Short Circuits in Encapsulated Transformers

I would apply sufficient current to the transformer so that the short circuit heats up and breaks. Then, by xray, you should be able to find the short by looking at the resin to find the burnt spot.

Dear Sir, In potential TRX the cause for S/C may be due to poor quality of winding wire and insulation seperators and loose core which develops additional heat in EI core. POOR FERRITE QUALITY in case of Ferrite cored trx. The same can be attributed for current trx. also. X rays will not reveal any insulation failures.Only breakge of wires can be seen. All focusing on one and only one point That is QUALITY of wires and Insulations. If U comprmise Quality of U'r product against price U have to take up these sort of results which will give a bad brand name. We in INDIA tend to do this to cut down mfg. cost by compramising on quality. Use Good QUALITY materials and earn Good Brand Name. P.S.Nagesh Vibgyor Energy Solutions Chennai - India

1 If you have a wound coil that is potted, to cause a turn to turn failure you need an extreme transient so that the potential can jump turns and burn/fuse the wire.

Is there any chance of extreme transients, lightning, heavy contactor loads being dropped etc?

2 There is a chance that the potting compound is actually causing the enamel to fail due to the ability of one of the potting components being a strong enough solvent to penetrate and swell the enamel. Then the heat of curing the potting compound can break the wire by stress, and the wire with degraded/swelled enamel can touch = shorted turn