500 Hz power transformer noise

[hhhansen]

I have performed a number of noise recordings for a 20 MVA 132/50 kV transformer, ONAN.

As expected there is a 100 Hz component and multipla of this 100+n*100 Hz due to magnetostriction etc.

However I detect a very huge 500 Hz noise component in the noise frequency spectrum. I have cross validated measurements with a consulting engineering company and they made the same conclusion regarding a dominant 500 Hz component.

This must be a symptom of something particular problem for the transformer but what??.
I have made a lot of noise recordings on similar transformers and I have never experienced a very dominant 500 Hz sound like this


Regards
Hans-Henrik

 

[prc]

Are you sure whether this 500 Hz component is from the core? Other vibrating fixtures on transformers also may give out noise, sometimes with a resonance frequency.

 

[cranky108]

First, what is the system frequency where you are located?

 

[hhhansen]

The system frequency is 50 Hz.
The 500 Hz noise is coming from internal of the transformer from my opinion. There are no loose parts exterior causing resonance

 

[FPelec]

I would have also said that it was the fault of loose metal components/accessories on the tank, as suggested by prc; otherwise, the only thing that comes to mind is the presence of a very strong 5th harmonic in the load current.

 

[hhhansen]

The noise records have been made for an unloaded transformer.

 

[edison123]

If it is a new one or recently serviced, core clamp structure became loose and is resonating at some weird freq? Or worse, some tools were left and are dancing around due to magnetostriction ?



Muthu

http://www.edison.co.in

 

[oldrunner]

If it is a core clamping issue or a windings clamping issue, do you know if the clamping system on the windings has some sort of a hydraulic compression system? The coil stack column may have shrunk due to degradation and now is loose. Helpful if we know the age of the transformer and whether it is a candidate for removal.