Cooper Single Phase Transformers

[OffTap2020]

Recently we received quite a few Cooper 997kva 7200-277 single phase transformers, for use in some of our larger customer subs. Some have been installed, and when IR scanned, they show excessive heat( 300f) right between the secondary bushings. In this exact area between the bushings, and on the opposite side between the primary bushings is a 'grounding pad" with threaded holes. The transformers are all case grounded via the grounding pad at the base of each unit.

Question, could these pads between the bushings actually be core grounding points?
Nothing like this is referenced on any leaflet for these units, and although Cooper has been contacted, I was hoping to get some opinions or guidance from you gentleman.
If I have left out any information, please let me know.
I have included an IR scan of the unit while energized.

Regards,

OT2020

 

[OffTap2020]

Here is also a picture showing these pads between the bushings.

 

[waross]

It could be eddy currents in the pad. There is a lot of magnetic induction in that area. Transformers will often have a stainless steel insert that the bushings penetrate so as to limit hysteresis heating, The pad looks as if it was added in the field. The welding doesn't look like Cooper quality.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[pwrengrds]

Have you asked Cooper? That pad doesn't look quite right. It seems to be in an odd spot for a grounding pad, between two HV bushings.

 

[OffTap2020]

Thank you Waross and Pwrengrds.

I agree that the pad are in an odd place. But they are factory installed, they came right from Cooper The portion that looks rusted is actually just the paint peeled back because of the heat.

We should hear back from Cooper tommorow morning. A contact at Waukeshaw told me that they had heard Cooper was having problems with the single phase substation style units.


OT2020