Abstract:With the development of social economy, the development of science and technology is also advancing by leaps and bounds. The scale of operation of GIS combined electrical appliances (including circuit breakers) is gradually increasing. It mainly has a high degree of integration, a small footprint, and daily maintenance. The advantages of less workload, GIS is difficult to overhaul, long power outage, and wide range of influence, and has been the focus of manufacturers and users. In this paper, six GIS circuit breakers of a 220kV substation in Liupanshui Power Supply Bureau are used in the pre-test process. There are concentrated defects in the parameters of the opening time. The causes of the opening of the circuit breaker are studied by analyzing the causes of the concentrated defects. Cooperate with the situation, combined with various factors that may affect the time parameters, finally through several methods of comparison, using the stroke and clearance of the adjustment coil to reduce the tripping time processing method, and analyze and summarize the causes of such defects , put forward effective preventive measures to ensure the safe and stable operation of the power grid.