Ground detection circuit for a three wire power supply
AssigneeHubbell Incorporated
InventorsMark Richard Walter, David Philip Eckel, Thomas James Batko
Life of this patent
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Abstract
A three wire power supply circuit is provided comprising a circuit for monitoring the integrity of the ground connection of the power supply circuit. A circuit element is provided in the line-to-ground current path which conducts when current flows in the line-to-ground current path and is nonconductive when the ground connection is poor or absent. A microcontroller monitors the output of the circuit element and operates a buzzer or a light emitting diode to indicate when the ground connection is poor or absent.
Claims18
An apparatus for monitoring a ground connection in a three wire power supply circuit which selectively connects and disconnects a load from an alternating current power source having line, neutral and ground conductors, said ground connection monitoring apparatus comprising:
- generating means for generating an output signal;
- control means connected between said line conductor and said ground conductor and connected to said generating means, said control means being configured to operate said generating means to generate said output signal when current flows between said line conductor and said ground conductor and to interrupt operation of said generating means when current does not flow between said line conductor and said ground conductor;
- and
- indicating means connected to at least one of said control means and said generating means and operable in response to said output signal to indicate at least one of the presence and the absence of current flow in said ground conductor.
An apparatus for monitoring a ground connection in a three wire power supply circuit which selectively connects and disconnects a load from an alternating current power source having line, neutral and ground conductors, said ground connection monitoring apparatus comprising:
- a generating circuit coupled to said line conductor and said ground conductor for generating an output signal when current flows between said line conductor and said ground conductor;
- a processor connected to said generating circuit and programmable to monitor the output of said generating circuit for the occurrence of said output signal;
- and
- an indicator connected to said processor, said processor being programmable to control said indicator to indicate a condition selected from the group consisting of the absence and presence of current flow in said ground conductor.
A method of monitoring a ground connection in three wire power supply circuit which selectively connects and disconnects a load from an alternating current power source having line, neutral and ground conductors, said method comprising the steps of:
- switching a circuit element in a current path comprising said line conductor and said ground conductor into a conducting state to generate an output signal when current flows through said current path, said circuit element operating in a nonconducting state and generation of said output signal being interrupted when current is not flowing through said current path;
- monitoring said circuit element for said output signal to determine when said circuit element is in a conducting state;
- and
- operating an indicator when said circuit element is in one of a conducting state and a nonconducting state.
Dependencies are inferred from the claim text.