Adjustable breakers

[brizospark]

In the case of adjustable breakers which value goes in the column for protective device

i.e. if it a a 200a breaker and it has been tuned down to 180a?

 

[DurhamSparky]

i would put 180A but make a note that the unit is adjustable to 200A

 

[Guest 004]

You will then have to look at the graph of that type of breaker in BS7671, to get Zs values

 

[Engineer54]

As the 200A MCCB has been adjusted down to 180A that is the value to be taken. Are there any other adjustable parameters on this MCCB?? Always remember that adjustable MCCBs do not have a common trip value like MCB types. (B,C,D,) They are can be considered as ''one offs'' as there protection levels will vary according to the adjustment values being set on such breakers....

 

[Guest123]

You will then have to look at the graph of that type of breaker in BS7671, to get Zs values

If it is an MCCB to BS 60947-2, there are no max Zs values in BS 7671 for them. They can either be calculated or obtained from the manufacturer.

 

[Guest 004]

or you can use Amtech

 

[Guest 004]

If it is an MCCB to BS 60947-2, there are no max Zs values in BS 7671 for them. They can either be calculated or obtained from the manufacturer.

yep stand corrected, you can get the graphs from the manufacturers

 

[Guest123]

Bit of guff here for you......

 

[Guest 004]

^ good reading, and thanks