Method, device and system for judging short-circuit fault of charging loop of rail transit electric vehicle

The invention discloses a method, a device and a system for judging a short-circuit fault of a charging loop of a rail transit electric vehicle, and the method comprises the following steps when in a constant-current charging stage: judging whether a vehicle exists in a parking space, and if yes, judging whether the total charging time exceeds a set time T0; if yes, fault judgment is carried out according to the change parameters of the voltage along with time, and when it is judged that the state is abnormal, a charging stopping instruction is sent out; if not, fault judgment is carried out according to the voltage change parameter along with time, if it is judged that the state is abnormal, an alarm signal is sent out, if no vehicle exists, whether the total charging duration exceeds the set duration T0 or not is judged, and if yes, a charging stopping instruction is sent out; if not, fault judgment is carried out according to the change parameters of the voltage along with time, and when the abnormal state