FORM 2
THE PATENTS ACT, 1970
COMPLETE SPECIFICATION
(See Section 10)
ARC RUNNER FOR ELECTRICAL SWITCHING APPARATUS
numbered as dated
INVENTORS:
1. PRAVIN P. MHASKAR
APPLICANT:
LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No 278,
Mumbai, 400 001, Maharashtra,
INDIA


ARC RUNNER FOR ELECTRICAL SWITCHING APPARATUS
A) TECHNICAL FIELD
[0001] The present invention generally relates to an electrical switching device such as circuit interrupters, electrical isolation device, switch gears, circuit breaker, etc., and particularly to an arc extinguishing device or arc isolating device like arc chute or arc plate assembly in the circuit breaker. The present invention is more particularly relates to an arc movement and arc plates in the arc chute assembly of a 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. The Electrical switching devices include, for example, circuit switching devices and circuit interrupters such as circuit breakers, contactors, motor starters, motor controllers and other load controllers
[0003] Generally a circuit breaker device is a mechanical switching device which is capable of making, carrying and breaking currents under normal circuit conditions. The circuit breaker is also capable of making and carrying currents for a specified


time and breaking currents under specified abnormal circuit conditions, such as a short circuit condition. The circuit breaker device can control and protect an electrical circuit and people operating an electrical device. The circuit breaker has contact which are made to contact or separate from each other to supply or to cut off electrical current supply to a device. An arc drawn between the circuit interrupting contacts is very violent and has very high energy. The extinction of such an arc to interrupt the flow of large fault currents is an extremely challenging task. The arc must be extinguished quickly to prevent damaging consequences to the electrical wiring, a load and also to the circuit interrupting device itself. Hence the current breaking capacities must be increased while keeping the size of interrupting device in compact.
[0004] Normally a protective equipment on high-voltage transmission lines prevents the formation of an unwanted arc, or ensures that it is de-energized within tens of milliseconds. The electrical apparatus arranged to interrupt high-voltage circuits is designed to safely direct the resulting arc so that it dissipates without damage. The high voltage circuit breakers often use a blast of high pressure air, a special dielectric gas (such as SF6 under pressure), or immersion in mineral oil to quench the arc when the high voltage circuit is broken.
[0005] The arc extinguishing device or an arc quenching device has an arc chamber in which the arc drawn between the two contacts in a breaker contact system is extinguished or quenched. Hence the design of an arc chamber is very important in this manner. The arc chamber consists of a pair of contacts and an arc chute. The arc chute includes a stack of closely spaced metallic plates called splitter plates and two


side walls. The metallic plates are generally made up of mild steel and have a groove on the contact side to pull an arc inside the arc chute. The mild steel is used for a splitter plate to pull an arc inside the arc chute due to its ferromagnetic properties. The arc pulled inside the arc chute is split by the splitter plates and extinguished. It is very important to cool the arc and to drag it away from contacts, to quench or extinguish an arc effectively. The cooling of arc is done by the splitter plates.
[0006] The splitter plates are generally coated with the material having good arc mobility such as Copper or Nickel. But the main drawback in this type coated splitter plates is that the coating on the splitter plates gets vanished resulting into inferior performance for the next short circuit condition, after clearing the first or maximum a second shot during the short circuit conditions, The erosion of the coating layer on the splitter plates after two short circuit conditions results into the higher energy dissipation and higher thermal and mechanical stresses on the system.
[0007] The Circuit breakers and other electrical switching apparatus such as the circuit switching devices and other circuit interrupters like contactors, motor starters, motor controllers and other load controllers, typically include a set of stationary electrical contacts and a set of moveable electrical contacts. The stationary and moveable contacts are in physical contact with one another when a current is supplied to a load through a circuit breaker. When the electrical supply to the load is to be interrupted, the moveable contacts are displaced away from the stationary contacts and a gap is provided between the movable and the stationary contacts, thereby


preventing the actual physical contact between the movable and the stationary contacts.
[0008] The separation of the moveable contacts away from the stationary contacts results in the formation of an electrical arc in the gap that is formed between the movable and the stationary contacts during the separation period. Such an arc is generally undesirable as the arc provides a pathway for an abnormal current flow to the load through the circuit breaker. As a result the load is subjected to a heavy stress. Additionally, the electrical arc generated between the contacts often results in vaporization or sublimation of the contact material itself, eventually resulting in destruction or pitting of the moveable and stationary contacts. Hence there is a need to eliminate and extinguish the generated arc or to move the arc quickly to reduce the stress induced in system.
[0009] Typically the moveable contact is attached with driveshaft pivotally in such a manner that the movable contact is moved along the drive shaft, when a guide mechanism is actuated by a trip bar. An arc plate assembly is provided adjacent to arc movement path to draw the arc from the gap to quench it. The arc plate assembly removes the heat from the arc by lengthening the arc to quench the generated arc. The Arc plate assembly includes a plurality of spaced apart arc plates that are mounted in a holder.
[0010] Generally the arc plate stack divides the arc voltage in the circuit breaker to extinguish the generated arc and to produce a current-limiting effect during the operation of an air circuit breaker to provide downstream protection. The arc plate


assembly cools the arc and splits the arc into series of arcs of smaller lengths. The arcs are made to contact the plates and cooled by the dissipation of the heat energy to the plates in the arc plate assembly. The cooling of the arc also depends on the flow of the gas passed over the plates and hot gas removed out of a vent in the circuit breaker housing. The geometry of the arc plates, the number of plates within the arc chute and other parameters such as the spacing between arc plates are selected and adjusted to provide optimum arc dissipation. Additionally the arc chute assembly is provided with an arc horn or other structure which is specifically designed to draw the arc into the arc chute.
[0011] An arc horn generally comprises an extension of an arc plate which is bent or otherwise directed towards the direction of movement of arc in the arc plate assembly. The arc horns or such devices are most often arranged on the first arc plate among the arc plate stack in the arc chute. They are designed to draw the arc away from the separable contacts upwardly into the other arc plates. However the arc has a tendency to follow different paths in moving from the separable contacts towards an arc plate assembly. The movement of arc in the arc plate assembly may produce erosion on the arc plates heavily and damage to the nearby separable contacts.
[0012] Hence there is a need to develop an arc runner to provide a quick movement and extinguishing of arcs in an arc plate assembly. Also there is a need to develop a compact arc plate assembly and to reduce the damage to the arc plates in the arc plate assembly during the arc quenching process.


C) OBJECT OF THE INVENTION
[0013] The primary object of the present invention is to develop and provide an arc runner to enable quick movement and extinguishing of arc in an arc plate assembly in a circuit breaker.
[0014] Another object of the present invention is to develop an arc runner which also acts as an additional de-ionizing plate in the arc plate chute assembly to provide an additional breaking of the arc in the arc chute assembly to increase the efficiency of the arc quenching process.
[0015] Yet another object of the present invention is to develop and provide an arc runner which is formed integrally with the circuit breaker to reduce the size of the circuit breaker assembly.
[0016] Yet another object of the present invention is to develop and provide an arc runner to reduce the breaking voltage of the arc to improve the efficiency the arc quenching process.
[0017] 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.


D) SUMMARY OF THE INVENTION
[0018] The abovementioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.
[0019] The various embodiments of the present invention provide a system for extinguishing an arc in a circuit breaker and an electrical switching device with an arc runner. According to one embodiment of the present invention, an arc extinguishing system for a circuit breaker has an arc runner formed integrally with a stationary contact of an electrical switching device to direct an arc towards an arc chute containing a number of deion plates or splitter plates. The arc runner is formed protrudingly from the stationary contact of the switching device and is extended till the first or the lower most plate of the arc chute. The arc runner acts as a lowermost plate of the arc chute so that the arc runner not only directs the arc towards the arc chute but also acts as a deion plate to break the arc so that the arc is extinguished quickly and easily.
[0020] According to another embodiment of the present invention, an electrical switching apparatus is provided with an arc plate to direct an arc towards an arc chute to extinguish the arc quickly and easily. The electrical switching device includes a housing, a pair of separable contacts, an arc runner and an arc chute. The pair separable contacts containing a movable contact and a stationary contact are encased within the housing. A projection is formed integrally with the stationary contact and


protruded from the stationary contact towards the first or the lowermost plate of the arc chute to direct the arc generated between the two contacts towards the arc chute. The arc chute has plurality of plates called splitter plates or deion plates arranged parallely between a pair of side walls. The plates are inclined to the vertical plane at a preset angle. The arc chute is installed very near to the separable contacts to attract an arc generated between the separable contacts and to extinguish the arc quickly, easily and efficiently.
[0021] The pair of contacts are closed to supply an electrical power from a power source to a load. The contacts are moved away from each other during the abnormal flow of current to prevent the supply of abnormal current to the load and to prevent the damage to the load.
[0022] The arc runner is an integral protrusion from the fixed or stationary contact member. The protrusion is not an attached component and it is formed as part and parcel of fixed contact or formed integrally with the stationary contact. The integral protrusion is extended till first arc plate of arc plate structure so that the arc plate not only acts as an arc runner but also acts as a deion plate to break and extinguish an arc.
[0023] The arc chute contains multiple number plates called splitter plates or deion plates arranged parallely between two side plates. The splitter plates are inclined at a preset angle with respect to the side wall plates or vertical plane. The size, geometry and the inclination of the splitter plates depends on the parameters or factors such as


architecture of contact system, mechanism speed, path traversed by moving contact during opening, size of the contact gap and dielectric strength of the plates etc.
[0024] Thus the arc runner helps and plays an important role in the movement of arc from the contact to stack of deion plates. The arc runner acts as an emulated deion plate. The arc runner not only acts as an arc horn in moving the arc towards the deion plates or splitter plates in the arc chute but also acts as a part of the deion plate stack thereby proving one additional breaking of the arc. Thus the arc runner helps in reducing the voltage per break to extinguish the arc quickly to clear an electrical fault efficiently and effectively. The arc runner is formed integrally with the stationary contact to reduce the size of the circuit breaker and to obtain a compact circuit breaker easily.
[0025] 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.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0026] 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:
[0027] FIGURE. 1 illustrates a side sectional view of an electrical switching device provided with an arc runner according to one embodiment of the present invention.


[0028] FIGURE. 2 illustrates a side sectional view of an arc chute assembly in an electrical switching device provided with an arc runner according to one embodiment of the present invention.
[0029] FIGURE. 3 illustrates a side sectional view of an arc chute assembly in an electrical switching device provided with an arc runner according to one embodiment of the present invention.
[0030] 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
[0031] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may 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.


[0032] The various embodiments of the present invention provide a system for extinguishing an arc in a circuit breaker and an electrical switching device with an arc runner. According to one embodiment of the present invention, an arc extinguishing system for a circuit breaker has an arc runner formed integrally with a stationary contact of an electrical switching device to direct an arc towards an arc chute containing a number of deion plates or splitter plates. The arc runner is formed protrudingly from the stationary contact of the switching device and is extended till the first or the lower most plate of the arc chute. The arc runner acts as a lowermost plate of the arc chute so that the arc runner not only directs the arc towards the arc chute but also acts as a deion plate to break the arc so that the arc is extinguished quickly and easily.
[0033] According to another embodiment of the present invention, an electrical switching apparatus is provided with an arc plate to direct an arc towards an arc chute to extinguish the arc quickly and easily. The electrical switching device includes a housing, a pair of separable contacts, an arc runner and an arc chute. The pair separable contacts containing a movable contact and a stationary contact are encased within the housing. A projection is formed integrally with the stationary contact and protruded from the stationary contact towards the first or the lowermost plate of the arc chute to direct the arc generated between the two contacts towards the arc chute. The arc chute has plurality of plates called splitter plates or deion plates arranged parallely between a pair of side walls. The plates are inclined to the vertical plane at a preset angle. The arc chute is arranged near the separable contacts to attract an arc


generated between the separable contacts and to extinguish the arc quickly, easily and efficiently.
[0034] The pair of contacts are closed to supply an electrical power from a power source to a load. The contacts are moved away from each other during the abnormal flow of current to prevent the supply of abnormal current to the load and to prevent the damage to the load.
[0035] The arc runner is an integral protrusion from the fixed or stationary contact member. The protrusion is not an attached component and it is formed as part and parcel of fixed contact or formed integrally with the stationary contact. The integral protrusion is extended till first arc plate of arc plate structure so that the arc plate not only acts as an arc runner but also acts as a deion plate to break and extinguish an arc. In one embodiment of the present invention the arc runner is formed in a button shape.
[0036] The arc chute contains multiple number plates called splitter plates or deion plates arranged parallely between two side plates. The splitter plates are inclined at a preset angle with respect to the side wall plates or vertical plane. The size, geometry and the inclination of the splitter plates depends on the parameters or factors such as architecture of contact system, mechanism speed, path traversed by moving contact during opening, size of the contact gap and dielectric strength of the plates etc.


[0037] Thus the arc runner helps and plays an important role in the movement of arc from the contact to stack of deion plates. The arc runner acts as an emulated deion plate. The arc runner not only acts as an arc horn in moving the arc towards the deion plates or splitter plates in the arc chute but also acts as a part of the deion plate stack thereby proving one additional breaking of the arc. Thus the arc runner helps in reducing the voltage per break to extinguish the arc quickly to clear an electrical fault efficiently and effectively. The arc runner is formed integrally with the stationary contact to reduce the size of the circuit breaker and to obtain a compact circuit breaker easily.
[0038] The FIG.l shows a side sectional view of an electrical switching device provided with an arc runner according to one embodiment of the present invention. With respect to FIG. 1, an electrical switching apparatus is provided with an arc plate to direct an arc towards an arc chute to extinguish the arc quickly and easily. The electrical switching device includes a housing 10, a pair of separable contacts 22, an arc runner and an arc chute. The pair separable contacts containing a movable contact 24 and a stationary contact are encased within the housing 10. A projection is formed integrally with the stationary contact and protruded from the stationary contact towards the first or the lowermost plate of the arc chute to direct the arc generated between the two contacts towards the arc chute. The arc chute has plurality of plates called splitter plates or deion plates arranged parallely between a pair of side walls. The plates are inclined to the vertical plane at a preset angle. The arc chute is arranged near the separable contacts to attract an arc generated between the separable contacts and to extinguish the arc quickly, easily and efficiently.


[0039] The pair of contacts are closed to supply an electrical power from a power source to a load. The contacts are moved away from each other during the abnormal flow of current to prevent the supply of abnormal current to the load and to prevent the damage to the load. The contacts are closed or separated by operating a handle 12. The entire circuit breaker housing is closed with a circuit breaker cover 11. The movable contact 24 is moved along the drive shaft 21, when a guide mechanism is actuated by a trip bar 23.
[0040] The arc runner is an integral protrusion from the fixed or stationary contact member. The protrusion is not an attached component and it is formed as part and parcel of fixed contact or formed integrally with the stationary contact. The integral protrusion is extended till first arc plate of arc plate structure so that the arc plate not only acts as an arc runner but also acts as a deion plate to break and extinguish an arc. In one embodiment of the present invention the arc runner is formed in a button shape.
[0041] The arc chute contains multiple number plates called splitter plates or deion plates arranged parallely between two side plates. The splitter plates are inclined at a preset angle with respect to the side wall plates or vertical plane. The size, geometry and the inclination of the splitter plates depends on the parameters or factors such as architecture of contact system 22, mechanism speed, path traversed by moving contact 24 during opening, size of the contact gap and dielectric strength of the plates etc.


[0042] The FIG. 2 shows a side sectional view of an arc chute assembly in an electrical switching device provided with an arc runner 35 according to one embodiment of the present invention. With respect to FIG.2, an arc chute 33 is arranged very near to a stationary contact 31 of a circuit breaker. An arc runner 35 is formed integrally with the stationary contact 31 to protrude towards the arc chute 33 to direct an arc generated between the two contacts towards the arc chute 33. The arc chute 33 has plurality of plates called splitter plates or deion plates arranged parallely between a pair of side walls. The plates are inclined to the vertical plane at a preset angle. The arc chute 33 is arranged near the separable contacts to attract an arc generated between the separable contacts and to extinguish the arc quickly, easily and efficiently.
[0043] The arc runner 35 is an integral protrusion from the fixed or stationary contact member. The protrusion is not an attached component and it is formed as part and parcel of fixed contact or formed integrally with the stationary contact 31. The integral protrusion is extended till first arc plate of arc plate structure 33 so that the arc plate not only acts as an arc runner 35 but also acts as a deion plate to break and extinguish an arc. In one embodiment of the present invention the arc runner is formed in a button 34 shape.
[0044] The arc chute contains multiple number plates called splitter plates or deion plates arranged parallely between two side plates. The splitter plates are inclined at a preset angle with respect to the side wall plates or vertical plane. The size, geometry and the inclination of the splitter plates depends on the parameters or factors such as

architecture of contact system, mechanism speed, path traversed by moving contact during opening, size of the contact gap and dielectric strength of the plates etc.
[0045] FIGURE.3 illustrates a side sectional view of an arc chute assembly in an electrical switching device provided with an arc runner according to one embodiment of the present invention.
[0046] Thus the various embodiments of the present invention provide a system for extinguishing an arc in a circuit breaker and an electrical swiching device with an arc runner. An arc runner is provided integrally with the stationary contact of the circuit breaker to direct the arc generated between the contacts towards the arc chute and to act as an additional deion plate to break the arc so that the generated arc is extinguished easily, efficiently and effectively.
[0047] Thus the arc runner helps and plays an important role in the movement of arc from the contact to stack of deion plates. The arc runner acts as an emulated deion plate. The arc runner not only acts as an arc horn in moving the arc towards the deion plates or splitter plates in the arc chute but also acts as a part of the deion plate stack thereby proving one additional breaking of the arc. Thus the arc runner helps in reducing the voltage per break to extinguish the arc quickly to clear an electrical fault efficiently and effectively. The arc runner is formed integrally with the stationary contact to reduce the size of the circuit breaker and to obtain a compact circuit breaker easily.


G) ADVANTAGES OF THE INVENTION
[0048] Thus the various embodiments of the present invention provide a system for extinguishing an arc in a circuit breaker and an electrical switching device. An arc runner is provided integrally with the stationary contact of the circuit breaker to direct the arc generated between the contacts towards the arc chute and to act as an additional deion plate to break the arc so that the generated arc is extinguished easily, efficiently and effectively.
[0049] Thus the arc runner helps and plays an important role in the movement of arc from the contact to stack of deion plates. The arc runner acts as an emulated deion plate. The arc runner not only acts as an arc horn in moving the arc towards the deion plates or splitter plates in the arc chute but also acts as a part of the deion plate stack thereby proving one additional breaking of the arc. Thus the arc runner helps in reducing the voltage per break to extinguish the arc quickly to clear an electrical fault efficiently and effectively. The arc runner is formed integrally with the stationary contact to reduce the size of the circuit breaker and to obtain a compact circuit breaker easily.
[0050] Although the invention is described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims.


[0049] 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 statements of the scope of the invention which as a matter of language might be said to fall there between.


CLAIMS
WHAT IS CLAIMED IS:
1. An electrical circuit switching device comprising:
A housing;
A pair of contacts arranged within the housing;
An arc chute arranged near the contacts; and
An arc runner is formed integrally at one of the contacts to direct an arc
towards the arc chute.
2. The device according to claim 1, wherein the pair of contacts includes a stationary contact and a movable contact.
3. The device according to claim 2, wherein the stationary contacts and the movable contacts are moved towards each other to establish a physical contact between the movable and the stationary contacts to supply an electrical power to a load.
4. The device according to claim 2, wherein the movable contact and the stationary contact are moved away from each other to break a physical contact between the movable contact and the stationary contact to prevent an abnormal electrical power to the load.


5. The device according to claim 1, wherein the arc runner is formed integrally at the stationary contact.
6. The device according to claim 1, wherein the arc runner is formed integrally to protrude towards the arc chute to direct the arc formed in the gap between the stationary contact and the movable contact, towards the arc chute for extinguishing.
7. The device according to claim 1, wherein the arc runner acts as a part of the arc chute to provide an additional breaking of the arc to quench the arc.
8. an arc runner structure for an electrical switching device including a pair of contacts and an arc chute, the structure comprising:
a projection formed integrally at one of the contacts to direct an arc towards the arc chute for quenching.
9. The structure according to claim 8, wherein the projection is formed integrally at the stationary contact.
10. The structure according to claim 8, wherein the projection is protrude from the stationary contact towards the arc chute to direct the arc formed in the gap between the pair of contacts, towards the arc chute for extinguishing.


11. The structure according to claim 8, wherein the arc runner acts as a part of the arc chute to provide an additional breaking of the arc to quench the arc.

ABSTRACT
The various embodiments of the present invention provide a system for extinguishing an arc in a circuit breaker and an electrical switching device with an arc runner. According to one embodiment of the present invention, an arc runner is formed integrally at a stationary contact and protruded towards the first or the lowermost deion plate in an arc chute to direct an arc formed in the gap between a pair of contacts towards the arc chute. The arc runner not only directs the arc towards the arc chute but also acts as an additional deion plate to break and quench the arc.
11 Claims, 3 Drawing Sheets.