Ground fault indicator
First Claim
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1. A ground fault indicator for indicating the occurrence of a ground fault current in multi-conductor electrical mains, comprising, in combination:
- magnetic circuit means comprising a helical magnetic pole piece having axially displaced ends encircling the conductors of the mains and forming a magnetic field between said axially displaced ends substantially parallel to the axis of said conductors dependent on the vector sum of the individual currents in the conductors;
magnetic sensing means disposed between said axially displaced ends and producing a control effect in response to said magnetic field exceeding a predetermined threshold level;
status indicating means having a reset-indicating state and a fault-indicating state; and
circuit means for conditioning said status indicating means to said fault-indicating state in response to said control effect.
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Abstract
A ground fault indicator for a multi-phase power distribution system includes a split-core magnetic pole assembly having a gap within which is developed a magnetic flux representative of the vector sum of the currents in the individual phase conductors of the system. A magnetic reed switch positioned within the gap responds to the summation current in the gap to trip an indicating circuit in a remotely mounted indicating module in the event of a ground fault.
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Citations
15 Claims
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1. A ground fault indicator for indicating the occurrence of a ground fault current in multi-conductor electrical mains, comprising, in combination:
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magnetic circuit means comprising a helical magnetic pole piece having axially displaced ends encircling the conductors of the mains and forming a magnetic field between said axially displaced ends substantially parallel to the axis of said conductors dependent on the vector sum of the individual currents in the conductors; magnetic sensing means disposed between said axially displaced ends and producing a control effect in response to said magnetic field exceeding a predetermined threshold level; status indicating means having a reset-indicating state and a fault-indicating state; and circuit means for conditioning said status indicating means to said fault-indicating state in response to said control effect. - View Dependent Claims (2, 3, 4, 5, 6, 15)
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7. A ground fault indicator for indicating the occurrence of a ground fault current in multi-conductor electrical mains, comprising, in combination:
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magnetic circuit means comprising a single turn helical-shaped magnetic pole piece having axiallly displaced ends encircling the conductors of the mains and having a gap between said axially displaced ends, the magnetic flux in said gap corresponding to the vector sum of the individual currents in the conductors said magnetic pole piece being positioned so that the magnetic field in said gap is aligned generally parallel with the axis of the conductors; magnetic switch means in magnetic communication with said gap and responsive to the magnetic flux within said gap for producing a control effect upon said flux exceeding a predetermined threshold level; status indicating means having a reset-indicating state and a fault-indicating state; and circuit means for conditioning said status indicating means to said fault indicating state in response to said ground fault current exceeding the predetermined threshold level. - View Dependent Claims (8, 9, 10, 11)
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12. A ground fault indicator for indicating the occurrence of a ground fault current in multi-conductor electrical mains, commprising, in combination:
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first and seconnd housings; magnetic circuit means comprising a single turn helical-shaped magnetic pole piece encircling the conductors of the mains and having axially displaced ends forming a gap therein, the magnetic flux in said gap corresponding to the vector sum of the individual currents in the conductors, said magnetic pole piece positioned so that the magnetic field within said gap is aligned generally parallel with the axis of the conductors; magnetic switch means within said first housing in magnetic communication with said gap and responsive to the magnetic flux therein for producing a control effect upon said flux exceeding a predetermined threshold level; status indicating means in said second housing remote from said first housing and viewable from the exterior of said second housing and having a reset-indicating state and a fault-indicating state; circuit means for conditioning said status indicating means to said fault indicating state in response to said ground fault current exceeding the predetermined threshold level; and means comprising a flexible cable extending between said first and second housings for connecting said magnetic switch means to said circuit means. - View Dependent Claims (13, 14)
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Specification