FORM 2
THE PATENTS ACT, 1970
COMPLETE SPECIFICATION
(See Section 10)
HINGE COVER IN MOULDED CASE CIRCUIT BREAKER
numbered as dated
INVENTORS:
1. MOHAN. K. MURUKATE
2. SANDEEP SINGH. H. RAWAT
APPLICANT:
LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No. 278,
Mumbai, 400 001, Maharashtra
INDIA.
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THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
NATURE OF THE INVENTION

HINGE COVER IN MOULDED CASE CIRCUIT BREAKER
A) TECHNICAL FIELD
[0001] The present invention generally relates to a switching device like circuit breaker and more particularly to a cover in a circuit breaker such as moulded case circuit breaker.
B) BACKGROUND OF THE INVENTION
[0002] The Electrical switching devices are used to protect the electrical circuitry and equipment from the damage due to an abnormal condition, such as an overload condition, a relatively high level short circuit or a fault condition.
[0003] A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. The Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city. There are multiple types of circuit breakers currently available in the market. For example, the different types of circuit breakers available in the market are
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the magnetic circuit breaker, the thermal breaker, the thermo magnetic circuit breaker etc.
[0004] The Magnetic circuit breakers are provided with a solenoid (electromagnet) in which the pulling force is increased proportionately with the magnitude of current. The contacts in the circuit breaker are held closed by a latch. When the current passed through the solenoid increases beyond the preset rating of the circuit breaker, the latch is released by the pulling force of the solenoid to permit the contacts to be opened by a spring action. Some types of magnetic breakers have a hydraulic time delay feature to allow brief surge current beyond a preset level for starting motor or energizing electrical equipment.
[0005] The Thermal breakers use a bimetallic strip, which is heated and bent with increased current, and is similarly arranged to release the latch. Such thermal breakers are commonly used with motor control circuits. Thermal breakers often have a compensation element to reduce the effect of ambient temperature on the device rating.
[0006] The Thermo magnetic circuit breakers are found mostly in distribution boards. The thermo magnetic circuit breakers include both an electromagnet that responds instantaneously to large surges in current (short circuits) and the bimetallic strip which responds with respect to less extreme but long -term over current conditions.
[0007] There are different technologies used in circuit breakers and they do not always fall into distinct categories. The commonly used circuit breakers in domestic, commercial and light industrial applications at low voltages (less than 1000 V)
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include a miniature circuit breaker (MCB) and a moulded case circuit breaker (MCCB).
[0008] A miniature circuit breaker (MCB) is used for a rated current of not more than 100 A. the trip characteristics are not adjustable normally. The MCB employs thermal or thermo-magnetic principles. The MCCB (Moulded Case Circuit Breaker) is used for a rated current up to 1600 A. The MCCB uses the Thermal or thermal-magnetic operation. The trip current may be adjusted in MCCB.
[0009] The Circuit breakers for larger currents are usually arranged with pilot devices to sense a fault current and to operate the trip opening mechanism.
[0010] The switching devices are usually installed in an enclosure so that the entire control and distribution network arranged in the form of metallic sheets and/or cable wires are housed inside the enclosure. All the operating means are arranged outside the enclosure to prevent an access to the high voltage sections to eliminate the generation of a potential hazard. It is often desirable or essential that the settings of the switching devices remain undisturbed in the switching device during a maintenance operation. An unauthorized or inadvertent changing of the position of these breakers could result in unwanted interruptions to service or operations and serious damage to an electrical apparatus, or even serious harm to a person. For example, the accidental actuation of a circuit breaker might result in electrocution or shock to a workman performing electrical work or repair on equipment downstream from the circuit breaker.
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[0011] Therefore enough safety measures must be taken to prevent another person from inadvertently returning the circuit breaker handle to the ON position, when a worker is doing electrical work in an area other than the immediate vicinity of the circuit breaker box or electrical panel. One such safety measure is the addition of a locking assembly to the switching device to prevent the displacement of the circuit breaker operating handle.
[0012] The circuit breaker may be reset, either manually or automatically, to resume normal operation. Many of these circuit breakers include a switch knob movable between an 'On' and an 'Off position, hereinafter mentioned as a 'knob up' and a 'knob down' position. A rampart surrounds the switch knob between the 'knob up' and the 'knob down' positions define a switch knob cavity.
[0013] There are various types of casings and locking structures currently available in the market for the circuit breaker or the switchgear to lock-out the switch knob for security purpose. The locking device or the cover structure is used in the circuit breakers to avoid any external hindrance to the operation of the circuit breaker and to enable the proper functioning of the system. The related casings and the locking structures that are currently available in the market are disclosed in the following prior art patents and published patent applications.
[0014] The US Patent number 5801331 issued to Jurgen Zachrai discloses a switch gear cabinet with a door and cover hingedly connected to topside of the bottom
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housing. The front side of the cover has holding flaps that are hooked and held by a bent border of the switch gear cabinet door.
[0015] The US Patent number 5593020 issued to Richard L Alexander discloses a safety device for locking a circuit breaker. The safety device has a base member hingedly coupled to a cover assembly. The cover has plurality of protrusions that are received in the respective grooves of the base member. A plurality of locking pins provided with plurality of spaced apart and longitudinally extended elongated slots that are selectively received in the grooves of the base member to receive the protrusions in the cover.
[0016] The US Patent number 4979634 issued to Paul V. Begley discloses a hold-open hinge mechanism for a moulded plastic rain proof cover for a circuit breaker. The hinge mechanism includes an integrally moulded pivot pin and a hinge member provided respectively on the cover member and the cover base so that the cover base pivotally engages the pivot pin. When the cover is opened at a given angle, the projections on the cover engage the surface mounted with the cover to releasably maintain the cover in open position.
[0017] The US patent number 4105136 issued to William E May discloses a snap-in molded cover assembly for a switch gear. The switch gear has an access opening that is closed by an integral frame provided with a hinged cover so that the hinged cover is closed to close the access opening.
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[0018] Thus none of the above mentioned cover structure is assembled and anchored firmly and simply. Also none of the currently available cover assembly for a circuit breaker is able to withstand the thermodynamic forces generated during the abnormal condition of fault condition. Also there is yet another need to provide nuff strength to cover assembly during the short circuit condition to with stand the thermal stresses.
C) OBJECT OF THE PRESENT INVENTION
[0019] The primary object of the present invention is to develop a cover that may be staunchly connected to the housing of moulded case circuit breaker to withstand the thermodynamic forces generated in the circuit breaker during abnormal condition of fault condition.
[0020] Another object of the present invention is to develop a cover assembly that may be assembled easily and quickly.
[0023] Yet another object of the present invention is to develop a cover assembly that is easily secured to the housing of the circuit breaker using minimum hardware components.
[0024] Yet another object of the present invention is to develop a cover assembly with nuff strength to withstand the thermal stresses generated during the short circuit condition.
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D) SUMMARY OF THE INVENTION
[0025] The abovementioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.
[0026] The various embodiments of the present invention provide a hinged cover assembly for moulded case circuit breaker and a moulded case circuit breaker. According to one embodiment of the present invention, a cover is hingedly connected to the top of a housing provided to accommodate plurality of circuit breaker units. The breaker units are mounted on a panel attached to the base of the housing. The breaker units are mounted side by side to provide more free space. The cover is connected to the top side of the housing so that the cover is kept opened at preset angle to provide unlimited access to the breaker units. The cover is connected to the housing through a hinge so that the assembly time is reduced greatly. The arc chute plates are moved out to enable the cooling and the extinguishing of the arc generated during the short circuit condition.
[0027] The hinge is provided to anchor the cover with the housing so that the cover may withstand the thermal stresses developed during the rectification of the abnormal operating conditions such as short circuit condition. The hinge is designed in such a way that the gases produced in arcing chamber during the short-circuit condition press the hinge against the housing to withstand the stresses developed during short circuit conditions. The cover is hinged to the housing thereby eliminating the need for two
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cover fixing hardware to reduce the assembly time of the breaker and to provide more space for movement.
[0028] According to another embodiment of the present invention, a moulded circuit breaker assembly is provided with a hinged cover to with stand the thermodynamic forces generated in the circuit breaker housing during the short circuit condition. The circuit breaker assembly is provided with a DIN - rail compatibility and a compact structure. When the breaker is mounted on a base plate, the mounting hardware presses the cover against the housing so that cover can withstand the stresses developed during abnormal operating conditions. On the other hand, when the breaker is mounted on DIN-rail, the hinge holds the cover with housing firmly so that breaker could withstand stresses developed during abnormal operating conditions.
[0029] The embodiments of the present invention provide a cover assembly in which the cover is staunchly anchored to the housing to withstand the thermodynamic forces generated during the short circuit condition or abnormal condition. The cover is hinged to the housing and provided with adequate strength to withstand the stresses developed in the breaker during abnormal /fault conditions. The cover assembly is provided with sufficient nuff strength during short circuit condition to withstand thermal stresses.
[0030] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.
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E) BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:
[0032] FIGURE. 1 illustrates a perspective view of a moulded case circuit breaker assembly with cover kept in closed condition according to one embodiment of the present invention.
[0033] FIGURE.2 illustrates a perspective view of a moulded case circuit breaker assembly with cover kept in open condition according to one embodiment of the present invention.
[0034] Although specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.
F) DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0035] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments which may
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be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.
[0036] The embodiments of the present invention provide a moulded case circuit breaker with a hinged cover and a hinged cover assembly for moulded case circuit breaker. According to one embodiment of the present invention, a cover is hingedly connected to the top of a housing that is provided to accommodate plurality of circuit breaker units. The circuit breaker units are mounted on a panel attached to the base of the housing. In another embodiment of the present invention, the circuit breaker units are mounted on a DEM rail provided at the base plate of the housing. The breaker units are mounted side by side to provide more free space at the upper portion of the housing thereby providing the movement space for the deionising plates provided to cool and extinguish the arcs generated between contacts in the circuit breaker unit.
[0037] The cover is connected to the top side of the housing so that the cover is kept opened at preset angle to provide unlimited access to the breaker units. The cover is connected to the housing through a hinge so that the assembly time is reduced greatly. The arc chute plates are moved out to enable the cooling and the extinguishing of the arc generated during the short circuit condition.
[0038] The hinge is provided to anchor the cover with the housing so that the cover may withstand the thermal stresses developed during the rectification of the abnormal
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operating conditions such as short circuit condition. The hinge is designed in such a way that the gases produced in arcing chamber during the short-circuit condition press the hinge against the housing to withstand the stresses developed during short circuit conditions. The cover is hinged to the housing thereby eliminating the need for two cover fixing hardware to reduce the assembly time of the breaker and to provide more space for movement.
[0039] The breaker assembly is provided with a DIN - rail compatibility and a compact structure. When the breaker is mounted on a base plate, the mounting hardware presses the cover against the housing so that cover can withstand the stresses developed during abnormal operating conditions. On the other hand, when the breaker is mounted on DIN-rail, the hinge holds the cover with housing firmly so that breaker could withstand stresses developed during abnormal operating conditions.
[0040] According to another embodiment of the present invention, a moulded case circuit breaker is provided with a hinged cover to with stand the thermo dynamic forces generated in the circuit breaker housing during the generation of abnormal condition and short circuit condition.
[0041] The embodiments of the present invention provide a cover assembly in which the cover is staunchly anchored to the housing to withstand the thermodynamic forces generated during the short circuit condition or abnormal condition. The cover is hinged to the cover and provided with adequate strength to withstand the stresses
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developed in the breaker during abnormal /fault conditions. The cover assembly is provided with sufficient nuff strength during short circuit condition to withstand thermal stresses.
[0042] The FIG. 1 shows a side perspective view of a moulded case circuit breaker assembly with cover kept in half closed condition according to one embodiment of the present invention. With respect to FIG. 1, a cover plate is connected to a housing that accommodates a circuit breaker unit through a hinge mechanism. The cover is hingedly connected to top side of the housing so that the number of hardware components used to fasten the cover with the housing is reduced thereby reducing the assembly time. The cover has a slot through which the knob of the circuit breaker unit is inserted.
[0043] The FIG.2 shows a side perspective view of the moulded case circuit breaker assembly with the cover kept in open condition. With respect to FIG. 2, the circuit breaker assembly has a housing in which plurality of circuit breaker units are mounted on a DIN rail provided on the base of the housing. The cover is hingedly connected to the top side of the housing so that the cover is kept open at preset angle to provide unlimited access to the breaker units to carry out the maintenance and installation operations of the circuit breaker units freely. The knob provided in the circuit breaker to reset the breaker is inserted into the slot provided in the cover plate.
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G) ADVANTAGES OF THE INVENTION
[0044] Thus the various embodiments of the present invention provides a hinged cover for moulded case circuit breaker to withstand the thermodynamic forces generated during the short circuit condition or the abnormal condition. Since the cover is hinged to the top side of the housing, the need for the plurality of hardware components is eliminated thereby reducing the assembly time of the circuit breaker device. The cover assembly is provided with sufficient nuff strength to with stand the thermal stresses generated during the short circuit condition or abnormal condition.
[0045] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.
[0046] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the present invention described herein and all the
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statements of the scope of the invention which as a matter of language might be said to fall there between.
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CLAIMS
WHAT IS CLAIMED IS:
1. A moulded case circuit breaker comprising:
A housing;
Circuit breaker components are assembled in said housing; and
A cover assembly;
Wherein the cover plate is hinged to housing at one point.
2. The circuit breaker according to claim 1, wherein the cover plate is hinged to the top side of the housing.
3. The circuit breaker according to claim 1, wherein the cover plate is hinged to withstand the stresses generated during the abnormal condition.
4. The circuit breaker according to claim 1, wherein the cover is hinged to withstand the thermal stresses generated during the abnormal condition.
5. The circuit breaker according to claim 1, wherein the cover is hinged to withstand the thermal stresses generated during the short circuit condition.
6. The circuit breaker according to claim 1, wherein the cover is hinged at the top side to provide additional space in the housing.
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7. The circuit breaker according to claim 1, wherein the cover is hinged at the top side to provide additional space to enable the arcing plates to move upwardly to cool and extinguish the arc generated during the short circuit condition.
8. The circuit breaker according to claim 1, wherein the cover is hinged to provide nuff strength to the cover to with stand the thermal stress generated during the short circuit condition.
9. The circuit breaker according to claim 1, further comprises a DIN rail mounted on the base of the hosing the circuit breaker to hold the circuit breaker units.
10. A hinged cover assembly for the moulded case circuit breaker.
Dated this the 28th day of February, 2008
Rakesh Prabhu,
Patent Agent, ALMT Legal,
No.2, Lavelle Road, Bangalore-560 001, INDIA
The Controller of Patents, The Patent office, At Mumbai
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ABSTRACT
The various embodiments of the present invention provide a moulded case circuit breaker assembly with a hinged cover and a hinged cover. The cover is hinged to the top side of the housing provided to accommodate the circuit breaker units to withstand the thermodynamic forces generated during the short circuit condition. The cover is hinged at to eliminate the need for the two hardware components used in the currently available devices thereby reducing the assembly time. The cover is hinged at the top side to provide sufficient space for the movement of the arcing plates during the short circuit condition.
10 Claims, 2 Drawing Sheets.
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