Fault indicator having increased sensitivity to fault currents
First Claim
1. A fault indicator responsive to the occurrence of a fault current at or above a predetermined minimum threshold level in an alternating current conductor, comprising, in combination:
- a housing including means for attaching the housing to the conductor;
indicator means within said housing having a reset-indicating state and a fault-indicating state;
electric circuit means within said housing for conditioning said indicator means to said fault-indicating state in response to a contact closure;
first and second magnetic reed switch elements arranged in parallel-spaced relationship to respective parallel-spaced planes each generally perpendicular to the axis of said conductor, said switch elements being in magnetic communication with said conductor and each including a pair of contacts actuated only upon the occurrence of a current in said conductor in excess of said predetermined threshold level;
said magnetic reed switch elements each including an elongated housing having magnetically and electrically conductive wire leads extending from the ends thereof;
the lead on one end of said first switch elements being electrically and magnetically connected to the lead on the adjacent end of said second switch elements, the remaining leads of said switch elements being arranged in parallel-spaced relationship to each other and to the axis of said switch elements;
a magnetically non-conductive and electrically conductive bridging element connected between said parallel-spaced switch leads, said circuit means being connected to said bridging element and to said connected leads whereby said indicator means are conditioned to a fault indicating state upon closure of either of said contacts of said switch elements; and
permanent magnet means mounted with the opposing poles thereof in communication with respective ones of said parallel spaced leads for establishing a magnetic bias circuit which serially includes said contacts of said magnetic switch elements, whereby said switch elements actuate upon the occurrence of a fault current at or above said threshold level during respective half cycles of the alternating current in the conductor, and return to a non-actuated state following termination of the fault current.
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Accused Products
Abstract
A fault indicator for indicating the occurrence of a fault current in an alternating current conductor includes a pair of parallel-spaced reed switches in magnetic communication with the conductor. The reed siwtches are electrically connected in parallel by a magnetically conductive bridging element at one end of the pair and by a non-magnetically conductive bridging element at the other end of the pair. A permanent magnet bridging the non-magnetic bridge establishes a magnetic bias circuit which extends serially through the switches to increase the sensitivity of each switch to a fault current during a respective half-cycle of the alternating current cycle.
43 Citations
14 Claims
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1. A fault indicator responsive to the occurrence of a fault current at or above a predetermined minimum threshold level in an alternating current conductor, comprising, in combination:
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a housing including means for attaching the housing to the conductor; indicator means within said housing having a reset-indicating state and a fault-indicating state; electric circuit means within said housing for conditioning said indicator means to said fault-indicating state in response to a contact closure; first and second magnetic reed switch elements arranged in parallel-spaced relationship to respective parallel-spaced planes each generally perpendicular to the axis of said conductor, said switch elements being in magnetic communication with said conductor and each including a pair of contacts actuated only upon the occurrence of a current in said conductor in excess of said predetermined threshold level; said magnetic reed switch elements each including an elongated housing having magnetically and electrically conductive wire leads extending from the ends thereof; the lead on one end of said first switch elements being electrically and magnetically connected to the lead on the adjacent end of said second switch elements, the remaining leads of said switch elements being arranged in parallel-spaced relationship to each other and to the axis of said switch elements; a magnetically non-conductive and electrically conductive bridging element connected between said parallel-spaced switch leads, said circuit means being connected to said bridging element and to said connected leads whereby said indicator means are conditioned to a fault indicating state upon closure of either of said contacts of said switch elements; and permanent magnet means mounted with the opposing poles thereof in communication with respective ones of said parallel spaced leads for establishing a magnetic bias circuit which serially includes said contacts of said magnetic switch elements, whereby said switch elements actuate upon the occurrence of a fault current at or above said threshold level during respective half cycles of the alternating current in the conductor, and return to a non-actuated state following termination of the fault current. - View Dependent Claims (2, 3)
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4. A fault indicator responsive to the occurrence of a fault current at or above a predetermined minimum threshold level in an alternating current conductor, comprising, in combination:
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a housing including means for attaching the housing to the conductor; indicator means within said housing having a reset-indicating state and a fault-indicating state; electric circuit means within said housing for conditioning said indicator means to said fault-indicating state in response to a contact closure; a circuit board arranged within said housing generally perpendicular to a radius of said conductor; first and second magnetic reed switch elements arranged in parallel-spaced relationship on one side of said circuit board in respective parallel-spaced planes each generally perpendicular to the axis of said conductor, said switch elements being in magnetic communication with said conductor and each including a pair of contacts actuated only upon the occurrence of a fault current in said conductor in excess of said predetermined threshold level; said magnetic reed switch elements each including an elongated housing having magnetically and electrically conductive wire leads extending from the ends thereof; said leads of said reed switch elements passing through respective apertures in said circuit board to the opposite side thereof, the lead on one end of said first switch element being electrically and magnetically connected to the lead on the adjacent ends of said second switch element, the remaining leads of said switch elements being each folded back along the rear surface of said circuit board in parallel-spaced relationship to each other and to the axis of said switch elements; a magnetically non-conductive and electrically conductive bridging elements connected between said parallel spaced switch leads, said circuit means being connected to said bridging element and to said connected leads whereby said indicator means are conditioned to a fault indicating state upon closure of either of said contacts of said switch elements; and permanent magnet means mounted to the underside of said circuit board with the opposing poles thereof in communication with respective ones of said parallel-spaced leads for establishing a magnetic bias circuit which serially includes said contacts of said magnetic switch elements, whereby said switch elements are actuated upon the occurrence of a fault current at or above said threshold level during respective half cycles of the alternating current in the conductor and revert to a non-actuated state upon termination of the fault current.
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5. A fault indicator responsive to the occurrence of a fault current at or above a predetermined minimum threshold level in an associated alternating current conductor, comprising, in combination:
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a housing; indicator means within said housing having a fault-indicating state and a reset-indicating state; electric circuit means including first and second magnetic switch elements in magnetic communication with said conductor and in parallel circuit configuration for conditioning said indicating means to said fault-indicating state upon actuation of either switch element, said switch elements actuating only in response to occurrence of a current in the conductor greater than the predetermined threshold level; and magnetic circuit means including a permanent magnet for establishing a magnetic bias circuit serially including said magnetic switch elements whereby said switch elements actuate upon the occurrence of a fault current at or above said threshold level during respective half cycles of the alternating current in the conductor, and return to a non-actuated state following termination of the fault current. - View Dependent Claims (6, 7, 8)
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9. A fault indicator responsive to the occurrence of a fault current in an associated alternating current conductor at or above a predetermined minimum threshold level, comprising, in combination:
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a housing; indicator means within said housing having a reset-indicating state and a fault-indicating state; circuit means including first and second magnetic switch elements in magnetic communication with said conductor and each actuated only upon the occurrence of a current in the conductor in excess of said predetermined threshold level for conditioning said indicating means to said fault indicating state, said switch elements being generally arranged in a parallel-spaced configuration in respective planes; and magnetic circuit means including an electrically magnetically conducting bridging means between adjacent ends of said switch elements, magnetically non-conductive and electrically conductive bridging means across the other adjacent ends of said switch elements, and permanent magnet means for inducing a magnetic field between said other adjacent ends, for establishing a magnetic bias circuit serially including said magnetic switch elements, whereby said switch elements actuate upon the occurrence of a fault current at said threshold level during respective half cycles of the alternating current in the conductor, and return to a non-actuated state upon termination of the fault current. - View Dependent Claims (10)
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11. A magnetic switch assembly responsive to the occurrence of a fault current in an associated alternating current conductor at or above a predetermined minimum threshold level, comprising, in combination:
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means including first and second magnetic switch elements in magnetic communications with the conductor and operable only upon the occurrence of a current in the conductor in excess of said predetermined threshold level; and magnetic circuit means including a permanent magnet for establishing a magnetic bias circuit serially including said magnetic switch elements whereby said switch elements actuate upon the occurrence of a fault current at said threshold level during respective half-cycles in the conductor, and return to a non-actuated state following termination of the fault current. - View Dependent Claims (12)
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13. A magnetic switch assembly responsive to the occurrence of a fault current in an alternating current conductor at or above a predetermined minimum threshold level, comprising, in combination:
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circuit means including first and second magnetic switch elements in magnetic communication with said conductor and each actuated only upon the occurrence of a current in the conductor in excess of said predetermined threshold level for conditioning said indicating means to said fault-indicating state, said switch elements being arranged in a parallel-spaced configuration; and magnetic circuit means including an electrically and magnetically conducting bridging means between adjacent ends of said switch elements, magnetically non-conductive and electrically conductive bridging means across the other adjacent ends of said switch elements, and permanent magnet means for inducing a magnetic field between said other adjacent ends, for establishing a magnetic bias circuit serially including said magnetic switch elements whereby said switch elements actuate upon the occurrence of a fault current at said threshold level during respective half cycles of the alternating current in the conductor, and return to a non-actuated state following termination of the fault current. - View Dependent Claims (14)
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Specification