Ground-safety controller
AssigneeDaniel J. Bondy
InventorLucas G. Lawrence
Life of this patent
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Abstract
A ground fault interrupter circuit is disclosed, comprising a high-voltage input from a public utility transformer, polarity reversal means coupled to the high-voltage input with polarity-switchable output coupled through a thyristor to a relay means. Radio frequency (RF) detection means are coupled to the thyristor gate, causing the thyristor to energize the relay and interrupt load power when radio frequency interference is detected from the load. The RF detector means comprises a plurality of RF chokes and resistor-capacitor pairs feeding a rectifier diode coupled to the thyristor gate. When RF is detected, the diode feeds negative direct current to the thyristor gate, interrupting conduction of the thyristor and the LOAD.
Claims25
A ground fault interrupter circuit comprising:
- a source of electric power provided on hot, neutral, and ground lines;
- a polarity reversal means coupled to the source of electric power for selectively providing a polarity-switched output on a plurality of output terminals;
- relay means for interrupting power from the source of electric power to a load, the relay being coupled through a thyristor to the output terminals;
- radio frequency (RF) interference detection means coupled from the source to the thyristor for interrupting conduction of the thyristor in response to RF interference from the load;
- and
- wherein the RF interference detection means comprises a high-impedance safety path, having an impedance which is a function of radio frequency signals, coupled from the ground line to a gate of the thyristor.
The circuit of claim wherein the high-impedance safety path comprises at least one resistor and a capacitor coupled in series from the ground line to the gate of the thyristor.
A ground fault interrupter circuit comprising:
- a source of electric power provided on hot, neutral, and ground lines:
- switch means coupled to the source of electric power for selectively providing a polarity-switched output on a plurality of output terminals, the switch means having first and second input terminals respectively coupled to the hot and neutral lines, third and fourth input terminals respectively coupled to the neutral and hot lines, and first and second output poles selectively connectable either to the first and second input terminals or to the third and fourth input terminals;
- relay means for interrupting power from the source of electric power to a load, the relay being coupled through a thyristor to the output terminals, the relay means comprising a relay coil coupled to double-pole, double-throw contacts;
- radio frequency (RF) interference detection means comprising:
- a high-impedance safety path, having an impedance which is a function of radio frequency signals, coupled from the ground line to a gate of the thyristor, comprising at least one high-impedance resistor and capacitor coupled from the ground line to the gate of the thyristor;
- and
- a diode coupled from the gate to the high-impedance safety path.
Dependencies are inferred from the claim text.