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# Protection Riddle No.86 – 4-pole ELCB Operation

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• #846
asad

Dear i just remove N wire from 4 pole Elcb but still no triping, and as we know our system is never balanced so ir,iy,ib never equal to each other and never in=0 so at which condition 4pole Elcb trip???
Dear i just remove N wire from 4 pole Elcb but still no triping, and as we know our system is never balanced so ir,iy,ib never equal to each other and never in=0 so at which condition 4pole Elcb trip???
give me a solid reason.

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• #2768
Hamid

Generally for healthy and earth faulted conditions in 4 wire system, we can write: a- Healthy condition : ir+is+it+in=0 b- Earth faulted condition: ir+is+it+in=ie (earth fault current which cause ELCB tripping) In health condition, when you remove neutral current, you force the neutral current to zero amount and ir,is,ir changing, but you have already : Ir+is+it=0 and in=0 and consequently ie=0 (ELCB no tripping) In fact in all earth faulted conditions we face to unbalance current systems but its vice versa is not correct.

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