Answer Posted / majid amoudi

direct technical answer:-
suppose if d interviewver asks u
"for 11kva transformer what size of d ckt breaker shud b used"
answer-
11kva= 11,000va

11,000 divided by 220v(depending on various countries voltage rating)=50A
50A is d current passing thru d ckt...according to NEC(national electrical code) current shud be 125%...
so, 50* 1.25=62.5A
d breaker will trip if d current passes more dan 62.5A & d ckt breaker size shud be selected 4 times d nominal ckt breaker current i.e 62.5*4=250A.
so..a MCCB(moulded case circuit breaker) of 250A shud be used for 11kva T/F.

hi can any body send me syllabus of rrb electrical section engg... and past pepar also of any board...

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