Monitor system for ground fault relay

Claim 2

In a ground fault responsive protection system for operating a circuit interrupter of an electrical distribution system for opening the circuit interrupter upon the occurrence of a ground fault current of a pre-established level and comprising ground fault signal generating means for generating a ground fault signal having a signal level which varies with the ground fault current, electrical power source means, control means adapted to be energized by the electrical power source means and adapted while energized for being activated by a ground fault signal above a pre-established detection level for operating the circuit interrupter and a monitoring system for selectively testing the operation of the ground fault responsive protection system, the improvement wherein the monitoring system comprises first circuit means for connecting the electrical power source means for energizing the control means and having a reset switch operable for selectively deenergizing the control means, and second circuit means for alternatively connecting the electrical power source means to the signal generating means for generating a ground fault test signal above the pre-established detection level and connecting the circuit interrupter for being operated by the control means and having a second test switch manually operable between two operating positions thereof for providing said alternative connections.

Claim 3

A ground fault responsive protection system according to claim 1 wherein the reset switch and test switches are push button switches connected respectively for being depressed for deenergizing the control means and for connecting the electrical power source means to the signal generating means for generating said ground fault test signal.

Claim 4

A ground fault responsive protection system according to claim 1 wherein the second circuit means comprises manually settable control means for setting the ground fault test signal level for testing the pre-established detection level of the ground fault relay.

Claim 5

In a ground fault responsive protection system for operating a circuit interrupter of an electrical distribution system for opening the circuit interrupter upon the occurrence of a ground fault current of a pre-established level and comprising a ground fault sensor for generating a ground fault signal having a signal level which varies with the ground fault current, electrical power source means, a ground fault trip relay connected to the ground fault sensor and adapted to be energized by the Power source means and operable while energized to be activated by a ground fault signal above a pre-established detection level to operate the circuit interrupter, and a monitoring system for selectively testing the operation of the ground fault responsive protection system by selectively connecting the power source means for energizing the ground fault relay and for energizing the ground fault sensor for generating a ground fault test signal above the detection level, the improvement wherein the monitoring system comprises a first reset switch having a normal position for connecting the ground fault relay for being energized by the electrical power source means and operable for deenergizing the ground fault relay, and a second test switch having a first normal position for connecting the ground fault relay for operating the circuit interrupter and a second position for connecting the electrical power source means to the ground fault sensor for producing a ground fault test signal above the detection level, whereby by switching the second test switch from its first normal position to its second position the operation of the ground fault relay can be tested without opening the circuit interrupter and the operation of the circuit interrupter by the relay can then be tested by returning the second test switch to its first normal position without first operating the first reset switch for deenergizing the ground fault relay and such test operation of the circuit interrupter can be avoided by operating the first reset switch for deenergizing the ground fault relay and with the ground fault relay deenergized returning the second test switch to its normal position.

Claim 6

In a ground fault responsive protection system for operating a circuit interrupter of an electrical distribution system for opening the circuit interrupter upon the occurrence of a ground fault current of a pre-established level and comprising a ground fault sensor for generating a ground fault signal having a signal level which varies with the ground fault current, electrical power source means, a ground fault trip relay connected to the ground fault sensor and adapted to be energized by the Power source means and operable while energized to be activated by a ground fault signal above a pre-established detection level to operate the circuit interrupter, and a monitoring system for selectively testing the operation of the ground fault responsive protection system by selectively connecting the power source means for energizing the ground fault relay and for energizing the ground fault sensor for generating a ground fault test signal above the detection level, the improvement wherein the monitoring system comprises a first reset switch having a normal position for connecting the ground fault relay for being energized by the electrical power source means and operable for deenergizing the ground fault relay, and a second test switch having a first normal position for connecting the ground fault relay for operating the circuit interrupter and a second position for connecting the electrical power source means to the ground fault sensor for producing a ground fault test signal above the detection level, whereby by switching the second test switch from its first normal position to its second position the operation of the ground fault relay can be tested without opening the circuit interrupter and the operation of the circuit interrupter by the relay can then be tested by returning the second test switch to its first normal position without first operating the first reset switch for deenergizing the ground fault relay and such test operation of the circuit interrupter can be avoided by operating the first reset switch for deenergizing the ground fault relay and with the ground fault relay deenergized returning the second test switch to its normal position.

Claim 7

A ground fault responsive protection system according to claim 4 wherein the monitoring system comprises manually adjustable means for setting the level of the ground fault test signal for testing the detection level of the ground fault relay when the test switch is switched to generate a ground fault test signal.

Claim 8

A ground fault responsive protection system according to claim 4 wherein the reset and test switches are momentary contact, spring return switches adapted to be manually actuated for switching them from their normal positions.