Electronically controlled circuit breaker with integrated latch tripping

• US 5,946,179 A
• Filed: 03/25/1997
• Issued: 08/31/1999
• Est. Priority Date: 03/25/1997
• Status: Expired due to Term

• Current Assignee: Square D Company (Schneider Electric SE)
• Original Assignee: Square D Company (Schneider Electric SE)
• Inventors: Haun, Andy Allen, Fleege, Dennis W.
• Primary Examiner(s): Leja, Ronald W.
• Application Number:
  US08/827,031
• Time in Patent Office: 889 Days
• Field of Search: 361/42, 361/51, 361/54, 361/57, 361/58, 361/87, 361/93, 361/94, 361/99, 361/102, 361/114, 361/115, 335/21, 335/22, 335/23, 335/164, 335/166, 335/167, 335/170, 335/171, 335/172, 335/173, 335/174, 335/250, 335/251, 335/255, 335/18
• US Class Current: 361/42
• CPC Class Codes: G01R 31/1272 of cable, line or wire insulation, e.g. using partial discharge measurements locating faults in cables G01R31/083
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: H01H 2083/201 the other abnormal electrical condition being an arc fault
• CPC Class Codes: H01H 2089/005 Multi-purpose combinations, e.g. LS/DI, LS/FI, of normal protective circuit breakers with known other forms of protection, e.g. earthfaults, differential, unbalance
• CPC Class Codes: H01H 71/123 using a solid-state trip unit circuits H02H
• CPC Class Codes: H01H 71/505 Latching devices between operating and release mechanism
• CPC Class Codes: H02H 1/0015 Using arc detectors

Abstract

A circuit breaker for interrupting electrical current flowing through a line conductor to a load terminal in response to the detection of a current overload, ground fault and/or arcing fault. The circuit breaker has a trip circuit to generate a trip signal, a releasably latchable trip lever, and a latching mechanism. The trip lever is moveable between a latched position and a tripped position. In the latched position, the trip lever engages the latching mechanism and the electrical current flows through said circuit breaker. When a fault is detected by the trip circuit, a trip signal is send to the latching mechanism. Upon receiving the trip signal, the latching mechanism disengages the trip lever allowing the trip lever to slide into the tripped position and interrupting the current flow through the circuit breaker.

Claims

1. A circuit breaker for interrupting an electrical current in a branch circuit of an electrical distribution system, said circuit breaker comprising:

a pair of breaker contacts for opening and closing an electrical power distribution circuit,

a trip mechanism connected to at least one of said contacts for opening and closing said contacts,

a plurality of sensors coupled to said power distribution circuit for sensing the electrical current in said power distribution circuit, the sensors producing respective output signals each representing a characteristic of said current,

a plurality of separate electronic detectors each receiving a different one of the respective output signals, a first one of the detectors detecting occurrences of overload faults, a second one of the detectors detecting occurrences of ground faults and a third one of the detectors detecting occurrences of arcing faults, said detectors producing respective trip signals in response to such occurrences, and

an actuator for actuating said trip mechanism to open said contacts in response to said trip signals.

2. The circuit breaker of claim 1 wherein said circuit breaker is a non-industrial miniature circuit breaker.

3. The circuit breaker of claim 1 wherein said actuator is electromagnetically coupled directly to said power distribution circuit for responding immediately to an overload fault producing a current above a preselected level.

4. The circuit breaker of claim 1 wherein said actuator is a solenoid having a coil and a plunger concentric with said coil, said coil receiving said trip signal, and said plunger cooperating with said trip mechanism for latching and releasing said trip mechanism.

5. The circuit breaker of claim 1 wherein said plurality of separate electronic detectors includes means responsive to the current in said power distribution circuit for simulating the response of a conventional bimetallic strip sensor to a sustained overload fault.

6. The circuit breaker of claim 1 wherein said actuator comprises a single solenoid responsive to a trip signal produced in response to the occurrence of any of said overload fault, ground fault and arcing fault.

7. The circuit breaker of claim 6 which includes a line conductor looped around the coil of said solenoid for energizing said solenoid immediately in response to an overload fault producing a current above a preselected level in said line conductor.

8. The circuit breaker of claim 1 wherein the plurality of sensors includes an arcing fault sensor and a ground fault sensor electromagnetically coupled to the power distribution circuit and an overload sensor directly coupled to the power distribution circuit, the arcing fault sensor being coupled to a line conductor of the power distribution circuit and producing an output signal that is supplied to said third detector, the ground fault sensor being coupled simultaneously to a line and neutral conductor of the power distribution circuit and producing an output signal that is supplied to said second detector, the overload sensor comprising a portion of the first detector and producing an output signal that is supplied to the first detector.

9. The circuit breaker of claim 1 wherein the trip mechanism comprises:

a releasably latchable trip lever movable between a latched position and a tripped position, said electrical current adapted to flow through said circuit breaker when said trip lever is in said latched position, said electrical current being interrupted when said trip lever is moved to said tripped position; and

a latching mechanism moveable between an engaged position and a released position in response to receiving a trip signal, said latching mechanism being adapted to engage said trip lever in said latched position when in said engaged position, said trip lever being adapted to move from said latched position to said tripped position when said latching mechanism is moved to said released position.

10. The circuit breaker of claim 9 further including a line terminal, a line conductor and a load terminal, said electrical current flowing from said line terminal through said line conductor to said load terminal, a first one of said plurality of sensors being wrapped around said line conductor to monitor a rate-of-change of the electric current in said line conductor and to produce a signal representing said rate-of-change, the detector, for detecting arcing faults, being electrically connected to said first sensor to receive said rate-of-change signal and to produce said trip signal in response to said rate-of-change signal having characteristics of an arcing fault.

11. The circuit breaker of claim 9 further including a line terminal, a line conductor, a neutral conductor and a load terminal, said electrical current flowing from said line terminal through said line conductor to said load terminal, a second one of said sensors being wrapped around said line conductor and said neutral conductor to sense an imbalance of current flow between said line conductor and said neutral conductor and to produce a signal representing said imbalance of current flow, the second detector, for detecting ground faults, being electrically connected to said second sensor to receive said imbalance of current flow signal and to produce said trip signal in response to said imbalance of current flow signal having characteristics of a ground fault.

12. The circuit breaker of claim 9 further including a line terminal, a line conductor, a load terminal and a trip circuit, said electrical current flowing from said line terminal through said line conductor to said load terminal, said trip circuit taking a plurality of current samples from said line conductor and creating an accumulation of a square of said current samples, wherein said trip circuit produces said trip signal when said accumulation is greater than a predetermined threshold characterizing an overcurrent.

13. The circuit breaker of claim 9 wherein said-latching mechanism includes a moveable plunger and a coil, the plunger being adapted for movement relative to the coil in response to movement of said latching mechanism between said engaged and released positions, said coil creating a magnetic field when said latching mechanism is moved from said engaged position to said released position, the plunger having a first position in the coil when said latching mechanism is in said engaged position, the plunger being moved from said first position toward a second position further into the coil in response to creation of the magnetic field.

14. The circuit breaker of claim 13 further including a line terminal, a line conductor and a load terminal, said electrical current flowing from said line terminal through said line conductor to said load terminal, said line conductor forming a plurality of loops around said coil, a magnetic field being generated by said loops when said electric current increases above a threshold, said plunger being adapted to move into said coil in response to said magnetic field moving the latching mechanism from said engaged position to said released position.

15. The circuit breaker of claim 13 wherein said latching mechanism further includes a moveable latch plate having a seat end and a interlocking end, said interlocking end interlocking with a distal end of the plunger, said seat end engaging the trip lever in said latched position when said latching mechanism is in said engaged position, said trip lever being adapted to slide off said seat end in response to the plunger being moved into the coil.

16. The circuit breaker of claim 15 wherein said latching mechanism further includes a bias spring surrounding the plunger and having a first and second end, said first end of said bias spring abutting the interlocking end of the latch plate and said second end of said bias spring abutting the coil, said bias spring biasing the seat end of the latch plate into engagement with the trip lever when said latching mechanism is in said engaged position, said bias spring being adapted to compress between the coil and the interlocking end of the latch plate in response to the plunger being moved into the coil.

17. The circuit breaker of claim 15 wherein the latch plate includes a smooth jacket encasing a core, said core interlocking with said distal end of said plunger, said smooth jacket providing a smooth seat for said trip lever on said seat end of said latch plate in said latched position, said trip lever being adapted to slide off said smooth seat and move into said tripped position in response to the plunger being moved into the coil.

18. The circuit breaker of claim 15 wherein the seat end of the latch plate is smooth and rounded to provide a smooth seat for said trip lever on said seat end in said latched position, said trip lever being adapted to slide off said smooth seat and move into said tripped position in response to the plunger being moved into the coil.

19. The circuit breaker of claim 15 wherein the seat end of the latch plate is smooth and folded to provide a smooth seat for said trip lever in said latched position, said trip lever being adapted to slide off said smooth seat and move into said tripped position in response to the plunger being moved into the coil.

20. The circuit breaker of claim 15 wherein the interlocking end of the latch plate has a stop to limit the movement of the latch plate and the plunger, said stop abutting a breaker case when the latching mechanism is in the engaged position, said stop abutting the coil when the latching mechanism is in the released position.

21. The circuit breaker of claim 9 wherein said latching mechanism comprises a trip coil and a moveable armature, said movable armature seating said trip lever in said latched position when said latching mechanism is in said engaged position, said trip coil being adapted to create a magnetic field in response to said trip signal, said latching mechanism moving to said released position and said moveable armature releasing said trip lever in response to creation of the magnetic field.

22. The circuit breaker of claim 21 wherein said latching mechanism further includes a yoke, said trip coil being wrapped around said yoke and adapted to create said magnetic field around said yoke in response to said trip signal.

23. The circuit breaker of claim 13 wherein a distal end of said plunger seats the trip lever in the latched position when said latching mechanism is in said engaged position, said trip lever being adapted to slide off of said distal end and into said tripped position in response to the plunger being moved into said coil.

24. A circuit breaker for interrupting an electrical current in a branch circuit of an electrical distribution system, said circuit breaker comprising:

a pair of breaker contacts for opening and closing an electrical power distribution circuit,

a trip mechanism connected to at least one of said contacts for opening and closing said contacts, said trip mechanism including

a releasably latchable trip lever movable between a latched position and a tripped position, said electrical current adapted to flow through said circuit breaker when said trip lever is in said latched position, said electrical current being interrupted when said trip lever is moved to said tripped position; and

a latching mechanism moveable between an engaged position and a released position in response to receiving a trip signal, said latching mechanism being adapted to engage said trip lever in said latched position when in said engaged position, said trip lever being adapted to move from said latched position to said tripped position when said latching mechanism is moved to said released position;

means for electronically generating a trip signal; and

an actuator responsive to said trip signal for moving said latching mechanism between said engaged and released positions,

wherein said latching mechanism includes a moveable plunger, a coil and a moveable latch plate having a seat end and a interlocking end, the plunger being adapted for movement relative to the coil in response to movement of said latching mechanism between said engaged and released positions, the coil creating a magnetic field when said latching mechanism is moved from said engaged position to said released position, the plunger having a first position in the coil when said latching mechanism is in said engaged position, the plunger being moved from said first position toward a second position further into the coil in response to creation of the magnetic field, the interlocking end of the movable latch plate interlocking with a distal end of the plunger, the seat end of the latch plate having a first leg and a second leg defining a L-shape, said first leg providing a smooth seat for said trip lever in said latched position, said second leg being perpendicular to said first leg, the seat end of the movable latch plate engaging the trip lever in said latched position when said latching mechanism is in said engaged position, said trip lever being adapted to slide off said smooth seat and move into said tripped position in response to the plunger being moved into the coil.

25. A circuit breaker for interrupting an electrical current in a branch circuit of an electrical distribution system, said circuit breaker comprising:

a pair of breaker contacts for opening and closing an electrical power distribution circuit,

a trip mechanism connected to at least one of said contacts for opening and closing said contacts, said trip mechanism including

a releasably latchable trip lever movable between a latched position and a tripped position, said electrical current adapted to flow through said circuit breaker when said trip lever is in said latched position, said electrical current being interrupted when said trip lever is moved to said tripped position; and

a latching mechanism moveable between an engaged position and a released position in response to receiving a trip signal, said latching mechanism being adapted to engage said trip lever in said latched position when in said engaged position, said trip lever being adapted to move from said latched position to said tripped position when said latching mechanism is moved to said released position;

means for electronically generating a trip signal; and

an actuator responsive to said trip signal for moving said latching mechanism between said engaged and released positions,

wherein said latching mechanism includes a moveable plunger, a coil and a flexible latch plate having a seat end and a interlocking end, the plunger being adapted for movement relative to the coil in response to movement of said latching mechanism between said engaged and released positions, said coil creating a magnetic field when said latching mechanism is moved from said engaged position to said released position, the plunger having a first position in the coil when said latching mechanism is in said engaged position, the plunger being moved from said first position toward a second position further into the coil in response to creation of the magnetic field, said flexible latch plate having a relaxed position and a flexed position, said interlocking end of said latch plate interlocking with a distal end of the plunger, said seat end of said latch plate seating the trip lever in said latched position when said flexible latch plate is in said relaxed position, said trip lever being adapted to slide off said seat end of said latch plate in response to said flexible latch plate flexing into said flexed position when the plunger is moved into said coil.

26. The circuit breaker of claim 25 wherein the latch plate has a U shaped end for interlocking with the distal end of the plunger, said U-shaped end having a first leg and a second leg, said first leg interlocking with the distal end of the plunger, said second leg abutting the coil, said U-shaped end being movable between a relaxed position and a flexed position, the U-shaped end biasing said latch plate into engagement with said trip lever when in said relaxed position and compress between said plunger and said coil when in said flexed position.

27. The circuit breaker of claim 25 wherein the distal end of the latch plate comprises a first leg and a second leg movable relative to the trip lever between a relaxed position and a flexed position, said first leg abutting a breaker case, said second leg interlocking with said plunger, said first and second legs meeting at approximately a right angle and defining a seat for said trip lever when in said relaxed position, said first and second legs meeting at an obtuse angle and releasing said trip lever from said seat when in said flexed position.