Ground-safety controller

Claim 2

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.

Claim 3

The circuit of claim 1, wherein the source of electric power is provided from a high-voltage alternating current public utility transformer.

Claim 4

The circuit of claim 1, wherein the ground line is coupled to auxiliary coupling means for providing a true earth ground.

Claim 5

The circuit of claim 1, wherein the polarity reversal means comprises 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.

Claim 6

The circuit of claim 1, wherein the polarity reversal means comprises a double-throw, double-pole switch.

Claim 7

The circuit of claim 5, wherein the switch comprises first and second input terminals coupled to the hot and neutral lines, the first and second input terminals being coupled to third and fourth input terminals using reverse polarity, and first and second output poles selectively connectable either to the first and second input terminals or to the third and fourth input terminals.

Claim 8

The circuit of claim 1, wherein the relay means comprises a relay coil coupled to double-pole, double-throw contacts.

Claim 9

The circuit of claim 1, further including a first fixed-value resistor coupling the polarity reversal means to a first terminal of the relay means, and wherein the thyristor is coupled from a second terminal of the relay means to the polarity reversal means.

Claim 10

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.

Claim 11

The circuit of claim 1, further including a diode coupled from the gate to the high-impedance safety path.

Claim 12

The circuit of claim 1, wherein the RF interference detection mean includes rectifier means coupled to the thyristor to feed negative direct current to the thyristor gate in response to RF interference generated by the load.

Claim 13

The circuit of claim 1, wherein the high impedance safety path comprises a network of a plurality of series-coupled resistor-capacitor pairs, each pair being coupled from one of the hot, neutral, and ground lines to the thyristor.

Claim 14

The circuit of claim 11 wherein the high impedance safety path comprises a network of a plurality of resistor-capacitor pairs, each pair being coupled from one of the hot, neutral, and ground lines to the thyristor via a diode rectifier.

Claim 15

The circuit of claim 1, wherein the radio frequency interference detection means comprises: an RF choke in each of the ground, hot, and neutral lines; a resistor-capacitor pair coupled from each of the hot, neutral, and ground lines to a diode, the diode being coupled to a gate of the thyristor.

Claim 16

The circuit of claim 1 the RF interference detection means being responsive to RF interference on the hot, neutral, or ground lines, and in response thereto, causing a rectifier to feed negative direct current voltage to the thyristor.

Claim 17

The circuit of claim 1, wherein the RF interference detection means includes rectifier means for triggering the thyristor and the relay means to interrupt power to the load in response to detection of RF interference on the hot, neutral, or ground lines.

Claim 18

The circuit of claim 12, wherein the RF interference detection means includes rectifier means for triggering the thyristor and the relay means to interrupt power to the load in response to detection by at least one of the capacitors of RF interference on the hot, neutral, or ground lines.

Claim 19

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.

Claim 20

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.

Claim 21

The circuit of claim 18, wherein the source of electric power is provided from a high-voltage alternating current public utility transformer.

Claim 22

The circuit of claim 18, wherein the ground line is coupled to auxiliary coupling means for providing a true earth ground.

Claim 23

The circuit of claim 18, wherein the switch means comprises a double-throw, double-pole switch.

Claim 24

The circuit of claim 18, further including a first fixed-value resistor coupling the switch means to a first terminal of the relay means, and wherein the thyristor is coupled from a second terminal of the relay means to the switch means.

Claim 25

The circuit of claim 18, the RF interference detection means being responsive to RF interference on the hot, neutral, or ground lines, and in response thereto, causing the diode to feed negative direct current voltage to the thyristor.

Claim 26

The circuit of claim 18, wherein the radio frequency interference detection means comprises: an RF choke in each of the ground, hot, and neutral lines; a resistor-capacitor pair coupled from each of the hot, neutral, and ground lines to said diode.

Claim 27

The circuit of claim 18, wherein the high impedance safety path comprises a network of a plurality of the resistor-capacitor pairs.