Multi-pole leakage protector circuit a

Multi-pole leakage protectors, such as three-pole three-wire, four-pole three-wire, etc. Their working principles are similar to those of single-phase current leakage protectors
and are left to the readers to analyze by themselves. As shown in the figure, Qs is the circuit breaker and TA is the zero sequence current transformer. L is the release coil, and N is the control circuit
composed of electronic circuits .