Green Liquid Leaked from CT Secondary Terminal Board of 132 kV GIS

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Discussion Overview

The discussion revolves around the discovery of a thick, sticky green liquid leaking from the secondary terminal board of a 132 kV GIS Current Transformer. Participants explore potential causes for the leak, including the nature of the liquid and its implications for equipment safety and integrity.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant reports a leak from two feeders and mentions previous issues with cracks in the CT secondary terminal board, raising the possibility of similar damage.
  • Another suggests that the liquid is likely insulating oil mixed with a preservative.
  • Some participants share experiences where vinyl or plasticizers reacted with copper, resulting in a dark green sticky substance, indicating a potential chemical reaction.
  • A warning is issued regarding the potential presence of polychlorinated biphenyls (PCBs) in the liquid, highlighting their toxic nature and recommending testing before contact.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the green liquid, with some proposing it as insulating oil while others suggest it may be a reaction product from materials used in the cables. There is no consensus on the exact cause or implications of the leak.

Contextual Notes

Participants note the historical context of previous issues with the CT secondary terminal board, but the current situation remains unresolved regarding the source and safety of the liquid.

Who May Find This Useful

Electrical engineers, maintenance personnel, and safety professionals involved in high-voltage equipment management may find this discussion relevant.

Suri
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Hye everyone!

An unknown thick-and-sticky green liquid was found leaked from 2 out of 9 feeders, of our 132 kV Switchgear. The liquid was leaked through the cable gland that connected to the Secondary Terminal Board insulating cap of the Current Transformer, at the GIS.

I had done:
1) gas leak test - no gas leakage detected
2) hotspot test using thermography camera - no hotspot.

According to our chargeman, around 6-7 years ago, there is a case when they found out that inside the CT secondary terminal board, there was cracks. And all CT secondary board for all feeders was then replaced.

I just wondered if the same thing happened. Or the green liquid was just a kind of grease or softener for the cable.

Hopefully someone can help me. Thank you!
 
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It is probably insulating oil with some kind of preservative.
 
I have had cases where the vinyl or plasticizers reacted with the copper and created a dark green sticky substance. In one case it was clear insulation and I could see the fouling all along the cable.

BoB
 
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rbelli1 said:
I have had cases where the vinyl or plasticizers reacted with the copper and created a dark green sticky substance. In one case it was clear insulation and I could see the fouling all along the cable.
I have also experienced that corrosion in ordinary lamp cord with clear vinyl insulation. Annoying!
 
I would be careful. Polychlorinated biphenyls (PCBs) were widely used as insulating fluids in electrical equipment for many years. Wikipedia says, "One estimate (2006) suggested that 1 million tonnes of PCBs had been produced. 40% of this material was thought to remain in use. Another estimate put the total global production of PCBs on the order of 1.5 million tonnes. The United States was the single largest producer with over 600,000 tonnes produced between 1930 and 1977. The European region follows with nearly 450,000 tonnes through 1984."

These things are toxic. I would get it tested before you come in contact with it, if it's not too late.