Overcurrent relay circuit

Claim 2

An electric circuit for use in Controlling an electric current, comprising: means for receiving a sensed current; shorting means connected to the means for receiving the sensed current, said shorting means being responsive to an electrical condition of the sensed current; solid-state bi-directional switching means having a pair of main terminals and a gate, said shorting means being connected between one of said main terminals and the gate of the solid-state bi-directional switching means, said shorting means controlling said solid-state bi-directional switching means; capacitive means connected between the gate and the other of said main terminals of said solid-state bidirectional switching means, said capacitive means coupling transients from the other of said main terminals to the gate of the solid-state bi-directional switching means to maintain a conducting state through the solid-state bi-directional switching means during change in direction of the current between the main terminals; and means for connecting the solid-state bidirectional switching means to the electric current to be controlled.

Claim 3

An electric circuit as defined in claim 1 wherein the solid-state bi-directional switching means is a triac.

Claim 4

An electric circuit as defined in claim 1 wherein the shorting means includes a pair of transistors, said pair of transistors being connected between the gate and one of the main terminals of the solid-state bi-directional switching means.

Claim 5

An electric circuit as defined in claim 1 wherein the capacitive means includes a series resistance-capacitance circuit connected between the gate and the other of said main terminals of the solid-state bi-directional switching means.

Claim 6

An electric circuit as defined in claim 1 wherein the means for receiving a sensed current includes adjustable resistance means for determining the response level of the shorting means to the sensed current.

Claim 7

An electric circuit as defined in claim 1 wherein the means for receiving a sensed current includes rectifier and filter means connected to the shorting means, said rectifier and filter means supplying a D.C. signal to the shorting means.

Claim 8

An electric circuit as defined in claim 1 wherein the means for receiving a sensed current includes transformer means having a primary and a secondary winding, said transformer means receiving the sensed current at the primary winding and connected to the shorting means through the secondary winding, the transformer means being employed to provide isolation between the means for receiving the sensed current and the means for connecting the solid-state bi-directional switching means to the electric current to be controlled.

Claim 9

An electric circuit as defined in claim 1, including a varistor connected in parallel with the solid-state bi-directional switching means.

Claim 10

An electric circuit as defined in claim 1 wherein the shorting means includes time-delay means connected to the means for receiving the sensed current.

Claim 11

An electric circuit as defined in claim 1, including a Zener diode for determination of the response level of the shorting means to the sensed current.

Claim 12

An electric circuit as defined in claim 1 wherein the circuit includes indicator means connected to the solid-state bi-directional switching means, said indicator means displaying the state of conduction of the solid-state bi-directional switching means.

Claim 13

An electric circuit as defined in claim 1 wherein the shorting means includes a pair of transistors, and the solid-state bi-directional switching means is a triac.

Claim 14

An electric circuit as defined in claim 1 wherein the shorting means includes a pair of transistors, the solid-state bi-directional switching means is a triac, and the capacitive means is a series resistance-capacitance circuit.

Claim 15

An electric circuit as defined in claim 1, including adjustable resistance means and a Zener diode, said adjustable resistance means being connected to the Zener diode, said Zener diode being connected to the shorting meanS, said adjustable resistance means and said Zener diode acting in conjunction for determination of the response level of the shorting means to the sensed current.

Claim 16

An electric circuit as defined in claim 1 wherein the shorting means includes capacitive means connected to the means for receiving the sensed current, said capacitive means providing a time delay.

Claim 17

An electric circuit as defined in claim 1 wherein the shorting means includes a pair of identical transistors, said pair of identical transistors being connected between the gate and one of the main terminals of the solid-state bi-directional switching means.

Claim 18

An electric circuit for use in controlling an electric current, comprising: transformer means for receiving a sensed current, adjustable resistance means connected to said transformer means for adjusting the burden of the circuit; rectifier and filter means connected to the adjustable resistance means; a Zener diode connected to the rectifier and filter means; time-delay means connected to the Zener diode; transistor shorting means connected to the time-delay means, said transistor shorting means being responsive to the sensed current; a triac having a gate and a pair of main terminals, said transistor shorting means being connected between the gate and one of the main terminals of the triac, said transistor shorting means controlling the triac; capacitive means connected between the gate and the other of said main terminals of said triac, said capacitive means coupling transients from the other of said main terminals of the triac to the gate of the triac to maintain a conducting state through the triac during change in direction of the current between the main terminals; a varistor connected to the triac; indicator means connected to the triac for displaying the state of conduction of the triac; and output means connected to the triac for connection of the triac to the electric current to be controlled.

Claim 19

An electric circuit for use in controlling an electric current, comprising: transformer means for receiving a sensed current, adjustable resistance means connected to said transformer means for adjusting the burden of the circuit; rectifier and filter means connected to the adjustable resistance means; a Zener diode connected to the rectifier and filter means; time-delay means connected to the Zener diode; transistor shorting means connected to the time-delay means, said transistor shorting means being responsive to the sensed current; a triac having a gate and a pair of main terminals, said transistor shorting means being connected between the gate and one of the main terminals of the triac, said transistor shorting means controlling the triac; capacitive means connected between the gate and the other of said main terminals of said triac, said capacitive means coupling transients from the other of said main terminals of the triac to the gate of the triac to maintain a conducting state through the triac during change in direction of the current between the main terminals; a varistor connected to the triac; indicator means connected to the triac for displaying the state of conduction of the triac; and output means connected to the triac for connection of the triac to the electric current to be controlled.

Claim 20

An electric circuit for use in controlling an electric current, comprising: transformer means for receiving a sensed current; adjustable resistance means connected to said transformer means for adjusting the burden of the circuit; rectifier and filter means connected to the adjustable resistance means; a Zener diode connected to the rectifier and filter means; time-delay means connected to the Zener diode; transistor shorting means connected to the time-delay means, said transistor shorting means being responsive to the sensed current; a first triac having a gate and a pair of main terminals, said gate of the first triac being connected to the transistor shorting means; a second triac having a gate and a pair of main terminals, one of the main terminals of the first triac being connected to the gate of the second triac, and other of said main terminals of the first triac being connected to one of said main terminals of the second triac and the other of the main terminals of the second triac being connected to the transistor shorting means, said transistor shorting means controlling the first and second triacs; capacitive means connected between the gate of the first triac and one of said main terminals of the second triac, said capacitive means coupling transients from one of the main terminals of the second triac to the gate of the first triac to maintain a conducting state through the first and second triacs during change in direction of the current between the main terminals of the first and second triacs; a varistor connected to the second triac; indicator means connected to the second triac for displaying the state of conduction of the second triac; and output means connected to the second triac for connecting the second triac to the electric current to be controlled.

Claim 21

An electric circuit for use in controlling an electric current, comprising: transformer means for receiving a sensed current; adjustable resistance means connected to said transformer means for adjusting the burden of the circuit; rectifier and filter means connected to the adjustable resistance means; a Zener diode connected to the rectifier and filter means; time-delay means connected to the Zener diode; transistor shorting means connected to the time-delay means, said transistor shorting means being responsive to the sensed current; a first triac having a gate and a pair of main terminals, said gate of the first triac being connected to the transistor shorting means; a second triac having a gate and a pair of main terminals, one of the main terminals of the first triac being connected to the gate of the second triac, and other of said main terminals of the first triac being connected to one of said main terminals of the second triac and the other of the main terminals of the second triac being connected to the transistor shorting means, said transistor shorting means controlling the first and second triacs; capacitive means connected between the gate of the first triac and one of said main terminals of the second triac, said capacitive means coupling transients from one of the main terminals of the second triac to the gate of the first triac to maintain a conducting state through the first and second triacs during change in direction of the current between the main terminals of the first and second triacs; a varistor connected to the second triac; indicator means connected to the second triac for displaying the state of conduction of the second triac; and output means connected to the second triac for connecting the second triac to the electric current to be controlled.

Claim 22

An electric circuit for use in controlling an electric current, comprising: means for receiving sensed current; shorting means connected to the means for receiving the sensed current, said shorting means being responsive to an electrical condition of tHe sensed current; a first triac having a gate and a pair of main terminals, said gate of the first triac being connected to the shorting means; a second triac having a gate and a pair of main terminals, one of the main terminals of the first triac being connected to the gate of the second triac, the other of said main terminals of the first triac being connected to one of said main terminals of the second triac and the other of said main terminals of the second triac being connected to the shorting means, said shorting means controlling the first and second triacs, capacitive means connected between the gate of the first triac and one of said main terminals of the second triac, said capacitive means coupling transients from one of the main terminals of the second triac to the gate of the first triac to maintain a conducting state through the first and second triacs during change in direction of the current between the main terminals of the first and second triacs; and means for connecting the second triac to the electric current to be controlled.

Claim 23

An electric circuit for use in controlling an electric current, comprising: means for receiving sensed current; shorting means connected to the means for receiving the sensed current, said shorting means being responsive to an electrical condition of tHe sensed current; a first triac having a gate and a pair of main terminals, said gate of the first triac being connected to the shorting means; a second triac having a gate and a pair of main terminals, one of the main terminals of the first triac being connected to the gate of the second triac, the other of said main terminals of the first triac being connected to one of said main terminals of the second triac and the other of said main terminals of the second triac being connected to the shorting means, said shorting means controlling the first and second triacs, capacitive means connected between the gate of the first triac and one of said main terminals of the second triac, said capacitive means coupling transients from one of the main terminals of the second triac to the gate of the first triac to maintain a conducting state through the first and second triacs during change in direction of the current between the main terminals of the first and second triacs; and means for connecting the second triac to the electric current to be controlled.