Patent ID: 6888708

Claim:
A resistance grounded electrical system, comprising: an electrical system providing a power source and having a phase conductor, a neutral conductor and a ground conductor; a neutral grounding resistor having a high resistance selected such that the ground fault current flow from the ground conductor through the resistor to the neutral conductor is provided at a value equal to or slightly greater than the capacitive charging current of the system and no greater than about 25 amps; a ground fault detector having: a neutral input configured to be connected to the neutral conductor of the electrical system; a ground input configured to be connected to the ground conductor of the electrical system that connects to the neutral conductor through the neutral grounding resistor; a signal conditioning circuit connected to the neutral and ground inputs and adapted to provide a measure of an electrical parameter associated with current flowing through the neutral grounding resistor; an analog-to-digital converter configured to convert the measure to a digital signal; a user selectable input configured to select a neutral current value; a digital processor configured to received the digital signal from the analog-to-digital converter and the neutral current value from the user selectable input and configured to execute a program to determine whether a ground fault has occurred based upon the level of the digital signal and the neutral current value; and a pulse contactor configured to introduce pulses into the electrical system to allow the user to locate a ground fault location when a ground fault is detected.