Solid state circuit breaker

Claim 2

A solid state AC circuit breaker system having a pair of input terminals adapted to be coupled to an external power supply and a pair of output terminals adapted to be coupled to an external load, the system comprising: bilateral semi-conductor control means, impedence means coupled in series circuit relationship with said bilateral control means, one of said input terminals, and one of said output terminals, said bilateral control means having a gate electrode and having con-ductive and nonconductive states; trigger circuit means having input and output terminals, said trigger means having the input terminals thereof coupled to said impedence means whereby said trigger means provides an output signal which is a measure of current through said impedence means when said current exceeds a predetermined level; latching means coupled between an electrode of said bilateral control means and the gate electrode thereof, said latching means having a control electrode coupled to the output terminal of said trigger means, said latching means having conductive and nonconductive states, said latching means responsive to the output of said trigger means to change from its nonconducting to its conducting state; and a source of DC potential coupled to Said latching means and to the gate electrode of said bilateral control means, said DC source operative to bias said bilateral control means in its conductive state when said latching means is in its nonconductive state, said latching means in its conductive state operative to bias said bilateral control means in its nonconductive state.

Claim 3

The system set forth in claim 1 further including reset means coupled to said latching means for interrupting conduction through said latching means to restore conduction through said bilateral control means.

Claim 4

The system set forth in claim 1 further including switch means coupled in series with said latching means, said switch means being normally closed, said switch means when momentarily opened interrupting conduction through said latching means to restore conduction through said bilateral means.

Claim 5

The system set forth in claim 1 further including variable current control means coupled in series between the output terminal of said trigger means and the control electrode of said latching means whereby the current level at which said latching means changes from the non-conductive to the conductive state may be set.

Claim 6

The system set forth in claim 1 wherein said trigger circuit means includes a transformer having a primary and a secondary, said primary being coupled across said impedence means, and a full wave rectifier coupled across said secondary.

Claim 7

A solid state AC circuit breaker system having a pair of input terminals adapted to be coupled to an external power supply and a pair of output terminals adapted to be coupled to an external load, the system comprising: bilateral semi-conductor control means having an input electrode, an output electrode and a gate electrode, impedence means coupled in series with the output electrode of said bilateral control means and one of said output terminals, said bilateral control means having conductive and nonconductive states; trigger circuit means having input and output terminals, said trigger means having the input terminals thereof coupled to said impedence means whereby said trigger means provides an output signal which is a measure of current through said impedence means when said current exceeds a predetermined level; latching means coupled to said bilateral control means, said latching means comprising a silicon controlled rectifier (SCR) having anode, cathode, and gate electrodes, the anode of said SCR connected to the input electrode of said bilateral control means, the cathode of said SCR connected to the gate electrode of said bilateral control means, the gate electrode of said SCR connected to the output terminal of said trigger circuit means, said SCR being responsive to said output signal of said trigger means to change from a nonconducting to a conducting state; and a source of DC potential coupled across the anode and the cathode of said SCR and to the gate electrode of said bilateral control means, said DC source operative to bias said bilateral control means in its conductive state when said SCR is nonconductive, said SCR in its conductive state operative to bias said bilateral control means in its nonconductive state.

Claim 8

A solid state AC circuit breaker system having a pair of input terminals adapted to be coupled to an external power supply and a pair of output terminals adapted to be coupled to an external load, the system comprising: bilateral semi-conductor control means having an input electrode, an output electrode and a gate electrode, impedence means coupled in series with the output electrode of said bilateral control means and one of said output terminals, said bilateral control means having conductive and nonconductive states; trigger circuit means having input and output terminals, said trigger means having the input terminals thereof coupled to said impedence means whereby said trigger means provides an output signal which is a measure of current through said impedence means when said current exceeds a predetermined level; latching means coupled to said bilateral control means, said latching means comprising a silicon controlled rectifier (SCR) having anode, cathode, and gate electrodes, the anode of said SCR connected to the input electrode of said bilateral control means, the cathode of said SCR connected to the gate electrode of said bilateral control means, the gate electrode of said SCR connected to the output terminal of said trigger circuit means, said SCR being responsive to said output signal of said trigger means to change from a nonconducting to a conducting state; and a source of DC potential coupled across the anode and the cathode of said SCR and to the gate electrode of said bilateral control means, said DC source operative to bias said bilateral control means in its conductive state when said SCR is nonconductive, said SCR in its conductive state operative to bias said bilateral control means in its nonconductive state.