Transformer humming 1

[Emad Shaaban]

50kva transformer supplying battery charger system start making a loud humming sound with load and. With noloaf ,transformer insulation resistance is high,but when using scope meter,output currents was distorting any help
Wave form

http://files.engineering.com/getfil...c=212727627.6.1498642837251&__hsfp=2312009246

 

[unclebob]

Battery chargers will inject harmonics in the system. Put your scope meter when the charger is connected. What's the size or number of chargers do you have?

The wave form you sent doesn't show lower harmonics (3,5,7).

 

[Emad Shaaban]

Thank you unclebob
the picture i attached is for out put current when charger was connected.battery charger is 40kva used as UPC

 

[jraef]

Transformer hum is usually from magnetstriction in the core laminations and if the transformer was not designed for non-linear loads, the core laminations are likely getting loose over time. There will not be a lot that you can do about it now short of replacing the transformer with one more suitable for non-linear loads. What you can try is to add rubber isolation mounting pads to try to prevent that from amplifying into the surrounding structure. It might help a little.


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