Ground conductor monitoring system and method

Claim 1

In a power transmission system including a power source and a load and a plurality of power transmission cables extending between the power source and the load and further including a continuous, uninterrupted ground conductor extending between the source and load, and being directly connected to the source ground and directly connected to frame ground of the load, a monitoring system for monitoring electrical continuity of the ground conductor comprising a transmitter for transmitting a signal having a predetermined frequency within the audio range over the ground conductor, said transmitter signal being coupled to the ground conductor only through a closed inductive system comprising a first toroid surrounding said ground conductor, a receiver, said receiver being coupled to the ground conductor only through an additional closed inductive system comprising a second toroid surrounding said ground conductor and functioning to continuously receive said signal being carried over the ground conductor, said closed inductive system of said first and second toroids forming a closed system for monitoring continuity of said ground conductor so that possible parallel conductive paths which may extend from frame ground of the load to source ground cannot couple any signal to said receiver from said transmitter if said ground conductor is broken or open circuited, and whereby such possible parallel paths will not have any shunting effect on the receiver signal if the ground conductor is not open-circuited, and an alarm device associated with and actuated by said receiver to provide an indication when said revceiver no longer receives said signal, thereby indicating that an open circuit or high impedance condition exists in said ground conductor.

Claim 7

A method for monitoring continuity of a continuous, uninterrupted conductor extending between a power source and a load without directly connecting anything to the conductor to disturb its integrity comprising the steps of generating a continuous signal within the audio range, coupling the audio signal to the conductor through a first closed inductive system, and coupling a receiver to the conductor through a second closed inductive system whereby reception of the audio signal by the receiver is an indication of the continuity of the conductor and parallel conductive paths cannot couple any signal from the transmitter to the receiver to provide any erroneous indication of conductor continuity, and such parallel conductive paths cannot shunt the audio signal away from the receiver so as to provide any erroneous indication of conductor discontinuity.

Claim 8

A method for monitoring continuity of a continuous, uninterrupted conductor extending between a power source and a load without directly connecting anything to the conductor to disturb its integrity comprising the steps of generating a continuous signal within the audio range, coupling the audio signal to the conductor through a first closed inductive system, and coupling a receiver to the conductor through a second closed inductive system whereby reception of the audio signal by the receiver is an indication of the continuity of the conductor and parallel conductive paths cannot couple any signal from the transmitter to the receiver to provide any erroneous indication of conductor continuity, and such parallel conductive paths cannot shunt the audio signal away from the receiver so as to provide any erroneous indication of conductor discontinuity.