof mounted and was ( and had been ) making noise for years. The owner was remodeling and was going to put office space under the transfromer. The transfomrer was designed with rubber blocks between the core and the housing/support steel. It also had shipping bolts that held the core down tight to the frame to keep it from movingduring shipping. The bolts were still in place. We had to shut it down and removed the bolts. Quited down right away. The shipping bolts had helped get the sound down into the building making it sound even worse.
 

broadgage

Senior Member
Location
London, England
Exessive noise from dry type transformers is sometimes not from the transformer itself, but from the cover/access panels/gaurds vibrating.
This can often be cured by removing the offending parts and re-fixing with rubber washers etc.
You will probably have to isolate the transformer to do this safely.

Another possibility is loose nuts, bolts or washers that have fallen into the transformer. Remove urgently as they may cause a short.
 

RoberteFuhr

Member
Location
Covington, WA.
Make sure that the shipping bolts have been loosened or removed. GE transformers sometimes are shipping with shipping bolts that securely hold the core and coils to the transformer frame. If you do not loosen these shipping bolts, the transformer will vibrate loudly.

Another cause could be harmonics. Harmonics from computers and other electronic devices can cause the transformer to vibrate louder than normal. Another indication of harmonics is if the transformer is running hot. Can you hold your hand on top of the transformer for more than five seconds? If not, then it may be running too hot as well as being loud. It may be time to replace the transformer with a new K rated model capable of tolerating harmonic curents.
 

Besoeker

Senior Member
Location
UK
A very old (1969) dry type transformer buzzing loudly. No harmonics or inbalance present, only a low (70 percent) pf. What could be causes? Thanks
Loose laminations, loose windings..in fact almost anything loose that can vibrate at power frequency.
 
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