The circuit breaker is disconnected mainly because the bow contact bar or the contact wheel is not in contact with the overhead line, or the power cable is broken and the terminal is loose, resulting in no voltage of the locomotive. At this time, the locomotive lighting is dull, the spindle handle all gears that are started cannot be transported. The open circuit of the knife automatic switch is mainly due to the burning and falling of the contact contact, the power supply wire is broken, the terminal is disconnected, and the control circuit is disconnected, so that the control circuit has no voltage. At this time, the locomotive illumination light has light, but the positions of the spindle start are Still can't walk. The partial disconnection of the controller should be turned on. It is mainly caused by the main contact or the auxiliary contact falling off, the contact failure, and the broken line. It can cause the spindle handle to start at various positions without driving or part of the starting position locomotive. The open circuit of the scooping starting resistor will cause the spindle to start at different positions without taking the car. According to the starting condition of different gear positions, the breaking of a certain starting resistor can be judged. The internal circuit of the motor is broken. Secondly, it is mainly the main magnetic pole or the commutating magnetic pole is broken, or the electric first leak is connected. The wiring is broken.