Coordinating wiring between leakage protector and fuse, isolating switch and circuit breaker c

The wiring of leakage protectors and fuses, isolating switches and circuit breakers. The wiring of leakage protectors
    with different action modes is as shown in the figure. In the figure, QF is the circuit breaker and QS is the isolating switch or knife switch. In the picture (a), the fuse FU can be used; in the picture (c), the circuit breaker can be used.