Ground fault circuit interrupter capable of deriving energy from ground fault current in order to achieve circuit interruption in the presence of a reduced supply voltage
First Claim
1. A ground-fault circuit interrupter interrupting the supply of electrical energy from a source to a load upon the occurrence of fault to ground, the interrupter comprising:
- first sensing means for detecting an imbalance of current in electrical conductors carrying power between the source and the load;
electrical circuit means connected to the first sensing means and responsive to a signal from the first sensing means to interrupt power to the load in response to a signal from the first sensing means; and
second sensing means responsive to a ground fault in the source to the load, the second sensing means capable of supplying power provided by a ground fault current to the electronic circuit to cause operation of the electronic circuit regardless of the presence of a reduced supply voltage to the electronic circuit.
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Accused Products
Abstract
A ground-fault circuit interrupter is provided with an additional current-sensing element that responds to a net value of current through the power wires in an ac circuit. The winding may be wound on a ferromagnetic core of its own or it may be placed as a separate winding on a core that is used to sense imbalance in a GFCI. In the latter case the extra winding must be insulated electrically from the main sense winding. The additional coil is connected to a rectifying diode and a capacitor, so that an imbalance of current in the power wires charges the capacitor. The voltage thus developed across the capacitor is used to operate the tripping mechanism of the ground-fault circuit interrupter. The fault-powered signal thus attained in the added winding will enable the GFCI to operate despite the existence of heavy fault currents that reduce the operating voltage to the rest of the GFCI to a level that would otherwise prevent its operation.
65 Citations
12 Claims
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1. A ground-fault circuit interrupter interrupting the supply of electrical energy from a source to a load upon the occurrence of fault to ground, the interrupter comprising:
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first sensing means for detecting an imbalance of current in electrical conductors carrying power between the source and the load; electrical circuit means connected to the first sensing means and responsive to a signal from the first sensing means to interrupt power to the load in response to a signal from the first sensing means; and second sensing means responsive to a ground fault in the source to the load, the second sensing means capable of supplying power provided by a ground fault current to the electronic circuit to cause operation of the electronic circuit regardless of the presence of a reduced supply voltage to the electronic circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A ground-fault circuit interrupter interrupting the supply of electrical energy from a source to a load upon the occurrence of a fault to ground, the interrupter comprising:
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first sensing means for detecting an imbalance of current in electrical conductors carrying power between the source and the load; electrical circuit means connected to the first sensing means and responsive to a signal from the first sensing means to interrupt power to the load in response to a signal from the first sensing means; and second sensing means responsive to a ground fault in the source to the load, the second sensing means capable of supplying power derived from the ground fault current for operation of the electronic circuit regardless of the presence of a reduced supply voltage to the electronic circuit. - View Dependent Claims (9, 10, 11)
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12. A ground fault circuit interrupter interrupting the supply of electrical energy from a source to a load upon the occurrence of a fault to ground, the interrupter comprising:
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first sensing means for detecting an imbalance of current in electrical conductors carrying power between the source and the load; a relay for operating contacts in series between the supply of electrical energy and said load, said relay operable by energization of a relay coil; means, responsive to said first sensing means, for de-energizing said relay coil in the event that said first sensing means detects said imbalance of current in electrical conductors carrying power between the source and the load; a first thyristor for controlling current flow to said relay coil, a second sense coil capable of having a current induced therein by an imbalance of current in electrical conductors carrying power between the source and the load; a second thyristor connected to extinguish conduction of said first thyristor when said second thyristor is in a conducting state, said second thyristor having a control element connected to said second sense coil, and said second thyristor capable of being driven into a conducting state by electric current flow between said second sense coil and said control element of said second thyristor, whereby a large fault to ground capable of reducing a supply voltage to the electronic circuit supplies current flow from said second sense coil to said second thyristor so as to de-energize said relay and interrupt the supply of electrical energy from said source to said load.
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Specification