Core Balanced Current Transformer (CBCT)

In CBCT three phase cables passes through it. In a balanced 3-phase system the summation of three ph current is zero, hence the output will be zero. But in case of any unbalance, there will be some output. According to the pre-set value output current(indicates the fault) the protection scheme will operate.

How it balance the Three cores load at a time.

A 3 phase CBCT, as used in earth leakage protection, compares the VECTOR sum of the 3 currents to the neutral current.