1. Instant follow-up
The user decides whether to invest in this loop. Instantaneous tripping is divided into: single-phase tripping, two-phase tripping, three-phase tripping and three-phase tripping. After the three circuits exit, the circuit breaker will be tripped again. The above three circuits can only issue tripping commands when the starting component is activated.
· Single-phase follow-up trip: When the single-phase trip signals of Ta, Tb, and Tc are received from the line protection, and the high-set current components of the corresponding phases act, instantaneous phase-division tripping occurs.
· Two-phase tripping and three-phase joint tripping: After receiving and only receiving the two-phase tripping signal from the line protection, and the high-set current component of any phase acts, the three phases will be jointly tripped after 15ms delay.
·Three-phase follow-up trip: When a three-phase trip signal is received and the high-set current element of any phase acts, the three-phase trip outlet will be instantaneous.

2. Judgment of AC voltage disconnection
The criteria for judging AC voltage disconnection are: the protection does not start, and the three-phase voltage vector sum is greater than 12V, and a TV short-line abnormal signal is sent after a delay of 1.25s. When the TV is disconnected, the low power factor components are disengaged, the synchronization detection and voltage-free coincidence detection functions are disengaged, and other functions are normal. When the three-phase line voltage returns to normal, it will automatically resume normal operation after 10 seconds.

3. Abnormal alarm at tripping position
When the TWJ operates and there is current in the phase line, or the TWJ positions of the three phases are inconsistent, a TWJ abnormality will be reported after a 10S delay.
Circuit breaker protection mainly includes: circuit breaker failure protection, automatic reclosing, charging protection, dead zone protection, three-phase inconsistency protection and instantaneous tripping. This article mainly discusses circuit breaker protection in 3/2 wiring mode.