Answer / abdulsubur

Total load =187kw

p=root3*vicosphi
i=p/root3v*cosphi
we get aprorximately 400

Answer / abdulsubur

we get appoximately


cb= 400A

Answer / ramaraj.g

Selecting main CB rating first.
187KW / votages LL
187000/400
467.5 amps this type current rating is not in market
so we will go to next rating 600 Amps

Answer / abdulsubur

P= Root3*vicosphi

calculate i from this equation apploximately
we can use 400A ircuit Breaker

Answer / rajendran

Apart from the nominal operating current we have to
consider the following factors also

1) Capacity of the source
2) Fault lvel of the system
3) Breaaking capacity of the breakeer required based on the
fault level obtained..
4) Space avilable
5) cost requirements
6) Method of controls in the breaker
7) Protection facilties avilable....

Answer / bala

Selecting main cb rating depends on the type of load if it
is combination of small loads (upto 10kw) 400amps mccb is
enough.
1. if it is one motor load. first we have consider what
type of starter we are going to use. in case of star delta
starter select 600amps mccb. in case of VFD and softstarter
400amps mccb is enough.

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