Oil current transformer

[tem1234]

We dismantle high voltage old oil current transformers. When we remove the oil, there is often sand or something similar in the oil. Is this really sand? To send to the decontamination, we must indicate the type of material and we are not sure.

Thanks and happy holidays

 

[tem1234]

After some research, it might be quartz sand. Do you are aware of any other kind of sand use in ct design?

 

[ScottyUK]

If it is an old CT then it could be from the cement grout used to fix the porcelain bushings into the casing. Quartz is a fair guess..

 

[scottf]

There were some old designs that were called "minimum oil designs" that used sand, or sand-like substance, to displace oil. You could be seeing that, but there would be a substantial amount of sand and not just a little in the oil.

Labeling it as quartz sand should be the most accurate.

 

[ScottyUK]

scottf,

I haven't seen that type before - was that a US or European design? Were they intended for indoor substations?

 

[prc]

It can be quartz sand to save oil and also for better mechanical withstand strength.Even now there are manufacturers who fill their CTs with quartz sand (ie sand made by powdering rock). There was an AIEE paper from GE engineers in 1940's proposing river sand in their CTs for mechanical withstand strength. Taking cue from that paper, self used to fill CTs with glass marbles during 1970's. Those days,for the same volume,glass marbles were cheaper than oil!