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GSU 200 MVA is leaking oil from the HV CT Terminal Cover-Area

GSU 200 MVA is leaking oil from the HV CT Terminal Cover-Area

GSU 200 MVA is leaking oil from the HV CT Terminal Cover-Area

I have a 1994 Cooper oil filled Conservator type transformer that is leaking oil from the HV CT cover area. It's been re-torqued and it still leaks. I'm trying to find a new terminal board or container and I've had no response so far. I've received the following response so far from Eaton:

"Back in the mid 1990’s, Cooper Power Systems sold the McGraw-Edison breaker product line, and large power transformer product line, to Pennsylvania Transformer Technology, Inc. This sale included all requests for legacy parts, drawings, service, etc.

To obtain information on these products, please contact Pennsylvania Transformer Technology at:

(724) 873-2100

No response yet to my email but it's only been a couple of days. Anyway I contacted a fellow retired utility engineer and he said a new terminal interface is ideal. He said he has poured epoxy in the terminal compartment in the past.

Has anyone had this problem and how did they fix it?

Sparkdog 2023

RE: GSU 200 MVA is leaking oil from the HV CT Terminal Cover-Area

To stop the leak - first study from where it is coming- failure of the gasket at fixing joint to tank, breakage of the terminal board, etc, etc.
When you use epoxy oil sealants to stop leaks, oil should not ooze out to pollute the epoxy. You drain a few liters of oil after closing the valve between the tank and the conservator. The vacuum developed will stop the leak. Clean thoroughly the area of oil. Apply sealant. Keep the vacuum for the resin curing time. Open the valve to flow oil from the conservator to the tank. BUT NEVER charge the transformer immediately. Under vacuum, all air dissolved in oil would have come out from oil as fine bubbles and sticking to winding parts. Keep several days for the air to dissolve back into oil. Better conduct a hot oil circulation to remove all air bubbles from inside the transformer before re-energization.

RE: GSU 200 MVA is leaking oil from the HV CT Terminal Cover-Area

Agree with Ramachandran Sir! This is certainly doable by the maintenance staff at site as an immediate measure.
Also keep in mind:
If the CTs and CT secondary terminal blocks are part of the bushing turret (that is typically above the tank top cover), do ensure venting is done properly on turret top as well as on bushing top before returning the transformer to service.
This applies to other bushings as well where there may not be a problem now.

RE: GSU 200 MVA is leaking oil from the HV CT Terminal Cover-Area

Thank you guys for your input. Before 2018 I would have called Pennsylvania Transformer, but I've lost use of my voice since then. The epoxy solution seems viable and the negative pressure aspect of sucking in the epoxy is one I hadn't thought of, but it makes sense. Good stuff!!


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