Gas Insulated Switchgear

[jflan13]

Over the past two years I have been doing commissioning work with Siemens and ABB. Typically they hire my company to do the apparatus testing for the GIS, voltages 69KV - 500KV. Does anyone have expierence with Power Factor testing this equipment, or is this unique to the utility having these installed?

[SecondGen]

Over the past two years I have been doing commissioning work with Siemens and ABB. Typically they hire my company to do the apparatus testing for the GIS, voltages 69KV - 500KV. Does anyone have expierence with Power Factor testing this equipment, or is this unique to the utility having these installed?

We do power factor testing all the time at my shop. Mostly medium-voltage transformers and gas insulated switches, not much switchgear. Biggest I've done was a 230kV Sf6 circuit switcher & transformer lineup, other than that its usually 69kV and lower.

[Ore905]

Over the past two years I have been doing commissioning work with Siemens and ABB. Typically they hire my company to do the apparatus testing for the GIS, voltages 69KV - 500KV. Does anyone have expierence with Power Factor testing this equipment, or is this unique to the utility having these installed?

It is not unique to the utility. What value do you expect to gain from power factor testing evaluation of the insulation in watts? Evaluation of the entrance bushing you are testing?

In my experience with gas equipment gas sampling of dew point and contamination is most valuable just as oil samples are with transformers.

Does anyone here have information on power factor testing the gas medium specifically.

[Ore905]

We do power factor testing all the time at my shop. Mostly medium-voltage transformers and gas insulated switches, not much switchgear. Biggest I've done was a 230kV Sf6 circuit switcher & transformer lineup, other than that its usually 69kV and lower.

You are talking about an outdoor circuit switcher with an insulator to evaluate. He's asking about transmission level GIS it looks like giant water pipes.

[jflan13]

It is not unique to the utility. What value do you expect to gain from power factor testing evaluation of the insulation in watts? Evaluation of the entrance bushing you are testing?

In my experience with gas equipment gas sampling of dew point and contamination is most valuable just as oil samples are with transformers.

Does anyone here have information on power factor testing the gas medium specifically.

How it was explained to me that in the event of a trip out, purity and contaminants along with power factor testing can show if there was a event inside the GIS. When Siemens commissions it they finish with a HIPOT test, that is their requirement for testing. Getting the HIPOT there for a trip out isnt really feasible, two tractor trailers to bring in the big one and a couple of days to setup. I agree with you that gas testing is the most valuable.

As for the power factor testing, Doble doesn't have anything built up database wise yet. When performing the tests we look for comparisons to the other phases. each set up is unique between number of internal insulators, PT's attached, length of the gear, and the injection points.

[Ore905]

How it was explained to me that in the event of a trip out, purity and contaminants along with power factor testing can show if there was a event inside the GIS. When Siemens commissions it they finish with a HIPOT test, that is their requirement for testing. Getting the HIPOT there for a trip out isnt really feasible, two tractor trailers to bring in the big one and a couple of days to setup. I agree with you that gas testing is the most valuable.

As for the power factor testing, Doble doesn't have anything built up database wise yet. When performing the tests we look for comparisons to the other phases. each set up is unique between number of internal insulators, PT's attached, length of the gear, and the injection points.

I guess power factor gives you some idea I was always taught that power factor was designed for oil filled equipment. It would be interesting for doble or omicron to come up with something definitive for evaluating gas filled equipment similarly. As with any insulation testing previous values are of course the key.

I know the hi-pot isn't feasible as I have seen it done as well.

[jflan13]

I guess power factor gives you some idea I was always taught that power factor was designed for oil filled equipment. It would be interesting for doble or omicron to come up with something definitive for evaluating gas filled equipment similarly. As with any insulation testing previous values are of course the key.

I know the hi-pot isn't feasible as I have seen it done as well.

We have used it to prove a couple minor issues, but any of a multitude of other tests provided the same knowledge. I had a three phase 345KV breaker fail on one phase. A cotter pin fell out and prevented one pole from closing. You could see a major change in the power factor readings from the previous tests. But you could use contact resistance to see it, or just a simple continuity test. Since this was the first time myself, the company reps, and the utility saw an issue like this we got the chance to run a couple of different test to confirm what we thought was occurring. the most definitive test on the breaker was the closed gap test. It gave the same result as the individual breaker test and a very similar result on the open gap test when attached to the half of the breaker that didn't operate.

Beyond something like that, I haven't seen post fault results or a failure of a GIS, I would like to see if it actually shows a significant change or if it doesn't matter.