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Protection Riddle No.86 - 4-pole ELCB Operation
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.
Author : asad - From: pakistan
Mon, November 14th, 2011 - 10:00
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. 
Author : Hamid - From: Iran- Firoozabad fars
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