In a Circuit how the MCB and Fuse ratings are calculated. And shall the fuse f

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In a Circuit how the MCB and Fuse ratings are calculated.
And shall the fuse follws the MCB or it is otherwise?

Question Posted / g.venkatesh

16 Answers
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In a Circuit how the MCB and Fuse ratings are calculated. And shall the fuse follws the MCB or it ..

Answer / sanjay kumar

FUSE RATING CAN BE CALCULATED AS FOLLOWS:
SAY A MOTOR FULL LOAD CURRENT RATING IS 30A,TAKE FUSE OF
RATING 2.5TIMES OF FLC. SO FUSE RATING WILL BE 80A.IF IN
CASE THIS RATING FUSE IS NOT AVAILABLE, WE CAN GO FOR NEXT
HIGHER LEVEL. BUT IF NEXT HIGHER LEVEL FUSE IS SO HIGH THAT
IT CANT BE TAKE THEN GO FOR SOMEWHAT LOWER LEVEL. THIS IS
BASED ON MY EXPERIENCE IN THE INDUSTRY.

SECOND PAART IS FOR MCB:

MCB SELECTION SHOULD BE SOMEWHAT HIGHER THAN FUSE RATING.

Is This Answer Correct ?

5 Yes

4 No

In a Circuit how the MCB and Fuse ratings are calculated. And shall the fuse follws the MCB or it ..

Answer / amaravathi

fuse rating will be calculated by following formula.
125% of rated current.but we can use nearest value of fuse rating value.

Is This Answer Correct ?

1 Yes

0 No

In a Circuit how the MCB and Fuse ratings are calculated. And shall the fuse follws the MCB or it ..

Answer / devamanohar

The MCB rating shall be more than the fuse rating if it is
used for the service to switch off & on while the circuit
is in service.The fuse rating shall be 200% of the rated
curent normally as it is used for short circuit
protection.If the MCB is stay put type(No operation while
in service) it can be selected for rated current or 1.2
times of rated current value.

Is This Answer Correct ?

2 Yes

2 No

In a Circuit how the MCB and Fuse ratings are calculated. And shall the fuse follws the MCB or it ..

Answer / shaik

depending on the full load capacity ratings is calculated.
It is not necessary to connect MCB and fuse both,one is
enough.if u want to connect both then first fuse the MCB

Is This Answer Correct ?

11 Yes

15 No

In a Circuit how the MCB and Fuse ratings are calculated. And shall the fuse follws the MCB or it ..

Answer / mahesh s.chorghe

MCB RATING SHOULD BE 2.5 TIMES OF LOAD CURRENT AND FUSE
RATING GRETER THAN (1.5 TIMES)MCB

Is This Answer Correct ?

14 Yes

29 No

In a Circuit how the MCB and Fuse ratings are calculated. And shall the fuse follws the MCB or it ..

Answer / moideen.t.y

Fuse size can be calculated by this formula, 225% of full
load current.
locked rotor amps is the 500% of full load current.

Is This Answer Correct ?

4 Yes

19 No

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