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#133968 - 10/13/02 04:43 AM Quiz
Belgian Offline
Member

Registered: 10/10/02
Posts: 177
Loc: antwerp
What's the difference between selectivity and filiation?
Hint: it's about automatic fuses.

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#133969 - 10/13/02 12:03 PM Re: Quiz
C-H Offline

Member

Registered: 09/17/02
Posts: 1508
Loc: Stockholm, Sweden
The word filiation is used only in French, I think. The difference between selectivity and coordination between breakers is that in selectivity, a short-circuit trips the nearest breaker but not the one(s) upstream of it.

It's fairly easy to achieve selectivity with fuses: Make the upstreams fuse one or two sizes larger. With breakers, you have to ensure that the electromagnetic trip range of the two breakers doesn't overlap. For example you cannot get selectivity between a 10A type C breaker and a 16A type C breaker. The 10A breaker will trip in the 50-100A range, and the 16A breaker in the 80-160A range. There is a overlap in the 80-100A range. For this reason main fuses are often used instead of main breakers.

Coordination between breakers is used when you have a supply where the prospective fault current exceeds the rated maximum fault current of the breaker. (Typically 6 or 10kA) To prevent the breaker from melting when you have a short circuit close to the breaker, the upstreams breaker must have a higher fault current rating, exceeding that of the maximum prospective fault current.

In practice, a conventional fuse will be used for this, since a fuse cannot fail to trip.

[This message has been edited by C-H (edited 10-13-2002).]

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#133970 - 10/13/02 12:53 PM Re: Quiz
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
 Quote:
The word filiation is used only in French, I think.

I've never heard of the word, so it could well be French only!

 Quote:
in selectivity, a short-circuit trips the nearest breaker but not the one(s) upstream of it.


That's what in British terminology is usually called "discrimination."

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#133971 - 10/13/02 01:18 PM Re: Quiz
Belgian Offline
Member

Registered: 10/10/02
Posts: 177
Loc: antwerp
C-H, I'm impressed! I didn't think anybody could have answered this one!

Do you know the difference between Partial and Total selectivity?

Is there a word in english for filiation? Or is it that they don't use this technology? It can save a lot of money, especially when doing industrial installations.

[This message has been edited by Belgian (edited 10-13-2002).]

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#133972 - 10/13/02 01:20 PM Re: Quiz
C-H Offline

Member

Registered: 09/17/02
Posts: 1508
Loc: Stockholm, Sweden
One never uses the right word, does one?

It seems selectivity is the right word in both French and Swedish. Thus, I didn't react when Belgian used it. (Here, discrimination is a criminal offence...)

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#133973 - 10/13/02 01:23 PM Re: Quiz
Belgian Offline
Member

Registered: 10/10/02
Posts: 177
Loc: antwerp
Before putting this word in this quiz I made a transalation on the internet and guess what I came up with?.....filiation.
That's why I used this term.
Does anybody know the term in English?

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#133974 - 10/13/02 01:37 PM Re: Quiz
C-H Offline

Member

Registered: 09/17/02
Posts: 1508
Loc: Stockholm, Sweden
Partial discrimination (selectivity) is when there is discrimination up to a certain value for the fault current. Total discrimination means that no matter how high the fault current, only the first breaker will trip.

The concepts of breaker cooperation and discrimination are universal, not limited to Belgium.

BTW: The Babelfish translator on Altavista simply simply gives you the word you typed in if it doesn't recognize it. Without warning or error message!

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#133975 - 10/13/02 01:42 PM Re: Quiz
Belgian Offline
Member

Registered: 10/10/02
Posts: 177
Loc: antwerp
Well, I must say:
I underestimated you!
I know that it's not a belgian term, because the Belgians only copy the French.

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