Safety device for preventing electric shock

Claim 2

In a single-phase, two-conductor current supply system wherein a pair of conductors are adapted to supply a current to a load, one of said conductors being at a high potential with respect to ground, and the other being at a relatively low potential with respect to ground, the combination comprising: signal responsive means for interrupting current in the conductor which is at a high potential with respect to ground, and means responsive to a predetermined change in the potential difference between the other conductor and ground, resulting from a fault between the conductor at high potential and ground, for providing a signal to effect interruption by said interrupting means when said predetermined change occurs.

Claim 3

In a single-phase, two-conductor current supply system wherein a pair of conductors are adapted to supply a current to a load, one of said conductors being at a high potential with respect to ground, and the other being at a relatively low potential with respect to ground, the combination comprising: signal responsive means for interrupting current in the conductor which is at a high potential with respect to ground, means connected between the other conductor and ground for conducting a current resulting from said relatively low potential difference, and means for sensing the current in said conducting means and providing a signal to effect interruption by said interrupting means when a predetermined change occurs in the current in said conducting means resulting from a fault between the conductor at hIgh potential and ground.

Claim 4

In a single-phase, two-conductor current supply system wherein a pair of conductors are adapted to supply a current to a load, one of said conductors being at a high potential with respect to ground, and the other being at a relatively low potential with respect to ground, the combination comprising: signal responsive means for interrupting current in the conductor which is at a high potential with respect to ground, means connected between the other conductor and ground for conducting a current resulting from said relatively low potential difference, and means for sensing the current in said conducting means and providing a signal to effect interruption by said interrupting means when a predetermined change occurs in the current in said conducting means resulting from a fault between the conductor at hIgh potential and ground.

Claim 5

The combination according to claim 2 in which said means for sensing the current in said conducting means comprises switching means, means for effecting opening of said switching means when said predetermined change occurs, and a relay having a winding connected to be energized through said switching means and normally closed contacts connected to conduct current to said signal-responsive means.

Claim 6

A safety device for preventing electric shock comprising: signal-responsive breaker means for effecting interruption of current in at least one of a group of conductors, said breaker means including manually operable resetting means allowing interruption of current in response to a signal even though said resetting means is held, means for sensing a ground fault in said one of said conductors and providing a signal to effect interruption, by said breaker, of current in said conductor, and means responsive to a closing of said breaker means for preventing said signal from being provided during a period of time immediately following said closing.

Claim 7

A safety device for preventing electric shock comprising: signal-responsive breaker means for effecting interruption of current in at least one of a group of conductors, said breaker means including manually operable resetting means allowing interruption of current in response to a signal even though said resetting means is held, means for sensing a ground fault in said one of said conductors and providing a signal to effect interruption, by said breaker, of current in said conductor, and means responsive to a closing of said breaker means for preventing said signal from being provided during a period of time immediately following said closing.

Claim 8

A safety device according to claim 4, in which said means for sensing a ground fault includes first switching means for conducting said signal to said signal responsive breaker means when a ground fault occurs, and said means responsive to a closing of said breaker means includes second switching means connected in series with said first switching means and means for preventing closing of said second switching means a period of time immediately following the closing of said breaker means.

Claim 9

A safety device according to claim 4, in which said means responsive to a closing of said breaker means comprises a delayed-action relay having contacts connected to conduct said signal to said signal responsive breaker means.

Claim 10

A safety device according to claim 4, in which said means responsive to a closing of said breaker means comprises a relay having contacts connected to conduct said signal to said signal responsive breaker means, said relay having a winding connected through a diode and resistive means to be energized when said breaker means is closed, and a capacitor connected across the winding of said relay.

Claim 11

A single-phase, two-conductor current supply system wherein a pair of conductors are adapted to supply a current to a load, one of said conductors being at a high potential with respect to ground, and the other being at a relatively low potential with respect to ground, the combination comprising: signal-responsive breaker means for interrupting current in the conductor which is at a high potential with respect to ground, an inductor connected to conduct current between the ground and the conductor which is at a low potential with respect to ground, a reed switch, a magnet arranged in proximity to said reed switch and normally biasing said reed switch into a closed condition, a relay connected to be operated through said reed switch and having a set of normally closed contacts which are held open when said reed switch is closed, means connected to said contacts for operating said signal responsive breaker means when said contacts close upon opening of said reed switch, said inductor being in proximity to said reed switch and arranged to overcome the bias imparted to said reed switch by said magnet when current, resulting from a ground fault, passes through said inductor.

Claim 12

A single-phase, two-conductor current supply system wherein a pair of conductors are adapted to supply a current to a load, one of said conductors being at a high potential with respect to ground, and the other being at a relatively low potential with respect to ground, the combination comprising: signal-responsive breaker means for interrupting current in the conductor which is at a high potential with respect to ground, an inductor connected to conduct current between the ground and the conductor which is at a low potential with respect to ground, a reed switch, a magnet arranged in proximity to said reed switch and normally biasing said reed switch into a closed condition, a relay connected to be operated through said reed switch and having a set of normally closed contacts which are held open when said reed switch is closed, means connected to said contacts for operating said signal responsive breaker means when said contacts close upon opening of said reed switch, said inductor being in proximity to said reed switch and arranged to overcome the bias imparted to said reed switch by said magnet when current, resulting from a ground fault, passes through said inductor.