Direction sensing arc detection

• US 5,185,686 A
• Filed: 03/28/1991
• Issued: 02/09/1993
• Est. Priority Date: 03/28/1991
• Status: Expired due to Fees

• Current Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Hansen, James E., Beihoff, Bruce C., Tennies, Charles J., Richards, Francis S. Jr.
• Primary Examiner(s): Voeltz, Emanuel T.
• Assistant Examiner(s): BERHANE, ADOLF D
• Application Number:
  US07/676,840
• Time in Patent Office: 684 Days
• Field of Search: 361/5, 361/45, 361/46, 361/49, 361/50, 361/57, 361/63, 361/65, 361/67, 361/82, 361/84, 361/87, 361/91, 361/93, 361/111, 324/522, 324/529, 324/530, 324/536, 324/537, 324/541, 324/544
• US Class Current: 361/45
• CPC Class Codes: G01R 31/08 Locating faults in cables, transmission lines, or networks
• CPC Class Codes: H02H 1/0015 Using arc detectors

Abstract

An arc detection method and apparatus is provided for an electric circuit having an electrified conductor (46) connecting a voltage source (26) to a load (30), the conductor having a line side extending from the arc detector to the voltage source, and a load side extending from the arc detector to the load. The arc detector includes a field sensor (62) sensing the electromagnetic field established about the conductor by the occurrence of an electrical arc in the circuit, and generating a field responsive signal in response thereto. Direction sensing circuitry detects whether the arc is from the load side or the line side, and generates a direction indicative signal.

Claims

1. An arc detector for an electric circuit including an electrified conductor connecting a voltage source to a load, said conductor having a line side extending from said arc detector to said voltage source, and a load side extending from said arc detector to said load, said arc detector comprising a field sensor sensing an electromagnetic field established about said conductor by the occurrence of an electrical arc in said electric circuit, and generating a field responsive signal in response thereto, a direction sensing circuit detecting whether said electrical arc is from said load side or said line side and generating a direction indicative signal, an arc discrimination circuit responsive to said field sensor and generating an arc indicative signal in response to a given characteristic of said field responsive signal in combination with a given characteristic of said direction indicative signal, wherein said arc discrimination circuit comprises an AND circuit having a first input coupled to said field sensor, and a second input coupled to said direction sensing circuit, and having an output providing said arc indicative signal only if said arc is from said load side.

2. An arc detector for an electric circuit including an electrified conductor connecting a voltage source to a load, said conductor having a line side extending from said arc detector to said voltage source, and a load side extending from said arc detector to said load, said arc detector comprising a field sensor sensing an electromagnetic field established about said conductor by the occurrence of an electrical arc in said electric circuit, and generating a field responsive signal in response thereto, a direction sensing circuit detecting whether said electrical arc is from said load side or said line side and generating a direction indicative signal, wherein said direction sensing circuit comprises an inductor circuit connected in series between said line side and said load side, and a monitor circuit monitoring the voltage drop across said inductor circuit due to, said electrical arc wherein said voltage source has a predetermined excitation frequency, and comprising a high pass circuit coupled to said inductor circuit and said monitor circuit and selectively responding to frequencies higher than said predetermined excitation frequency, such that said monitor circuit monitors the voltage drop across said inductor circuit due to said electrical arc at frequencies higher than said predetermined excitation frequency.

3. An arc detector for an electric circuit including an electrified conductor connecting a voltage source to a load, said conductor having a line side extending from said arc detector to said voltage source, and a load side extending from said arc detector to said load, said arc detector comprising a field sensor sensing an electromagnetic field established about said conductor by the occurrence of an electrical arc in said electric circuit, and generating a field responsive signal in response thereto, a direction sensing circuit detecting whether said electrical arc is from said load side or said line side and generating a direction indicative signal, wherein said direction sensing circuit comprises an inductor circuit connected in series between said line side and said load side, and a monitor circuit monitoring the voltage drop across said inductor circuit due to, said electrical arc wherein said monitor circuit comprises a comparator circuit comparing the voltage at the line side of said inductor circuit against the voltage at the load side of said inductor circuit, and providing a load direction indicative signal if the voltage at the load side of said inductor circuit is higher than the voltage at the line of said inductor circuit, and providing a line direction indicative signal if the voltage at the load side of said inductor circuit is lower than the voltage at the line side of said inductor circuit.

4. An arc detector for an electric circuit including an electrified conductor connecting a voltage source to a load, said conductor having a line side extending from said arc detector to said voltage source, and a load side extending from said arc detector to said load, said arc detector comprising a field sensor sensing an electromagnetic field established about said conductor by the occurrence of an electrical arc in said electric circuit, and generating a field responsive signal in response thereto, a direction sensing circuit detecting whether said electrical arc is from said load side or said line side and generating a direction indicative signal, wherein said direction sensing circuit comprises an inductor circuit connected in series between said line side and said load side, and a monitor circuit monitoring the voltage drop across said inductor circuit due to, said electrical arc wherein said voltage source has a predetermined excitation frequency, and comprising a first capacitor coupled to said inductor circuit at the line side thereof, and a second capacitor coupled to said inductor circuit at the load side thereof, said first capacitor and said inductor circuit forming in combination a first filter attenuating propagation of signals from said load side through said inductor circuit at frequencies higher than said predetermined excitation frequency, said second capacitor and said inductor circuit forming in combination a second filter attenuating propagation of signals from said line side through said inductor circuit at frequencies higher than said predetermined excitation frequency.

5. The arc detector according to claim 4 comprising a frequency selective circuit comprising third and fourth capacitors, said third capacitor being coupled to the line side of said inductor circuit and to said first capacitor and passing said higher frequencies and blocking said predetermined excitation frequency, said fourth capacitor being coupled to the load side of said inductor circuit and to said second capacitor and passing said higher frequencies and blocking said predetermined excitation frequency.

6. The arc detector according to claim 5, comprising a first resistor connected in series with said third capacitor and forming an RC filter therewith, a second resistor connected in series with said fourth capacitor and forming an RC filter therewith, a fifth capacitor charged through said third capacitor and a third resistor, a sixth capacitor charged through said fourth capacitor and a fourth resistor, a fifth resistor coupled to said fifth capacitor for discharging said fifth capacitor, said fifth resistor having a higher resistance value than said third resistor such that said fifth capacitor discharges at a slower rate than it charges, a sixth resistor coupled to said sixth capacitor for discharging said sixth capacitor, said sixth resistor having a higher resistance value than said fourth resistor such that said sixth capacitor discharges at a slower rate than it charges, a comparator having a first input coupled to said sixth capacitor, a second input coupled to said fifth capacitor, and an output providing said direction indicative signal, and comprising first and second rectifying diodes, and wherein said fifth capacitor is charged to a DC level through said third capacitor, said first rectifying diode and said third resistor, and wherein said sixth capacitor is charged to a DC level through said fourth capacitor, said second rectifying diode, and said fourth resistor.

7. An arc detector for an electric circuit including an electrified conductor connecting a voltage source to a load, said conductor having a line side extending from said arc detector to said voltage source, and a load side extending from said arc detector to said load, said arc detector comprising a field sensor sensing an electromagnetic field established about said conductor by the occurrence of an electrical arc in said electric circuit, and generating a field responsive signal in response thereto, a direction sensing circuit detecting whether said electrical arc is from said load side or said line side and generating a direction indicative signal, wherein said field sensor comprises an E field sensor sensing an E field established about said conductor by the occurrence of an electrical arc in said electric circuit, wherein said field sensor further comprises in combination a B field sensor sensing a B field established about said conductor by the occurrence of an electrical arc in said electric circuit, wherein said field sensor further comprises in combination a B field sensor sensing a B field established about said conductor by the occurrence of an electrical arc in said electric circuit and generating a B field responsive signal, and comprising an arc discrimination circuit responsive to said E field sensor and to said B field sensor and to said direction sensing circuit and generating an arc indicative signal in response to a given characteristic of said E field responsive signal in combination with a given characteristic of said B field responsive signal and in further combination with a given characteristic of said direction indicative signal.

8. An arc detector for an electric circuit including an electrified conductor connecting a voltage source to a load, said conductor having a line side extending from said arc detector to said voltage source, and a load side extending from said arc detector to said load, said arc detector comprising a field sensor sensing an electromagnetic field established about said conductor by the occurrence of an electrical arc in said electric circuit, and generating a field responsive signal in response thereto, a direction sensing circuit detecting whether said electrical arc is from said load side or said line side and generating a direction indicative signal, an arc discrimination circuit responsive to said field sensor and generating an arc indicative signal in response to a given characteristic of said field responsive signal in combination with a given characteristic of said direction indicative signal, wherein said given characteristic of said field responsive signal is a random chaotic pattern of said field responsive signal.

9. The arc detector according to claim 8 wherein said arc discrimination circuit comprises a dual differentiate circuit differentiating said field responsive signal twice with respect to time to provide the second derivative of said field responsive signal for monitoring said random chaotic pattern of said field responsive signal to provide said arc indicative signal.

10. The arc detector according to claim 9 wherein said field sensor comprises an E field sensor sensing the E field established about said conductor by the occurrence of an electrical arc in said electric circuit and generating an E field responsive signal, and a B field sensor sensing a B field established about said conductor by the occurrence of an electrical arc in said electric circuit and generating a B field responsive signal, and wherein said arc discrimination circuit comprises a first dual differentiate circuit differentiating said E field responsive signal twice with respect to time to provide a second derivative of said E field responsive signal, a second dual differentiate circuit differentiating said B field responsive signal twice with respect to time to provide the second derivative of said B field responsive signal, such that said given characteristic of said field responsive signal is a random chaotic pattern of both said E field responsive signal and said B field responsive signal.

11. The arc detector according to claim 10 comprising an AND circuit having a first input from said first dual differentiate circuit, a second input from said second dual differentiate circuit, and a third input from said direction sensing circuit, and having an output providing said arc indicative signal.

12. An arc detector for an electrical current distribution circuit including a load center having a line side receiving electrical power from a voltage source of redetermined excitation frequency, and a load side distributing said electrical power to at least one load, said load center having at least one electro-responsive circuit breaker, and an electrified conductor coupling said voltage source through said load center and said circuit breaker to said load, said arc detector comprising a field sensor sensing an electromagnetic field established about said conductor y the occurrence of n electrical arc in said distribution circuit, and generating a field responsive signal in response thereto, a direction sensing circuit detecting whether said electrical arc is from said load side or said line side of said load center, a trip circuit responsive to said direction sensing circuit and tipping said circuit beaker to an open circuit condition if said arc is from said load side of said load center, and leaving said circuit breaker in a closed circuit condition if said arc is from said line side of said load center, wherein said direction sensing circuit comprises an inductor circuit connected in series between said line side and said load side, and a monitor circuit monitoring the voltage drop across said inductor circuit due to said arc, and comprising a frequency selective circuit coupled to said inductor circuit and said monitor circuit and selectively responding to frequencies higher than said predetermined excitation frequency, such that said monitor circuit monitors the voltage drop across pair a inductor circuit due to said electrical are at said higher frequencies, said monitor circuit comprising a comparator circuit comparing the voltage at the line side of said inductor circuit against the voltage at the load side of said inductor circuit at said higher frequencies, and triggering said trip circuit to trip said circuit breaker to said open circuit condition if the voltage at the load side of said inductor circuit is higher than the voltage at the line side of said inductor circuit at said higher frequencies, and leaving said circuit breaker in said closed circuit condition if the voltage at the load side of said inductor circuit is lower than the voltage at the line side of said inductor circuit at said higher frequencies, and comprising a first capacitor coupled to said inductor circuit at the line side thereof, and a second capacitor coupled to said inductor circuit at the load side thereof, said first capacitor and said inductor circuit forming in combination a first filter attenuating propagation of signals from said load side through said inductor circuit at frequencies higher than said predetermined excitation frequency, said second capacitor and said inductor circuit forming in combination a second filter attenuating propagation of signals from said line side through said inductor circuit at frequencies higher than said predetermined excitation frequency, and wherein said frequency selective circuit comprises third and fourth capacitors, said third capacitor being coupled to the line side of said inductor circuit and to said first capacitor and passing said higher frequencies and blocking said predetermined excitation frequency, said fourth capacitor being coupled to the load side of said inductor circuit and to said second capacitor and passing said higher frequencies and blocking said predetermined excitation frequency.

13. An arc detection method for an electric circuit including an electrified conductor connecting a voltage source to a load, said conductor having a line side extending from said voltage source, and a load side extending from said load, said arc detection method comprising sensing an electromagnetic field established about said conductor by the occurrence of an electrical arc in said electric circuit, and generating a field responsive signal in response thereof, detecting whether said arc is from said load side or said line side, and generating a direction indicative signal, discriminatingly responding to said field responsive signal and generating an arc indicative signal in response to a designed combination of a given characteristic of said field responsive signal and a given characteristic of said direction indicative signal, ANDing said field responsive signal and said direction indicative signal and providing said arc indicative signal only if said electrical arc is from said load side.

14. An arc detecting method for n electric circuit including an electrified conductor connecting a voltage source to a load, said conductor having a line side extending from said voltage source, and a load side extending from said load, said arc detection method comprising sensing an electromagnetic field established about said conductor by the occurrence of an electrical arc in said electric circuit, and generating a field responsive signal in response thereof, detecting whether said arc is from said load side or said line side, and generating a direction indicative signal, sensing an E field established about said conductor by the occurrence of an electrical arc in said electric circuit and generating an E field responsive signal, also sensing a B field established about said conductor by the occurrence of an electrical arc in said electric circuit and generating a B field responsive signal, discriminatingly responding to said E field responsive signal and to said B field responsive signal and to said direction indicative signal and generating an arc indicative signal in response to a given characteristic of said E field responsive signal in combination with a given characteristic of said B field responsive signal and further in combination with a given characteristic of said direction indicative signal.

15. An arc detection method for an electric circuit including an electrified conductor connecting a voltage source to a load, said conductor having a line side extending from said voltage source, and a load side extending from said load, said arc detection method comprising sensing an electromagnetic field established about said conductor by the occurrence of an electrical arc in said electric circuit, and generating a field responsive signal in response thereof, detecting whether said arc is from said load side or said line side, and generating a direction indicative signal, discriminatingly responding to said field responsive signal and generating an arc indicative signal in response to a designated combination of a given characteristic of said field responsive signal and a given characteristic of said direction indicative signal, generating said arc indicative signal in response to a random chaotic pattern of said field responsive signal.

16. The method according to claim 15, comprising differentiating said field responsive signal twice with respect to time to provide a second derivative of said field responsive signal for monitoring said random chaotic pattern of said field responsive signal to provide said arc indicative signal.

17. The method according to claim 16 comprising sensing the E field established about said conductor by the occurrence of an electrical arc in said electric circuit and generating an E field responsive signal, sensing the B field established about said conductor by the occurrence of an electrical arc in said electric circuit and generating a B field responsive signal, differentiating said E field responsive signal twice with respect to time to provide a second derivative of said E field responsive signal, differentiating said B field responsive signal twice with respect to time to provide a second derivative of said B field responsive signal, such that said given characteristic of said field responsive signal is a random chaotic pattern of both said E field responsive signal and said B field responsive signal.

18. The method according to claim 17 comprising ANDing said second derivative of said E field responsive signal and said second derivative of said B field responsive signal and said direction indicative signal to provide said arc indicative signal.