Article 4.7.2P : Principle of operation of CBCT in iELR.
Principle of Operation
CBCTs work on Kirchoff's principle that the sum of currents at any point in a circuit is zero. Hence in
case a leakage current exists in a circuit, it causes the sum of currents upstream of the leakage point to be
non-zero. This current is reflected in the secondary output of the CBCT and in case this current crosses
the threshold current (i.e. the set value on the relay), the earth leakage relay trips.