Abstract：The ABB LTB245 series breaker is one of the common switching equipment in modern substation. The spring self-energy SF6 extinguishing device is adopted. The basic structure and operation principle of LTB245E1 circuit breaker are introduced. This paper analyzes a case of the failure of the switch closing due to the failure of the closed turning arm, but unsuccess after operation several times. Because of the BW wheel (energy storage limit roller) fixed plate has deviation and transformation in the energy storage process, the operation mechanism has been stored over energy. So the working condition of coil spring is affected and the Energy storage motor can not complete energy storage. The two typical cases where the breaker cannot be closed due to mechanical failure in the operating mechanism box. The analysis of the fault causes can provide reference for the transformer. At the same time for the related manufacturers design personnel equipment upgrade to provide the basis.