An Analytical Study of a Tripping by Three-phase Inconsistent Fault in 220kV GIS Circuit Breaker

The electrical system in China, the ability to function safely and reliably of larger power grid depends on the 220kV core power network, with also more related to the normal energy supply of megacities. This paper takes an unplanned outage of 220kV line caused by a circuit breaker failure in the central business district (CBD) of Guangzhou city as an example. Starting from the cause of tripping, it conducts a comprehensive analysis from the operating conditions of the circuit breaker control circuit, tripping circuit, and protective device, as well the implementation of countermeasure requirements at the management level. To accurately find out the reason of the failure and put forward preventive and control strategies for the similar incidents. Its accuracy and practicality are demonstrated after more than a year of operation.