一起220 kV断路器本体非全相保护误动故障分析

Fault Analysis of the Open-phase Maloperation for a 220 kV Breaker

220 kV断路器本体非全相保护是保障断路器安全稳定运行的重要后备保护。针对一起220 kV断路器本体非全相保护误动的故障,对该类断路器本体非全相保护回路进行深入分析,发现保护回路设计可靠性差,保护的跳闸出口只由时间继电器的动作决定。为此,通过完善保护的跳闸出口回路并增加继电器自保持回路,使断路器本体非全相保护的跳闸出口由继电器和断路器辅助触点共同决定,并有效避免继电器触点的断弧。该回路的改进消除了继电器误动的隐患,提高了断路器本体非全相保护回路的可靠性,保证了电网的安全稳定运行。

The open-phase protection for a 220 kV breaker is an important back-up measure for safety and stable operation.A detailed analysis is made on the secondary circuit for the open-phase protection and an accident associated with this type of protection for 220 kV system,triggered by the open-phase maloperation.By the fault analysis,we find that the reliability of the protection circuit is not satisfactory and the tripping output circuit is only decided by the action of the time relay.Wherefore, through the improvement of the tripping output circuit and the addition of the relay self-holding circuit, the tripping output circuit of the open-phase protection for breaker is decided by the relay and the auxiliary contacts of the breaker.At the same time, the broken arc of the relay contacts is effectively avoided.By the improvement of the open-phase protection circuit, the hidden trouble of the relay maloperation is eliminated, and the reliability of the open-phase protection circuit is improved, and the safe and stable operation of the power grid is ensured.