500kV GIS breaker Open/close Time Testing 1

[alikhan007]

Guys, need help regarding open close time testing of 500kv GIS breaker. The close time of all three phases were about 66.7,67.2,67.3ms. But as per vendor specifications. The value of closing time should be around 48~60ms.
I have contacted vendor in this regard but now he is telling that value under 100ms is acceptable untill and unless all three phases are synchronously closed.
Does this 100ms value comply. Any reference of IEC standard can I use in this regard?

 

[crshears]

I don't know about that, but your Authority Having Jurisdiction [ AHJ ] might have something to say about that; very often if not most of the time it is the AHJ that calls the shots when it comes to fault clearing time.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[davidbeach]

Close vs open. At 500kV I’d expect trip times of less than 35ms but the close times will be longer. The exact close time becomes important if you’re doing point on wave closing.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[alikhan007]

Yes, the open (trip) time is less than 20ms. Thats qualified as per our acceptance criteria. But The close time is a bit higher than the range. Any IEC standard mentioning GIS breakers time testing range?

 

[crshears]

Davidbeach wrote:

The exact close time becomes important if you’re doing point on wave closing.

Indeed it does! Independent pole operation, specifically independent pole closing, is a cat of a different stripe; my apologies for gapping on that the first time around.

My [present] utility uses IPO breakers for placing our highest-MX-rated 230 kV capacitors in service, and the IPO breaker control schemes employ a learn-as-you-go synchronous control unit to iteratively adjust, tweak, and time the pole closiing this time around based on "memory" of the length of time it took each pole to operate, the exact contact closing time using CTs, et cetera and so forth, of the previous so many operations.

Given that, and based on what I've encountered, the longer contact closing time shouldn't become an issue unless the closing time becomes so unacceptably long that the possibility of pre-strike/re-extinguishment with its production of very unpleasant waveforms starts to enter the picture.

Hope this helps.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[alikhan007]

crshears

So what should be the acceptable limit of closing time?

 

[thermionic1]

Our MEPPI breakers have an * in the close time specs. The fine print shows that the published time does not include the 52x relay time.
We sense the start time from a spare set of contacts of the 52x and program the test set to call that the start time. In the end we have the total time and the time from 52X picking up, which matches the published specs. The total time minus the 52x time is also calculated. I asked MEPPI why they do things this way and they stated that different customers have different specs (or vendors / models) for the 52X, therefore they only publish a single time.

I've heard horror stories of people bypassing the 52X altogether and then continuing on to complex tests like reclosing and trip free. They story I heard is that the poor guy who did this destroyed the mechanism.