By charging motor circuit analysis, to make the energy motor must meet the following conditions, first trouble-free power supply and the power supply automatically switches the motor 8M closed, DC contactors 88M action, the contact is closed and contact a good motor Interior line short circuit fault-free. Charging motor circuit wiring complete loose bolt. In the actual work. Because the motor protection circuit is perfect, so the lower incidence of motor failure, the network and the operation of the circuit breaker, not taking into account other factors, the charging motor does not start 88M mainly due to the DC contactor contacts are not closed or early return. The reason for this may be the spring energy storage limited contact 33hb failure, limited contact 33hb after the breaker cannot be good closed contactor 88M, but this is the probability of failure is very small; in actual field work, charging motor does not start after the main reason is that the breaker, contactor 88M contacts are closed. Connect the charging motor, because electric motors driving mechanical reasons, 88M or DC contactor contact poor contact, causing the motor to not work overload. Motor thermal relays 49M action start the auxiliary relay 49M. Cut off the charging motor circuit.