# US 5,710,513 A · Circuit breaker testing apparatus having adjustable inductor for controlling magnitude of current flow > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,710,513 A - Document ID: US5710513A - Status: Granted - Kind: A - Application number: 08/568,939 - Filed: 1995-12-07 - Granted: 1998-01-20 - Earliest claimed: 1995-12-07 - Inventors: James M. March - Web page: https://patentgrep.com/patent/US5710513A ## CPC - G01R 31/3277: {of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A circuit breaker testing apparatus includes an electrical circuit, an adjustable inductor connected in the circuit and a transducer for sensing current flow in the circuit. The circuit has leads terminated by electrical connectors for connection to terminals of a circuit breaker for providing a source of electrical power to circuit from the circuit breaker. The inductor is adapted to produce an adjustable electrical load on the circuit breaker. The testing apparatus also includes an indicator connected to the transducer for producing a reading of the magnitude of current flow in the circuit and for displaying and holding the reading of the highest magnitude of current flow reached in the circuit and thereby the magnitude of current flow at which the circuit breaker is tripped by the adjustment of the electrical load on the circuit breaker. A mechanism is provided for adjusting the inductor so as to reduce the electrical load produced on the circuit breaker and thereby increase the magnitude of current flow drawn through the circuit breaker circuit to cause tripping of the circuit breaker. The inductor includes a coil connected in the circuit and a ferromagnetic core being spaced apart and movable relative to the coil so as to continuously vary the impedance of the core to the flow of current in the circuit. ## Claims ### Claim 1 A circuit breaker testing apparatus, comprising: (a) an electrical circuit having leads terminated by electrical connectors for connection to terminals of a circuit breaker for providing a source of electrical power to said electrical circuit from the circuit breaker; (b) an adjustable inductor electrically connected in said electrical circuit for producing an adjustable electrical load on the circuit breaker; (c) means for sensing current flow in said electrical circuit; (d) indicator means electrically connected to said current sensing means for producing a reading of the magnitude of current flow in said electrical circuit and for displaying and holding the reading of the highest magnitude of current flow reached in said electrical circuit and thereby the magnitude of current flow at which the circuit breaker is tripped by the adjustment of the electrical load on the circuit breaker; and (e) means for adjusting said adjustable inductor so as to reduce the electrical load produced on the circuit breaker and thereby increase the magnitude of current flow drawn through the circuit breaker circuit to cause tripping of the circuit breaker. ### Claim 2 (depends on 1) The apparatus of claim 1 wherein said adjustable inductor includes: an electrical conductor coil electrically connected in said electrical circuit; and a ferromagnetic core spaced apart from said coil and being movable relative to said coil in first and second opposite directions so as to continuously vary the impedance to said flow of current through said coil in said electrical circuit until the circuit breaker is tripped. ### Claim 3 (depends on 2) The apparatus of claim 2 wherein said coil and core have respective axes extending in substantially parallel relation to one another and said core is movable relative to said coil along said axes. ### Claim 4 (depends on 1) The apparatus of claim 1 wherein said means for sensing said current flow in said electrical circuit includes a current transducer. ### Claim 5 (depends on 4) The apparatus of claim 4 wherein said indicator means includes a readout device electrically connected to said current transducer. ### Claim 6 (depends on 5) The apparatus of claim 5 wherein said indicator means further includes a direct current battery electrically connected to said readout device to provide a source of electrical power to operate said readout device. ### Claim 7 (depends on 5) The apparatus of claim 5 wherein said readout device is a digital display. ### Claim 8 (depends on 1) The apparatus of claim 1 wherein said adjusting means includes: a movable control knob; and a linkage connected to and extending between said control knob and said adjustable inductor such that selective moving of said control knob causes said linkage to adjust said adjustable inductor so as to decrease the impedance provided in said electrical circuit by said adjustable inductor and thereby increase the magnitude of current flow through said electrical circuit until the circuit breaker is tripped. ### Claim 9 (depends on 8) The apparatus of claim 8 wherein said linkage includes an insulator to prevent conduction of electricity from said adjustable inductor to said control knob. ### Claim 10 (depends on 8) The apparatus of claim 8 wherein said control knob is spring loaded to bias said adjustable inductor to a position at which said adjustable inductor produces a high impedance in said electrical circuit and thus a low magnitude of current flow in said electrical circuit. ### Claim 11 (depends on 1) The apparatus of claim 1 further comprising: an on/off switch electrically connected in said electrical circuit and being adapted to selectively open and close said electrical circuit. ### Claim 12 (depends on 1) The apparatus of claim 1 further comprising: (f) means for sensing current flow in an external electrical circuit connected to the circuit breaker in parallel with said electrical connectors of said electrical circuit of said apparatus such that the external electrical circuit provides a known normal electrical load on the circuit breaker and thus draws a known normal magnitude of current flow therethrough thereby requiring said adjustable inductor of said apparatus to only provide an electrical load sufficient to raise the magnitude of current flow from the known normal magnitude to a higher magnitude sufficient to cause tripping of the circuit breaker. ### Claim 13 A circuit breaker testing apparatus, comprising: (a) an electrical circuit having leads terminated by electrical connectors for connection to terminals of a circuit breaker for providing a source of electrical power to said electrical circuit from the circuit breaker; (b) an adjustable inductor electrically connected in said electrical circuit for producing an adjustable electrical load on the circuit breaker, said adjustable inductor including (i) an electrical conductor coil electrically connected in said electrical circuit, and (ii) a ferromagnetic core spaced apart from said coil and being movable relative to said coil in first and second opposite directions so as to continuously vary the impedance to said flow of current through said coil in said electrical circuit until the circuit breaker is tripped; (c) means for sensing current flow in said electrical circuit; (d) indicator means electrically connected to said current sensing means for producing a reading of the magnitude of current flow in said electrical circuit and for displaying and holding the reading of the highest magnitude of current flow reached in said electrical circuit and thereby the magnitude of current flow at which the circuit breaker is tripped by the adjustment of the electrical load on the circuit breaker; and (e) means for adjusting said adjustable inductor so as to reduce the electrical load produced on the circuit breaker and thereby increase the magnitude of current flow drawn through the circuit breaker circuit to cause tripping of the circuit breaker, said adjusting means including (i) a movable control member, and (ii) a linkage connected to and extending between said control member and said core of said adjustable inductor such that moving said control member causes said linkage to move said core relative to said coil in one of said first and second opposite directions to decrease the impedance provided in said coil by said core and thereby allow the magnitude of current flow through said electrical circuit to increase until the circuit breaker is tripped. ### Claim 14 (depends on 13) The apparatus of claim 13 wherein said coil and core have respective axes extending in substantially parallel relation to one another and said core is movable relative to said coil along said axes. ### Claim 15 (depends on 13) The apparatus of claim 13 wherein said means for sensing said current flow in said electrical circuit includes a current transducer. ### Claim 16 (depends on 13) The apparatus of claim 13 wherein said indicator means includes: a readout device electrically connected to said current transducer; and a direct current battery electrically connected to said readout device to provide a source of electrical power to operate said readout device. ### Claim 17 (depends on 16) The apparatus of claim 16 wherein said readout device is a digital display. ### Claim 18 (depends on 13) The apparatus of claim 13 wherein said linkage includes an insulator to prevent conduction of electricity from said core to said control knob. ### Claim 19 (depends on 13) The apparatus of claim 13 wherein said control member is a rotatable knob being spring loaded to bias said core to a position relative to said coil that produces a high impedance therein and thus a low magnitude of current in said electrical circuit. ### Claim 20 (depends on 13) The apparatus of claim 13 further comprising: an on/off switch electrically connected in said electrical circuit and being adapted to open and close said electrical circuit.