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Engineering Fields - Power Engineering - New Member

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VFTOs and Trapped Charge with Circuit Breaker Switching

08/10/2017 11:20 AM

Dear Sirs or Madams: We all know the switchings of disconnector in GIS can lead to VFTOs, especially with the trapped charge -1pu in the short busduct, how about the switching of circuit breaker in GIS? -1pu trapped charge is possible or impossible ? also can leads VFTO or not? The trapped charge can exceeds 1pu or not? I am eagerly want to know! Thanks a lot Weijunmei in Shenyang

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#1

Re: VFTOs and trapped charge with circuit breaker swithing

08/10/2017 1:27 PM

Modeling Of Gis for Measurement of VFTOS

http://www.ijeit.com/vol%202/Issue%204/IJEIT1412201210_06.pdf

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#2

Re: VFTOs and Trapped Charge with Circuit Breaker Swithing

08/10/2017 8:46 PM

It seems to be an odd question? only one reply, i

hope i can get a lot of replies!

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Guru

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#3
In reply to #2

Re: VFTOs and Trapped Charge with Circuit Breaker Swithing

08/10/2017 8:58 PM

If you use names instead of initials you might do better.... Gas-insulated high-voltage switchgear (GIS) ....although the meaning is apparent in the field, we cover all fields and all the acronyms seem to get confusing, (you'd be surprised how many similar acronyms are used). so we prefer that the poster include the long version to avoid confusion...

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#4
In reply to #3

Re: VFTOs and Trapped Charge with Circuit Breaker Swithing

08/10/2017 9:27 PM

Thanks a lot,it is true, i will remember this tip!

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Power-User

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#7
In reply to #2

Re: VFTOs and Trapped Charge with Circuit Breaker Swithing

08/11/2017 9:01 AM

The circuit breaker opens very quickly in a designed time to reduce the number of restrikes, usually in milliseconds for arc extinction. That operation, being more controlled, can be measured and observed more consistently, and the components are designed to minimize restrikes.

A link is designed to create a temporary safe isolation in the circuit, at a lower cost, concentrating on good circuit continuity when in service. Think of open air disconnect switches designed to interrupt only transformer magnetizing current, with arc horns (stiff wires) that draw out the arc until it is too cool to survive. That equipment was designed before anyone had the equipment to fully analyze the spectrum of the interruption event.

Very good paper found by Mr. Eagle, though haven't puzzled this phrase out...

(Transients due to trade, such as "3½ in disk drive." )

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#9
In reply to #7

Re: VFTOs and Trapped Charge with Circuit Breaker Swithing

08/11/2017 10:35 AM

dear sir:

Reduce the number of restrike,it is right! but if there is only two times restrike during cb switching, the vfto exists! here,i want to know the real fact, the concept! do you agree with me?

best regards!

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#6

Re: VFTOs and Trapped Charge with Circuit Breaker Swithing

08/11/2017 6:46 AM

<...We all know...> Absolute nonsense.

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#10
In reply to #6

Re: VFTOs and Trapped Charge with Circuit Breaker Swithing

08/11/2017 10:39 AM

you are right!

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#8

Re: VFTOs and Trapped Charge with Circuit Breaker Swithing

08/11/2017 10:34 AM

What is VFTO?

What unit of measurement is a pu?

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#11
In reply to #8

Re: VFTOs and Trapped Charge with Circuit Breaker Swithing

08/11/2017 1:26 PM

Per Unit = pu

https://en.wikipedia.org/wiki/Per-unit_system

Very Fast Transient Overvoltage = VFTO

https://www.researchgate.net/file.PostFileLoader.html?id=56e262ca5b49526b023d80a0&assetKey=AS%3A338336024678400%401457677002146

Basic insulation level (BIL), Gas insulated substation (GIS), Air insulated substations (AIS)...

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#12

Re: VFTOs and Trapped Charge with Circuit Breaker Swithing

08/11/2017 1:30 PM

VFTO in this context usually means Variable Frequency Transient Oscillations which are a result of high speed, high current, high voltage switching operations.

There are plenty of scholarly articles available from IEEE, CIGRE, IEC, and others.

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Anonymous Poster (1); Mikerho (1); PWSlack (1); RAMConsult (1); rwilliams (1); SolarEagle (3); weijunmei (4)

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