Patent ID: 7583483

Claim:
A vehicle ground fault electrical detection system for a vehicle AC electrical system, the AC electrical system including an AC step-up voltage transformer having a primary coil and a secondary coil for increasing the voltage supplied to the transformer, the secondary coil being coupled to a secondary ground, the voltage supplied to the primary coil of the transformer being a converted voltage from a vehicle battery having a battery ground, the ground fault electrical detection system comprising: a fault detection circuit for detecting a short circuit between a secondary ground of the transformer and a battery ground, the fault detection circuit comprising: a resistance element having a predetermined resistance value, the resistance element having one side connected to a supply voltage; an electrical switching circuit connected to the resistance element for selectably coupling the other side of the resistance element to the secondary ground; a fault detection sense line connected to a junction between the other side of the resistance element and the electrical switching circuit; and a controller for selectably coupling the resistance element to the secondary ground, the controller being coupled to the fault detection sense line to receive a voltage signal for detecting the ground fault prior to a start-up of the AC step-up power transformation, the controller determining a ground fault based on a comparison responsive to the voltage signal and a predetermined comparative value.