Claims
- 1. A molded case circuit breaker comprising:
- a housing having a base portion and a cover portion, said base portion formed with a plurality of spaced apart sidewalls for defining one or more phase compartments between contiguous sidewalls; each compartment having a first portion and a second portion;
- one or more pairs of separable main contacts, each pair carried by an upper contact arm and a line side conductor, disposed in a separate phase compartment, electrically coupled to line and load side conductors, said line side conductor carrying an insulation barrier;
- an operating mechanism operatively connected to said upper contact arm, disposed in said second portion of one of said phase compartments;
- one or more arc chutes disposed adjacent said separable main contacts in said first portion of said phase compartment; and
- means for supporting said sidewall against forces resulting from relatively high overcurrent conditions.
- 2. A molded case circuit breaker as recited in claim 1, wherein said supporting means also include means for providing a barrier between said first portion and said second portion of each of said phase compartments to reduce the amount of arc products resulting from a separation of the separable main contacts entering said second portion of said phase compartment.
- 3. A molded case circuit breaker as recited in claim 1, wherein said supporting means also includes means for securing said insulation barrier to said line side conductor.
- 4. A molded case circuit breaker as recited in claim 1, wherein said supporting means also includes means for capturing said arc chutes to prevent them from moving in a direction parallel to the longitudinal axis of the circuit breaker.
- 5. A molded case circuit breaker as recited in claim 1, wherein said supporting means is rigidly secured said line side conductor.
- 6. A molded case circuit breaker as recited in claim 1, wherein said supporting means is rigidly secured to said base.
- 7. A molded case circuit breaker as recited in claim 1, wherein said supporting means is carried by said line side conductor.
- 8. A molded case circuit breaker as recited in claim 1, wherein said barrier providing means is disposed between said first portion and said second portion of said phase compartment.
- 9. A molded case circuit breaker as recited in claim 8, wherein said barrier providing means is integrally formed with said supporting means.
- 10. A molded case circuit breaker as recited in claim 3, wherein said securing means is integrally formed with said supporting means.
- 11. A molded case circuit breaker as recited in claim 4, wherein said capturing means is integrally formed with said supporting means.
- 12. A molded case circuit breaker as recited in claim 1, wherein said supporting means includes elongated blocks disposed such that their longitudinal axes are generally parallel to the plane of the sidewalls.
- 13. A molded case circuit breaker as recited in claim 12, wherein said elongated blocks are disposed adjacent said sidewalls.
- 14. A molded case circuit breaker as recited in claim 13, wherein said elongated blocks are securely fastened to said line side conductor.
- 15. A molded case circuit breaker as recited in claim 14, wherein said elongated blocks are securely fastened to said base.
- 16. A molded case circuit breaker as recited in claim 12, wherein said elongated blocks extend substantially the height of said sidewalls.
- 17. A molded case circuit breaker as recited in claim 12, wherein said elongated blocks extend upwardly from said sidewalls.
- 18. A molded case circuit breaker as recited in claim 12, further including first means for connecting together said elongated blocks disposed in the same phase compartment.
- 19. A molded case circuit breaker as recited in claim 18, wherein said first connecting means includes a bridge member.
- 20. A molded case circuit breaker as recited in claim 19, wherein said bridge member is disposed substantially on the top of said elongated blocks.
- 21. A molded case circuit breaker as recited in claim 19, wherein said bridge member is integrally molded with two of said elongated blocks defining a C-shaped member.
- 22. A molded case circuit breaker as recited in claim 1, further including second means for connecting said supporting means to said sidewalls.
- 23. A molded case circuit breaker as recited in claim 22, wherein said second connecting means includes a dovetail connection formed by the sidewalls and the supporting means.
- 24. A molded case circuit breaker comprising:
- a housing having a base portion and a cover portion, said base portion formed with a plurality of spaced apart sidewalls for defining one or more phase compartments between contiguous sidewalls, each compartment having a first portion and a second portion;
- one or more pairs of separable main contacts carried by an upper contact arm and a line side conductor, each pair disposed in a separate phase compartment, electrically coupled to line and load side conductors, said line side conductor carrying an insulation barrier;
- an operating mechanism operatively connected to said upper contact arm, disposed in said second portion of one of said phase compartments;
- one or more arc chutes disposed adjacent said separable main contacts in said first portion of said phase compartment; and
- support block means disposed adjacent said sidewalls for supporting one of said sidewalls.
- 25. A molded case circuit breaker as recited in claim 24, wherein said support block means is an elongated arc block.
- 26. A molded case circuit breaker as recited in claim 25, wherein said elongated block has a key shaped projection along one side.
- 27. A molded case circuit breaker as recited in claim 26, wherein said one sidewall has a complementary key slot for receiving said key shaped projection to secure said elongated block to said sidewall.
- 28. A molded case circuit breaker as recited in claim 27, wherein said key shaped slot and said key shaped projection form a dovetail connection.
- 29. A molded case circuit breaker comprising:
- a housing having a base portion and a cover portion, said base portion formed with a plurality of spaced apart sidewalls for defining one or more phase compartments between contiguous sidewalls having a metallic plate disposed in the base portion adjacent each phase compartment, each compartment having a first portion and a second portion;
- one or more pairs of separable main contacts carried by upper contact arms and a line side conductors, each pair disposed in a separate phase compartment, electrically coupled to line and load side conductors, said line side conductor carrying an insulation barrier and having one or more insulated apertures;
- an operating mechanism operatively connected to said upper contact arm, disposed in said second portion of one of said phase compartments;
- one or more arc chutes disposed adjacent said separable main contacts in said first portion of said phase compartment; and
- elongated blocks disposed adjacent said sidewalls, each support block having a longitudinal bore for receiving a metallic fastener connected to said metallic plate through said insulated aperture in said line conductor forming a slot motor.
- 30. A molded case circuit breaker as recited in claim 29 wherein said blocks are disposed adjacent said sidewalls for supporting said sidewalls against forces resulting from relatively high overcurrent conditions.
- 31. A molded case circuit breaker as recited in claim 29, wherein said blocks form a barrier between said first portion and said second portion of each of said phase compartments to reduce the amount of arc products resulting from a separation of the separable main contacts from entering said second portion of said phase compartment.
- 32. A molded case circuit breaker as recited in claim 29, wherein said blocks also include means for securing said insulation barrier to said line side conductor.
- 33. A molded case circuit breaker as recited in claim 29, wherein said blocks also include means for capturing said arc chutes to prevent them from moving in a direction parallel to the longitudinal axis of the circuit breaker.
- 34. A molded case circuit breaker as recited in claim 29, wherein said blocks are disposed between said first portion and said second portion of said phase compartment.
- 35. A molded case circuit breaker as re cited in claim 32, wherein said securing means is integrally formed with said blocks.
- 36. A molded case circuit breaker as recited in claim 33, wherein said capturing means is integrally formed with said supporting means.
- 37. A molded case circuit breaker as recited in claim 29, wherein said blocks are disposed such that their longitudinal axes are generally parallel to the plane of the sidewalls.
- 38. A molded case circuit breaker as recited in claim 29, further including means for connecting said elongated blocks to said sidewalls.
- 39. A molded case circuit breaker as recited in claim 38, wherein said connecting means includes a dovetail connection formed by the sidewalls and the supporting means.
- 40. A molded case circuit breaker as recited in claim 29, wherein said elongated blocks are formed with key shaped projections along one side.
- 41. A molded case circuit breaker as recited in claim 40, wherein said sidewalls are formed with key slots for receiving said key shaped projections formed on said elongated blocks to secure said elongated blocks to said sidewalls.
- 42. A molded case circuit breaker as recited in claim 41, wherein said key slots and said key shaped projections form a dovetail connection.
- 43. A molded case circuit breaker comprising:
- a housing having a base portion and a cover portion, said base portion formed with a plurality of spaced apart sidewalls for defining one or more phase compartments between contiguous sidewalls having a metallic plate disposed in the base portion adjacent each phase compartment; each compartment having a first portion and a second portion;
- one or more pairs of separable main contacts, each pair carried by an upper contact arm and a line side conductor, disposed in a separate phase compartment, electrically coupled to line and load side conductors, said line side conductor carrying an insulation barrier and having one or more insulated apertures;
- an operating mechanism including a toggle assembly for actuating said one or more pairs of separable contacts, said operating mechanism operatively coupled to a cradle assembly and said upper contact arm disposed in said second portion of one of said phase compartments, said cradle assembly having a heat-treated portion defining latch and reset surfaces for latching and resetting said operating mechanism and a cradle portion coupled to said toggle assembly and means for securing said heat-treated portion to said cradle portion;
- one or more arc chutes disposed adjacent said separable main contacts in said first portion of said phase compartment; and
- elongated blocks disposed adjacent said sidewalls for supporting said sidewalls from forces resulting from relatively high overcurrent conditions; each block having a longitudinal bore for receiving a metallic fastener connected to said metallic plate through said insulated aperture in said line conductor forming a slot motor.
- 44. A molded case circuit breaker comprising:
- a housing having a base portion and a cover portion, said base portion formed with a plurality of spaced apart sidewalls for defining one or more phase compartments between contiguous sidewalls, each compartment having a first portion and a second portion;
- one or more pairs of separable main contacts carried by an upper contact arm and a line side conductor, each pair disposed in a separate phase compartment, electrically coupled to line and load side conductors, said line side conductor carrying an insulation barrier;
- an operating mechanism operatively connected to said upper contact arm, disposed in said second portion of one of said phase compartments;
- one or more arc chutes disposed adjacent said separable main contacts in said first portion of said phase compartment; and
- elongated support blocks disposed adjacent said sidewalls.
- 45. A molded case circuit breaker as recited in claim 44, wherein said elongated blocks are formed with key shaped projections along one side.
- 46. A molded case circuit breaker as recited in claim 45, wherein said sidewalls are formed with key slots for receiving said key shaped projections formed on said elongated blocks to secure said elongated blocks to said sidewalls.
- 47. A molded case circuit breaker as recited in claim 46, wherein said key slots and said key shaped projections form a dovetail connection.
- 48. A molded case circuit breaker, comprising:
- a housing, said housing having a plurality of spaced apart sidewalls for defining a phase compartment between contiguous sidewalls;
- a pair of separable main contacts, disposed in a said phase compartment;
- an operating mechanism operatively connected to open said separable main contacts; and
- supporting means for supporting said sidewall against forces resulting from relatively high overcurrent conditions, wherein said supporting means includes elongated blocks with a longitudinal axis disposed such that their longitudinal axes are generally parallel to the plane of the sidewalls.
- 49. A molded case circuit breaker, comprising:
- a housing, said housing having a plurality of spaced apart sidewalls for defining a phase compartment between contiguous sidewalls;
- a pair of separable main contacts, disposed in a said phase compartment;
- an operating mechanism operatively connected to open said separable main contacts; and
- supporting means for supporting said sidewall against forces resulting from relatively high overcurrent conditions; and
- an arc chute, wherein said supporting means also includes capturing means for capturing said arc chute to prevent substantial movement thereof.
- 50. A molded case circuit breaker, comprising:
- a housing, said housing having a plurality of spaced apart sidewalls for defining a phase compartment between contiguous sidewalls;
- a pair of separable main contacts, disposed in a said phase compartment;
- an operating mechanism operatively connected to open said separable main contacts; and
- supporting means for supporting said sidewall against forces resulting from relatively high overcurrent conditions,
- wherein said phase compartment has a first portion and a second portion wherein said supporting means also include barrier means for providing a barrier between said first portion and said second portion of said phase compartments to reduce the amount of arc products resulting from a separation of the separable main contacts from entering one portion of said phase compartment from another portion.
- 51. A molded case circuit breaker, comprising:
- a housing, said housing having a plurality of spaced apart sidewalls for defining a phase compartment between contiguous sidewalls;
- a pair of separable main contacts, disposed in a said phase compartment;
- an operating mechanism operatively connected to open said separable main contacts;
- supporting means for supporting said sidewall against forces resulting from relatively high overcurrent conditions; and
- connecting means for connecting said supporting means to said sidewalls.
- 52. A molded case circuit breaker as recited in claim 49, wherein said capturing means is integrally formed with said supporting means.
- 53. A molded case circuit breaker as recited in claim 50, wherein said elongated blocks are disposed adjacent said sidewalls.
- 54. A molded case circuit breaker as recited in claim 51, wherein said connecting means includes a dovetail connection formed by the sidewalls and the supporting means.
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part application of application Ser. No. 256,878, filed on Oct. 12, 1988 now abandoned.
The invention disclosed herein relates to molded case circuit breakers. The following seven patent applications all relate to molded case circuit breakers and were filed on Aug. 1, 1988: Ser. No. 226,500, entitled RUBBER STOPS IN OUTSIDE POLES, William E. Beatty, Jr., Lawrence J. Kapples, Lance Gula and Joseph F. Changle, Westinghouse Case No. WE-54,532; Ser. No. 226,648, entitled CT QUICK CHANGE ASSEMBLY, by Jere L. McKee, William E. Beatty, Jr. and Glenn R. Thomas, Westinghouse Case No. WE-54,533; Ser. No. 226,503, entitled CROSS-BAR ASSEMBLY, by Jere L. McKee, Lance Gula, and Glenn R. Thomas, Westinghouse Case No. WE-54,579; Ser. No. 226,649, entitled LAMINATED COPPER ASSEMBLY, by Charles R. Paton, Westinghouse Case No. WE-54,580; Ser. No. 226,650, entitled CAM ROLL PIN ASSEMBLY, by Lance Gula and Jere L. McKee, Westinghouse Case No. WE-54,594; Ser. No. 226,655, entitled COMBINATION BARRIER AND AUXILIARY CT BOARD by Gregg Nissly, Allen B. Shimp and Lance Gula, Westinghouse Case No. WE-54,821; Ser. No. 226,654, entitled MODULAR OPTION DECK ASSEMBLY by Andrew J. Male, Westinghouse Case No. WE-54,822.
The following four commonly assigned U.S. patent applications were filed on Oct. 12, 1988 and all relate to molded case circuit breakers: Ser. No. 256,881 entitled SCREW ADJUSTABLE CLINCH JOINT WITH BOSSES, by James N. Altenhof, Ronald W. Crookston, Walter V. Bratkowski, and J. Warren Barkell, Westinghouse Case No. WE-54,694; Ser. No. 256,879 entitled TAPERED STATIONARY CONTACT LINE COPPER, by Ronald W. Crookston, Westinghouse Case No. WE-54,695; Ser. No. 256,880, entitled SIDE PLATE TAPERED TWIST-TAB FASTENING DEVICE FOR FASTENING SIDE PLATES TO THE BASE, by K. Livesey and Alfred E. Maier, Westinghouse Case No. WE-54,715; Ser. No. 256,878, entitled TWO-PIECE CRADLE LATCH FOR CIRCUIT BREAKER, by Alfred E. Maier and William G. Eberts, Westinghouse Case No. WE-54,870.
The following commonly assigned U.S. patent applications also relate to molded case circuit breakers: Ser. No. 260,848, filed on Oct. 21, 1988 entitled UNRIVETED UPPER LINK SECUREMENT, by Joseph Changle and Lance Gula, Westinghouse Case No. WE-54,713I; Ser. No. 331,769, filed on Apr. 3, 1989 entitled ARC RUNNER, CONTAINMENT SUPPORT ASSEMBLY by Charles Paton, Kurt Grunert and Glen Sisson, Westinghouse Case No. WE-55,102; Ser. No. 331,920, filed on Mar. 31, 1989 entitled EXTENDER SPRING FOR INCREASED MAGNETIC TRIP SETTINGS, by Kurt Grunert, Westinghouse Case No. WE-55,015.
Lastly, the following patent application is being filed on even date herewith: Ser. No. 343,037, entitled TWO PIECE CRADLE LATCH, KEY BLOCKS AND SLOT MOTOR FOR CIRCUIT BREAKER, by Alfred E. Maier, William G. Eberts and Richard E. White, Westinghouse Case No. WE-54,870-I-1. White, William G. Eberts and Alfred E. Maier, Westinghouse Case No. WE-54,870-I-2.
1. Field of the Invention
This invention relates to molded case circuit breakers and more particularly to a two piece cradle latch having a non-heat-treated portion and a heat-treated portion defining latch and reset surfaces, securely fastened to the non-heat-treated cradle portion and to supports for bracing the sidewalls of the molded base against forces resulting from relatively high overcurrent conditions, such as a short circuit condition. In an alternate embodiment, slot motors are incorporated into the supports.
2. Description of the Prior Art
Molded case circuit breakers are generally old and well known in the art. Examples of such circuit breakers are disclosed in U.S. Pat. Nos. 4,489,295; 4,638,277; 4,656,444 and 4,679,018. Such circuit breakers are used to protect electrical circuitry from damage due to an overcurrent condition, such as an overload and relatively high level short circuit condition. An overload condition is normally about 200-300 percent of the nominal current rating of the circuit breaker. A high level short circuit condition can be 1000 percent or more of the nominal current rating of the circuit breaker.
Molded case circuit breakers include at least one pair of separable main contacts which may be operated either manually by way of a handle, disposed on the outside of the case, or automatically in response to an overcurrent condition. In the automatic mode of operation, the main contacts may be opened by an operating mechanism, controlled by an electronic trip unit, or by magnetic repulsion forces generated between the stationary and movable contacts during relatively high levels of overcurrent.
In one automatic mode of operation, the contact assemblies for all poles are tripped together by an electronic trip unit and a mechanical operating mechanism. More particularly, the electronic trip unit is provided with current sensors to sense an overcurrent condition. When an overcurrent condition is sensed, the current transformers provide a signal to the electronic circuitry within the electronic trip unit to actuate the operating mechanism to cause the main contacts to be separated.
In the other automatic mode or operation, the contact arm assemblies are disengaged from the mechanical operating mechanism and are blown open by magnetic repulsion forces. More particularly, magnetic repulsion members or shunts are used to allow the contact arm, which carries the movable main contact, to pivot. Each magnetic repulsion member is generally V-shaped defining two legs. During relatively high level overcurrent conditions, magnetic repulsion forces are generated between the legs of the magnetic repulsion member as a result of current flowing through the legs in opposite directions. At a relatively high level overcurrent condition, these magnetic repulsion forces cause the contact arm carrying the movable main contact to be blown open.
During a blow open condition, each contact arm is operated independently of the mechanical operating mechanism. For example, for a three phase circuit breaker having a high level overcurrent on the A phase; only the A phase contact arm will be blown open by its respective repulsion member. The contact arms for the B and C phases would remain closed and thus are unaffected by the operation of the A phase. The contact arms for the B and C phases are tripped by the electronic trip unit and the operating mechanism. This is done to prevent a condition known as single phasing, which can occur for circuit breakers connected to rotational loads, such as motors. In such a situation, unless all phases are tripped, the motor may act as a generator and contribute to the overcurrent condition.
The circuit breaker includes a cradle having latch and reset surfaces for latching and resetting the operating mechanism. Due to the wear on the latch and reset surfaces, these surfaces are often heat-treated. However, due to the complicated shape of the cradle having bends in many different directions, heat-treating can cause the cradle to become brittle and distort.
In a multi-phase molded case circuit breaker, each pole is compartmentalized in the base by way of sidewalls. These sidewalls are used to segregate the poles from one another and also for carrying the operating handle and the operating mechanism. In particular, in a three phase circuit breaker, two internal sidewalls are provided. The internal sidewalls along with the exterior walls of the base are used to form three compartments; two outside compartments and a center compartment. The outside compartments are formed from an exterior wall of the base and one interior sidewall. The center compartment is formed from the two interior sidewalls.
During a relatively high overcurrent condition, such as a short circuit condition, relatively large magnetic repulsion forces are developed. These magnetic repulsion forces are developed between various electrical current carrying components of the circuit breaker. Since such current carrying components are carried by the base of the circuit breaker and the sidewalls, the force between the current carrying components is transmitted to the sidewalls and the cover, attached to the base. Such forces can damage the sidewalls.
In known molded case circuit breakers, separate components are generally provided for each of the various design objectives which can make the cost of manufacturing the circuit breaker relatively more expensive. For example, each compartment in the base is generally provided with a barrier for preventing arc products resulting from the separation of the main contacts from attacking other components in the circuit breaker. In some known molded case circuit breakers, these barriers are generally integrally molded with the base. The barriers are disposed on opposing sidewalls of each compartment and spaced apart to allow free movement of the pivotally mounted contact arm.
The pivotally mounted contact arm which carries the movable main contact is generally insulated. The insulation keeps the arc resulting from the separation of the main contacts concentrated at the contacts, as opposed to the contact arm. Generally, the insulator is attached with an adhesive to the contact arm. However, this requires an extra step in the assembly of the circuit breaker, thus increasing the cost.
An arc chute is disposed adjacent the separable main contacts for dispersing the arc resulting from contact separation. One arc chute is provided for each pole and is generally captured in the compartment between opposing sidewalls. In some known applications, the sidewalls are formed with barriers for locating the arc chute to prevent the arc from moving along the longitudinal axis of the circuit breaker. However, molding of these barriers may interfere with placement of the line conductor in the base.
Some circuit breakers are provided with slot motors. The slot motors assist the separable main contacts in blowing open. Known slot motors consist either of a series of generally U-shaped steel laminations encased in electrical insulation or of a generally U-shaped, electrically insulated solid bar which may be disposed adjacent the separable main contacts. Slot motors concentrate the magnetic field generated during a relatively high level overcurrent condition to increase the magnetic repulsion forces and assist the contact arms in blowing open. Such slot motors can be relatively expensive.
It is an object of the present invention to provide a cradle with heat-treated latch and reset surfaces which overcomes the problems associated with the prior art.
It is a further object of the present invention to provide a cradle with heat-treated latch and reset surfaces that is not brittle or distorted.
It is another object of the present invention to provide a support for bracing the sidewalls of the molded case against forces resulting from relatively high overcurrent conditions, such as a short circuit condition.
It is a further object of the present invention to provide a barrier adjacent the area of contact separation of the main contacts to prevent the arc products from attacking various components of the circuit breaker.
It is a further object of the present invention to provide means for capturing the arc chutes to prevent their movement along the longitudinal axis of the circuit breaker.
It is yet a further object of the present invention to provide means for holding an insulation barrier in place on the lower contact arm without the use of adhesives.
It is another object of the present invention to provide a slot motor which resolves the problems associated with known slot motors.
It is a further object of the present invention to provide a slot motor, relatively less expensive than known slot motors.
It is yet a further object to provide means for accomplishing multiple design objectives.
Briefly, the present invention relates to a two piece cradle assembly having a cradle portion and a heat-treated portion. The heat-treated portion forms latch and reset surfaces. The cradle portion is integrally formed from a pair of spaced apart cradle-shaped arms joined together by a connecting portion. The heat treated portion is securely fastened to the connecting portion to form the two piece cradle assembly. Key blocks or elongated molded blocks are used to support the sidewalls. These key blocks are formed with a key shaped projection along one side, adapted to be received in key shaped grooves molded in the sidewalls of a circuit breaker base. The key shaped projections and the key shaped grooves may be formed as a dovetail connection. These key blocks may be secured to either a line conductor or the base and extend substantially to the tops of the sidewalls. The key blocks provide additional support for the sidewalls from forces resulting from relatively high overcurrent conditions, such as a short circuit condition. In addition to supporting the sidewalls, the key blocks form a barrier between the area of contact separation of the main contacts and other components to reduce the amount of arc products allowed to interact with other components in the circuit breaker. The key blocks also form a stop surface for capturing the arc chutes to prevent movement of the arc chutes along the longitudinal axis of the circuit breaker. Lastly, the key blocks hold the insulation barrier on the line conductor in place, thus obviating the need for adhesives. In an alternate embodiment of the invention, a slot motor is incorporated into the key blocks. More particularly, the key blocks are provided with a longitudinal bore. This bore is adapted to receive a metal screw, used to secure the key blocks to a metal plate molded in the base of the circuit breaker. The metal screws and the metal plate are insulated from the line conductor. The metal screws as well as the embedded metal plate form the slot motor. Counterbores may be provided in the key blocks for providing additional metallic material if necessary.
US Referenced Citations (5)
| Number |
Name |
Date |
Kind |
|
4489295 |
Altenhoff et al. |
Dec 1984 |
|
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4554423 |
Flick et al. |
Nov 1985 |
|
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4638277 |
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Continuation in Parts (1)
|
Number |
Date |
Country |
| Parent |
256878 |
Oct 1988 |
|
Patent Grant
5027096
