RCCB/MCCB/MCB related question
RCCB/MCCB/MCB related question
(OP)
hi all,
i'm quite new to electrical engineering field...particularly related to building wiring, switchgear, switchboard, circuit breakers, etc
not sure how to ask this question but here goes...
i've been looking at some electrical drawing of Main Switch Board and i notice there MCCB and RCCB (residual current circuit breaker) with various ratings 63A, 40A, etc
i understand that this values govern the amout of current that is allowed into the MSB. However, i also notice that there a smaller value of current which is related to them. This values is in milli Amps (e.g. 30mA, 100mA)
i was told that this is the trip current (the amout of current that would trip the circuit) so my question is as follows
1. how does this trip current come about?
2. when we see a RCCB with say 63A rating with 100mA trip current, is this 100mA the amout of current that that exceeds the 63A rating (intake) or is it the current that is present in the neutral line when a short occurs?
3. i also heard that there is such a thing as earth leakage current, is this the current that leaks through the earth line from the system?
as you can see i'm quite at a loss here...
sorry if my question seems to novice but i would really hope that someone could clerify it for me.
thanks in advance for you help
Regards,
Cromr
i'm quite new to electrical engineering field...particularly related to building wiring, switchgear, switchboard, circuit breakers, etc
not sure how to ask this question but here goes...
i've been looking at some electrical drawing of Main Switch Board and i notice there MCCB and RCCB (residual current circuit breaker) with various ratings 63A, 40A, etc
i understand that this values govern the amout of current that is allowed into the MSB. However, i also notice that there a smaller value of current which is related to them. This values is in milli Amps (e.g. 30mA, 100mA)
i was told that this is the trip current (the amout of current that would trip the circuit) so my question is as follows
1. how does this trip current come about?
2. when we see a RCCB with say 63A rating with 100mA trip current, is this 100mA the amout of current that that exceeds the 63A rating (intake) or is it the current that is present in the neutral line when a short occurs?
3. i also heard that there is such a thing as earth leakage current, is this the current that leaks through the earth line from the system?
as you can see i'm quite at a loss here...
sorry if my question seems to novice but i would really hope that someone could clerify it for me.
thanks in advance for you help
Regards,
Cromr






RE: RCCB/MCCB/MCB related question
The current 'going out' to the load on the phase conductor is compared with the current 'coming back' on the neutral conductor.
In a healthy circuit these currents are equal. However if the circuit has an earth fault there will be a differnce in these values. If the difference is greater than the trip rating (100mA in your case) then it will trip.
The 63A rating is the continuous maximum load it can carry.
You can get a device which is a combined MCCB/RCCB which will protect against short circuits, overloads and earth leakage.
This is basic but hope it sets you off in the right direction.
RE: RCCB/MCCB/MCB related question