Ground-fault monitor for multiple circuits
First Claim
1. A ground fault monitor for an electrical system having a plurality of branch circuits each having a respective ground conductor extending to a service panel that includes a ground connection to which the ground conductors are electrically connected, comprising:
- a first ground bus electrically insulated from the service panel, wherein the ground conductors are connected to the first ground bus;
a second ground bus coupled to the ground connection;
a current transformer for sensing current flow through the plurality of ground conductors to the ground connection and generating a current flow signal representative of any sensed current flow;
an intermediate conductor extending from the first ground bus to the second ground bus wherein the current transformer senses current flow on the intermediate conductor; and
a monitoring circuit responsive to the current transformer for monitoring the current flow signal and generating an alarm when the current flow signal indicates the presence of a ground fault.
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Abstract
A ground fault monitor for an electrical system having a plurality of branch circuits each having a respective ground conductor extending to a service panel that includes a ground connection to which the ground conductors are electrically connected. The ground fault monitor includes a current transformer for sensing current flow through the plurality of ground conductors to the ground connection and generating a current flow signal representative of any sensed current flow, and a monitoring circuit responsive to the current transformer for monitoring the current flow signal and generating an alarm when the current flow signal indicates the presence of a ground fault.
44 Citations
15 Claims
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1. A ground fault monitor for an electrical system having a plurality of branch circuits each having a respective ground conductor extending to a service panel that includes a ground connection to which the ground conductors are electrically connected, comprising:
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a first ground bus electrically insulated from the service panel, wherein the ground conductors are connected to the first ground bus; a second ground bus coupled to the ground connection; a current transformer for sensing current flow through the plurality of ground conductors to the ground connection and generating a current flow signal representative of any sensed current flow; an intermediate conductor extending from the first ground bus to the second ground bus wherein the current transformer senses current flow on the intermediate conductor; and a monitoring circuit responsive to the current transformer for monitoring the current flow signal and generating an alarm when the current flow signal indicates the presence of a ground fault. - View Dependent Claims (2, 3, 4, 5)
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6. A ground fault monitoring system for an electrical system having a plurality of branch circuits each having a respective ground wire extending to a service panel, the system comprising:
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a first ground bus located at the service panel to which the branch circuit ground wires are electrically connected, wherein the first ground bus is electrically isolated from the service panel; an intermediate conductor electrically connecting the first ground bus to a ground connection at the service panel; wherein the ground connection at the service panel includes a second ground bus to which a neutral bus at the service panel is electrically connected; a ground fault monitoring circuit including; (i) a current transformer for measuring current flow on the intermediate conductor; and (ii) a monitoring circuit responsive to the current transformer for generating an alarm signal when the measured current flow exceeds a threshold. - View Dependent Claims (7, 8, 9, 10)
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11. A method for detecting a ground fault in an electrical circuit that includes a plurality of branch circuits each having a ground conductor connected to a first ground bus at a service panel, wherein the first ground bus is electrically isolated from the service panel;
- the first ground bus being connected by an intermediate conductor to a ground connection at the service panel, wherein the ground connection at the service panel includes a second ground bus to which a neutral bus at the service panel is electrically connected, including;
monitoring current flow on the intermediate conductor and generating an alarm signal when the current flow reaches a predetermined threshold that is indicative of a ground fault in any of the branch circuits. - View Dependent Claims (12, 13, 14, 15)
- the first ground bus being connected by an intermediate conductor to a ground connection at the service panel, wherein the ground connection at the service panel includes a second ground bus to which a neutral bus at the service panel is electrically connected, including;
Specification