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Member

Join Date: Jul 2014
Posts: 9

# What Do You Mean by Filling, Signal and Blocking Pressure of SF6 Breakers?

02/03/2017 6:55 AM

Dear all,

I have 145 KV rated SF6 breakers used in our 110 KV substation. Its manufactured by ABB and has max SF6 gas pressure mentioned in the name plate as 0.9 Mpa. Also the filling, Signal and Blocking values are given as 0.7, 0.62 & 0.6 Mpa respectively. The volume per pole is 50 L.

Could you please help and elaborate on the filling, Signal and Blocking values of the SF6 gas used in this breaker.

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#1

### Re: What do you mean by Filling, Signal and blocking pressure of SF6 breakers?

02/03/2017 7:52 AM

Yes. ABB.

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Join Date: Oct 2008
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#2

### Re: What do you mean by Filling, Signal and blocking pressure of SF6 breakers?

02/03/2017 8:21 AM
8
Guru

Join Date: May 2010
Location: Liverpool, NY
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#3

### Re: What do you mean by Filling, Signal and blocking pressure of SF6 breakers?

02/03/2017 8:51 AM

"Filling" is the gas pressure of the SF6 when the breaker has been filled with the proper amount of SF6 gas for operation, at specified temperature. That is the normal operating pressure.

"Signal" is the pressure at which the low pressure switch alarm contacts will operate, to give you an indication that there has been a loss of gas and you should investigate and correct the situation. That pressure is usually chosen to be a level where there is enough SF6 pressure still in the breaker to meet its electrical interrupting specifications.

"Blocking" is the pressure value where you have lost enough SF6 gas that proper interrupting of the specified fault current level cannot be guaranteed, and the tripping (opening) operation of the breaker is blocked from occurring so that it won't go "BOOM!!!".

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Join Date: Mar 2011
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#4

### Re: What do you mean by Filling, Signal and blocking pressure of SF6 breakers?

02/03/2017 1:39 PM

Excellent!

It is refreshing when someone who knows their stuff, just lays out the correct answer with no mystery, and no extra cheese.

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