What's the difference between selectivity and filiation?
Hint: it's about automatic fuses.

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).]

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


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

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).]

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...)

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?

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!

Well, I must say:
I underestimated you!
I know that it's not a belgian term, because the Belgians only copy the French.