Transformer
Transformer
(OP)
Hi,
We had a breakdown of a cast resin tranformer, rated @ 3500 k VA 11 k V/ 415 V. The breakdown occured on one phase and the LV winding was shorted to ground. This transformer was working at a very high temperature, as do use to operate cast resin types,<= 115 deg C. I am having an argument with my insurance company because they are willing to pay for the repair/replacement of the the damaged coil only. I have advised for a replacement because I am of opinion that the other two coils will sooner or later break down. A simple megger test, HV and LV, on the two remaining coils did not show anything wrong. I don't want to effect any destructive testing on the two remaining coils. Any advice? I have attached a picture of the damaged winding.
The transformer is a Schneider one.
Regards.
Guardiano
We had a breakdown of a cast resin tranformer, rated @ 3500 k VA 11 k V/ 415 V. The breakdown occured on one phase and the LV winding was shorted to ground. This transformer was working at a very high temperature, as do use to operate cast resin types,<= 115 deg C. I am having an argument with my insurance company because they are willing to pay for the repair/replacement of the the damaged coil only. I have advised for a replacement because I am of opinion that the other two coils will sooner or later break down. A simple megger test, HV and LV, on the two remaining coils did not show anything wrong. I don't want to effect any destructive testing on the two remaining coils. Any advice? I have attached a picture of the damaged winding.
The transformer is a Schneider one.
Regards.
Guardiano






RE: Transformer
RE: Transformer
The much smaller sizes of cast resin transformers that I am familiar with are cast en-block. The windings are not visible.
Link
This thread may be informative:
Cast resin transformers
thread248-402679: Cast resin transformers
And lastly, is there any core damage?
Bill
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"Why not the best?"
Jimmy Carter
RE: Transformer
RE: Transformer
Waross, thanks for the post. I refer to this quote from ScottyUK, "Schneider seem to have missed partial discharge as a problem, or at least seem to think their transformers don't experience it. I agree with Gunnar that the 'Geafol' type are among the best of the breed. I'm not convinced that Schneider have PD completely fixed. Equally I'm not sure how many users actually look for PD to know that they have it. Being PD-free on commissioning day doesn't always equate to being PD-free after years of service, especially with organic insulation materials. "
Guardiano
RE: Transformer