What Is The Three-phase Inconsistent Protection Function And Application Of Circuit Breaker?

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Find out what the three-phase inconsistency protection of a circuit breaker is through the following conditions:

1,The origin of three-phase inconsistency: due to the quality and operation of the equipment and other reasons, the three-phase circuit breaker may be inconsistent in operation, and eventually only one or two phases jump away, and be in a non-full phase abnormal state.

2,The hazard of three-phase inconsistency: when the system is in a non-full-phase operation state, the negative sequence, zero sequence and other components in the system will cause certain harm to the electrical equipment, and also affect the correct action of the system protection device, so the power system is not allowed to run non-full-phase for a long time.

    If the line coincidence is unsuccessful, there will be no other protection to eliminate this fault when the system enters non-full phase operation, so the circuit breaker of the split-phase operation is installed with non-full phase protection (three-phase inconsistent protection), and when the system is non-full phase for a certain period of time, it will jump away from other phases.

3,Three-phase inconsistency implementation: The protection function to eliminate the abnormal state of three-phase inconsistency is generally implemented in the circuit breaker body in the high-voltage or ultra-high-voltage level system, but it is also implemented in the circuit breaker protection (or line protection).

    Inconsistent protection In the circuit breaker body, the State Grid has 18 countermeasures requirements: circuit breakers with voltage levels of 220kV and above should be equipped with three-phase inconsistent protection of the circuit breaker body.

    After the circuit breaker jumps open in the single phase, if the reclosing action is in place, the circuit breaker does not reclose successfully due to pressure, machinery, secondary circuit, etc., and the three-phase must be jumped out within 2-2.5s, and it will no longer coincide to ensure the safety of the system.

    When there is no three-phase inconsistency protection in the circuit breaker, a separate three-phase inconsistency protection device can be installed. In addition to using the auxiliary contact or position contact of the circuit breaker to form a starting circuit to judge the three-phase inconsistency, the independent three-phase inconsistency protection can also use the zero sequence current and the negative sequence current to block the circuit to improve the reliability of the circuit.

1,The input of three-phase inconsistent protection: when the three-phase inconsistent protection soft pressure plate and hard pressure plate are put into operation (control word), the three-phase inconsistent protection function will work.

2,The action of three-phase inconsistent protection: the inconsistent zero-sequence open control word is put in, the inconsistent start is operated by the inconsistent zero-sequence current criterion, and then the three-phase circuit breaker is jumped through the inconsistent delay exit. The inconsistent is put into the negative sequence open control word, the inconsistent start is operated by the inconsistent negative sequence current criterion, and then the three-phase circuit breaker is jumped through the inconsistent delay exit. When the above two control words are exited, the three-phase circuit breaker is not started after the inconsistent delay exits the three-phase circuit breaker.

   The three-phase inconsistent protection action does not stop and fails, and the locking and reclosing are at the same time.

3,Locking of three-phase inconsistent protection: The circuit breaker is in the three-phase inconsistent state for 12 seconds, and the position is inconsistent alarm, and the three-phase inconsistent protection is locked.

4,The setting principle of the time relay of three-phase inconsistent protection: the delay setting value of the three-phase inconsistent protection of the relay protection device should be able to avoid the action time of the recloser. The circuit is used by the user to decide whether to invest or not.