Title of Invention	AN ENHANCED SWITCHING DEVICE ADAPTED FOR ARC SHEARING AND QUENCHING
Abstract	The present invention relates to an enhanced switching device having improved performance and switching potentiality. The device comprises housing (1,3), plurality of electrical contacts comprising moving contact system (6). Moving contact system (6) is spring assisted operatively connected to a movable bridge means (5) being slidable so as to accommodate fluid adapted to provide insulation in the device and comprises plurality of ergonomical projections (7) to obviate any possibility of striking or stagnation of the arc. Invention also relates to a method of achieving improved quenching of the arc where ionized fluid is replaced with an unionized fluid and path of arc striking the terminals is blocked.

Title of Invention

AN ENHANCED SWITCHING DEVICE ADAPTED FOR ARC SHEARING AND QUENCHING

Abstract

The present invention relates to an enhanced switching device having improved performance and switching potentiality. The device comprises housing (1,3), plurality of electrical contacts comprising moving contact system (6). Moving contact system (6) is spring assisted operatively connected to a movable bridge means (5) being slidable so as to accommodate fluid adapted to provide insulation in the device and comprises plurality of ergonomical projections (7) to obviate any possibility of striking or stagnation of the arc. Invention also relates to a method of achieving improved quenching of the arc where ionized fluid is replaced with an unionized fluid and path of arc striking the terminals is blocked.

Full Text	FORM2 THE PATENTS ACT, 1970 (39 of 1970) & The Patents Rules, 2003 COMPLETE SPECIFICATION (See section 10; rule 13) Title of the invention - AN ENHANCED ELECTRICAL SWITCHING DEVICE WITH INSULATION SHEATH FOR ARC SHEARING AND A METHOD OF ACHIEVING SUPERIOR ARC QUENCHING THEREOF 2. Applicant (a) NAME : LARSEN & TOUBRO LIMITED (b) NATIONALITY : An Indian Company (c) ADDRESS : L&T House, Ballard Estate, Mumbai 400 001, State of Maharashtra, India 3. PREAMBLE TO THE DESCRIPTION The following specification particularly describes the invention and the manner in which it is to be performed: FIELD OF INVENTION The present invention relates to an enhanced switching device adapted for arc shearing and quenching. More particularly, the invention relates to an enhanced switching device comprising an insulation means with a single solution to ameliorate switching potentiality of the switching device by reducing arcing time and its severity in a multi-break switch. The invention also relates to a method of achieving improved quenching of the arc generated between fixed and moving contacts, and also between two fixed contacts during breaking operation. BACKGROUND AND PRIOR ART When a quad-break electrical switch opens to break the circuit, an arc appears between the fixed and moving contacts. There is also a possibility of arc striking between the two sets fixed contacts, especially when the switch is operated at higher voltages. The performance of the switch can be ameliorated if the time for which these two arcs persist and/or the intensity of the arcs is reduced. The present invention is an effort towards mitigating both the arcs with a single solution. A switching device with an arc shearing plate is already known in the art, as disclosed in the following U.S. patents: US4700030 describes an electric switch in which the arc generated between two mutually mobile contacts inside a 2 chamber is sheared between two insulating walls, one of which belongs to an insulating screen that is quickly inserted between the two contacts, resulting in total insulation between them. US3842228 discloses a circuit breaker in which a wedge member of dielectric material is controlled by a solenoid to thrust between a pair of electrical contacts for opening the contacts and at the same time shearing the arc formed between the contacts. US4752660 is directed to a current limiting circuit breaker with an arc shearing plate which is controlled to move into a position for rapid extinction of an arc formed between contacts being separated upon the occurrence of a predetermined over-current condition. US2005010870 describes an arc-quenching device for circuit breakers having double-break contacts for use in low-voltage distribution systems. A magnetic shield is provided around a prechamber for the purpose of intensifying the magnetic blowing action on an arc formed between the arc guide rails of the prechamber. In addition, a blowing loop is inserted in the arc-quenching circuit and extends in sections parallel to an arc guide rail. Prechamber insulation having a bulge constricting the arc area likewise serves the purpose of optimizing the arc run. However, in all the prior art and existing knowledge as described above, it is imperative to integrate an additional actuating member and/or mechanism for the realization of the effective arc quenching by the use of an insulation barrier. 3 This calls for usage of extra components, leading to increase in the cost and volume of the switching device. Moreover, the shearing plate is operated by separate control means wherein the operation of the plate becomes dependant one, and the attainment of the desired effect becomes a function of various other members in the device. All the existing knowledges pertain to devices with single or dual break contact system and, if adapted to quad break contact system, will require a duplication of the concept of arc shearing plate at two places where the arc is generated. Keeping all this in mind, the present invention is an effort to transcend the prior art to achieve effective arc quenching thereof, in a multi-break switch. The present inventors have found that providing operative integration of means for arc shearing in a predetermined manner a single solution achieving simple, economic and completely reliable way of reducing arcing time and its severity in the plurality of contacts in a multi break switch is achievable thus improving the electrical performance, thereby enhancing the electrical life of the multi-break switch. OBJECTS OF INVENTION Thus the basic object of the present invention is to provide a single solution achieving simple, economic and completely reliable way of enhancing the switching potentiality of the switching device by reducing arcing time and its severity as experienced by the moving as well as fixed contacts in a multi-break switch. 4 Another object of the present invention is to increase the final insulation level by inserting an insulation sheath between the electric contacts of the switch. Yet another object of the present invention is to provide a method of achieving improved quenching of the arc. SUMMARY OF INVENTION Thus according to one aspect of the present invention there is provided an enhanced switching device having improved performance and switching potentiality, said device comprising housing; plurality of electrical contacts received in said housing, said contacts comprising moving contact system wherein said moving contact system being spring assisted operatively connected to a movable bridge means being slidable so as to accommodate fluid adapted to provide insulation in the device; wherein said moving bridge comprises plurality of ergonomical projections having predetermined dimensions located and extended in a manner that the path of the arc travel is blocked thereby obviating any possibility of striking or stagnation of the arc between them after opening operation of the switch. Another aspect of the present invention is to provide a method of achieving improved quenching of the arc, said method comprising : 5 replacement of ionized fluid with an unionized fluid so as to suppress arc; and blocking path of arc striking the terminals in the switching device. DETAILED DESCRIPTION OF INVENTION The said embodiment of the invention will be here forth particularly described with reference to a four-pole switch disconnector with quad break feature. The switching device of the present invention comprises housing assemblies comprising rectangular base housing/casing and top housing/casing, wherein the said base housing/casing is ergonomically designed and provided with pre determined grooves and channels, the major purpose being to house the various current carrying parts and give required support to them, apart from lending a guided path for the moving entity viz. Moving bridge assembly. The said moving assembly capable of moving in the guideway comprises of insulating carriage provided with rectangular grooves, which are adapted to carry contact means. The said carriage/ moving bridge slided in the guideway is adapted to bridge the gaps in the current carrying path between chamfered conducting means mounted on the inside surface of the top housing and terminal means fixed on the base housing. The said guideway is located at the center of the base housing and extends all along the width of the base housing in a manner that the moving bridge, when placed in the said guideway, can be subjected to translatory movement in the lateral direction, parallel to the walls of the base housing. 6 The moving bridge has a feature of an extended projection of an insulating material, along the length of the bridge, which is replicated at all the poles of the bridge and is positioned in such a way that the position of the bridge corresponding to OFF condition of the switch rushes the said extended projection in the gap between the two fixed contacts. The length of the extended projection is kept adequate enough to span the entire width of the fixed contacts, thus completely insulating them from each other. Thus the extended projection of the bridge acts as an insulation sheath in the OFF condition of the switch. The base of the housing comprises pair of current carrying terminals rigidly fixed on the base with the help of screws and mounted in front of each other, perpendicular to the guideway in the base housing and being chamfered on one side in a manner for allowing the smooth entry of the moving contacts onto them. The rectangular top housing/casing is adapted to encompass the whole switch and when placed on the base housing with constituent members therein, forms the contact system of the switch. The said contact spring means, are directly attached to the moving contacts and adapted to keep the moving contacts firmly held in between the fixed terminals and the shorting link, when the switch is in ON condition. The electrical switch has two positions viz. ON and OFF. There is a quick make, quick break mechanism for moving the bridge horizontally between the positions where the moving contacts 7 are sandwiched tightly between the fixed terminals and shorting link, and wherein moving contacts are clear off or isolated from the fixed terminals and shorting link. Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF ACCOMPANYING FIGURES Figure 1 illustrates the front view switching device of the present invention when the switch is in ON condition. Figure 2 illustrates the side view switching device of the present invention when the switch is in ON condition. Figure 3 illustrates the front view of the switching device of the present invention in OFF condition. Figure 4 illustrates the top view of the switching device of the present invention in OFF condition. DETAILED DESCRIPTION OF ACCOMPANYING FIGURES Figure 1 illustrates the front view of the switching device when the switch is in ON condition. The position of the bridge 5 is designated as position B and the moving contacts (6) are 'sandwiched' between the fixed terminals (2) and shorting link (4), thus bridging the gap between them. The top housing (3) is adapted to encompass the whole switch when placed on the base housing (1). 8 In figure 2 the side view of the switching device in ON condition is illustrated. The two sets of moving contacts are shown by hatching and are numbered as 6a and 6b. The continuity is established in the electric circuit and the current flows from first fixed terminal (2a) to first set of moving contacts (6a) to shorting link (4) to second set of moving contacts (6b) and finally to second fixed terminal (2b) . In figure 3 the front view of the switching device in OFF condition is illustrated. The moving bridge (5), which carries the moving contacts (6), is at position A. As a result of which, the fixed terminal (2) and the shorting link (4) in OFF condition get electrically separated. As there is no continuity, there is no current flow in the circuit. In figure 4 the top view of the switching device in OFF condition is illustrated. The base housing (1) comprises guideway (8) adapted for lending a guided path for bridge (5). Refer figure 3. During the transition of the switch from ON to OFF condition, the mechanism flips, the bridge is set in a sudden action and the set of moving contacts (6) adapted to break the electrical circuit is withdrawn from the fixed contacts, an arc is formed between the moving contacts (6) and shorting link (4) and also between the moving contacts (6) and the Terminal (2) . This is accompanied by the formation of a zone of ionized gases, surrounding the place of arcing. The effectiveness of the breaking capacity of the switch depends on the quenching of the arc so formed, which in turn depends on the speedy removal of these ionized gases and replenishing the 9 arcing zone with a block of fresh air, having better insulation properties. As the bridge is suddenly set in motion, the extended projection (7) of the bridge carries out the following two functions. Firstly, the extended projection typically of the length of order of 25-35 mm, moves in a sliding manner towards the arcing zone (Space between 2 and 6 and that between 4 and 6) , thereby replacing the ionized gases in the arcing zone with a block of fresh, unionized air. Since this unionized air has a better insulation property as compared to the ionized air, this results in the rapid quenching of the arc. This action is achieved with the fact that there is no deterioration of any insulating material and a new block of fresh air is pumped in, every time the switch is made to break the circuit. In addition, the extended projection serves a second purpose. Owing to a complete overlap between extended projection (7) and the inner surfaces of terminal (2) and shorting link (4), the extended projection (7) now acts as an arc shearing plate or an insulation sheath, and the arc cannot find a path to strike between the terminal (2) and shorting link (4); hence complete insulation is ensured which obviates any possibility of striking or stagnation of the arc between them after opening operation of the switch, especially when it is commissioned at higher operating voltages. Since these two effects pertaining to a quad-break switch are achieved by making use of a feature of the moving bridge (the bridge being an inevitable in any switching device for 10 carrying contacts), there is no need of addition of any extra component/assembly in the switch, thus making this method the most economical and simple way of achieving efficient arc quenching. Moreover, the desired effect is achieved without any separate control means wherein the aforesaid operation becomes independent of various other members in the device; as the extended projection is an integral feature of the bridge, it essentially comes into action every time the bridge is set in motion (and hence the contacts are broken), giving a complete reliability of operation. The invention has been shown and described in a preferred form only, and by way of example, and many variations may be made in the invention, which will still be comprised within its spirit. It is understood, therefore, that the invention is not limited to the details cited above. There may be a set of fuses, or any other overload safety devices integrated in the said design, which will then act as a switch-disconnector-fuse. Though four-pole design is mentioned, two or three pole design, if required, may easily be designed on the similar lines. Further, it is to be appreciated that the desired effect can also be achieved by varying the profile of the extended projection (7). 11 WE CLAIM 1. An enhanced switching device having improved performance and switching potentiality, said device comprising : housing; plurality of electrical contacts received in said housing, said contacts comprising moving contact system wherein said moving contact system being spring assisted operatively connected to a movable bridge means being slidable so as to accommodate fluid adapted to provide insulation in the device; wherein said moving bridge comprises plurality of ergonomical projections having predetermined dimensions located and extended in a manner that the path of the arc travel is blocked thereby obviating any possibility of striking or stagnation of the arc between them after opening operation of the switch. 2. An enhanced switching device as claimed in claim 1, wherein length of the extended projection is kept adequate so as to span the entire width of fixed contacts thereby completely insulating them from each other. 3. An enhanced switching device as claimed in claims 1 and 2, wherein length of the projection ranges from 25 to 35 mm. 4. An enhanced switching device as claimed in' claims 1, wherein moving bridge being operatively connected to said 12 projections in a manner the sliding motion of moving bridge is adapted to generate sufficient space to accommodate unionized air providing improved insulation. 5. A method of achieving improved quenching of the arc, said method comprising : replacement of ionized fluid with an unionized fluid so as to suppress arc; and blocking path of arc striking the terminals in the switching device. 7. An enhanced switching device as herein substantially described and illustrated with reference to the accompanying figures. Dated this 17th day of October, 2006. Abhishek Sen Of S. Majumdar & Co. Applicant's Agent 13 ABSTRACT TITLE : AN ENHANCED ELECTRICAL SWITCHING DEVICE WITH INSULATION SHEATH FOR ARC SHEARING AND A METHOD OF ACHIEVING SUPERIOR ARC QUENCHING THEREOF The present invention relates to an enhanced switching device having improved performance and switching potentiality. The device comprises housing (1,3), plurality of electrical contacts comprising moving contact system (6). Moving contact system (6) is spring assisted operatively connected to a movable bridge means (5) being slidable so as to accommodate fluid adapted to provide insulation in the device and comprises plurality of ergonomical projections (7) to obviate any possibility of striking or stagnation of the arc. Invention also relates to a method of achieving improved quenching of the arc where ionized fluid is replaced with an unionized fluid and path of arc striking the terminals is blocked. Figure 3 APPLICANT : LARSEN & TOUBRO LIMITED 4 SHEETS SHEET 1 FIGURE 1 Abhishek Sen OfS.MAJUMDAR&CO. (Applicant's Agent) APPLICANT : LARSEN & TOUBRO LIMITED 4 SHEETS SHEET 2 FIGURE 2 Abhishek Sen Of S. MAJUMDAR & CO. (Applicant's Agent) APPLICANT : LARSEN & TOUBRO LIMITED 4 SHEETS SHEET 3 ■R \ } V-TT FIGURE 3 Abhishek Sen Of S. MAJUMDAR & CO. (Applicant's Agent) APPLICANT : LARSEN & TOUBRO LIMITED 4 SHEETS SHEET 4 FIGURE 4 Abhishek Sen OfS.MAJUMDAR&CO. (Applicant's Agent)

Full Text

FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
Title of the invention - AN ENHANCED ELECTRICAL SWITCHING DEVICE WITH
INSULATION SHEATH FOR ARC SHEARING AND A METHOD OF ACHIEVING SUPERIOR ARC QUENCHING THEREOF
2. Applicant
(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian Company
(c) ADDRESS : L&T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF INVENTION
The present invention relates to an enhanced switching device adapted for arc shearing and quenching. More particularly, the invention relates to an enhanced switching device comprising an insulation means with a single solution to ameliorate switching potentiality of the switching device by reducing arcing time and its severity in a multi-break switch.
The invention also relates to a method of achieving improved quenching of the arc generated between fixed and moving contacts, and also between two fixed contacts during breaking operation.
BACKGROUND AND PRIOR ART
When a quad-break electrical switch opens to break the circuit, an arc appears between the fixed and moving contacts. There is also a possibility of arc striking between the two sets fixed contacts, especially when the switch is operated at higher voltages. The performance of the switch can be ameliorated if the time for which these two arcs persist and/or the intensity of the arcs is reduced. The present invention is an effort towards mitigating both the arcs with a single solution.
A switching device with an arc shearing plate is already known in the art, as disclosed in the following U.S. patents:
US4700030 describes an electric switch in which the arc generated between two mutually mobile contacts inside a
2

chamber is sheared between two insulating walls, one of which belongs to an insulating screen that is quickly inserted between the two contacts, resulting in total insulation between them.
US3842228 discloses a circuit breaker in which a wedge member of dielectric material is controlled by a solenoid to thrust between a pair of electrical contacts for opening the contacts and at the same time shearing the arc formed between the contacts.
US4752660 is directed to a current limiting circuit breaker with an arc shearing plate which is controlled to move into a position for rapid extinction of an arc formed between contacts being separated upon the occurrence of a predetermined over-current condition.
US2005010870 describes an arc-quenching device for circuit breakers having double-break contacts for use in low-voltage distribution systems. A magnetic shield is provided around a prechamber for the purpose of intensifying the magnetic blowing action on an arc formed between the arc guide rails of the prechamber. In addition, a blowing loop is inserted in the arc-quenching circuit and extends in sections parallel to an arc guide rail. Prechamber insulation having a bulge constricting the arc area likewise serves the purpose of optimizing the arc run.
However, in all the prior art and existing knowledge as described above, it is imperative to integrate an additional actuating member and/or mechanism for the realization of the effective arc quenching by the use of an insulation barrier.
3

This calls for usage of extra components, leading to increase in the cost and volume of the switching device.
Moreover, the shearing plate is operated by separate control means wherein the operation of the plate becomes dependant one, and the attainment of the desired effect becomes a function of various other members in the device.
All the existing knowledges pertain to devices with single or dual break contact system and, if adapted to quad break contact system, will require a duplication of the concept of arc shearing plate at two places where the arc is generated.
Keeping all this in mind, the present invention is an effort to transcend the prior art to achieve effective arc quenching thereof, in a multi-break switch. The present inventors have found that providing operative integration of means for arc shearing in a predetermined manner a single solution achieving simple, economic and completely reliable way of reducing arcing time and its severity in the plurality of contacts in a multi break switch is achievable thus improving the electrical performance, thereby enhancing the electrical life of the multi-break switch.
OBJECTS OF INVENTION
Thus the basic object of the present invention is to provide a single solution achieving simple, economic and completely reliable way of enhancing the switching potentiality of the switching device by reducing arcing time and its severity as experienced by the moving as well as fixed contacts in a multi-break switch.
4

Another object of the present invention is to increase the final insulation level by inserting an insulation sheath between the electric contacts of the switch.
Yet another object of the present invention is to provide a method of achieving improved quenching of the arc.
SUMMARY OF INVENTION
Thus according to one aspect of the present invention there is provided an enhanced switching device having improved performance and switching potentiality, said device comprising
housing;
plurality of electrical contacts received in said housing, said contacts comprising moving contact system wherein said moving contact system being spring assisted operatively connected to a movable bridge means being slidable so as to accommodate fluid adapted to provide insulation in the device; wherein said moving bridge comprises plurality of ergonomical projections having predetermined dimensions located and extended in a manner that the path of the arc travel is blocked
thereby obviating any possibility of striking or stagnation of the arc between them after opening operation of the switch.
Another aspect of the present invention is to provide a method of achieving improved quenching of the arc, said method comprising :
5

replacement of ionized fluid with an unionized fluid so as to
suppress arc; and
blocking path of arc striking the terminals
in the switching device.
DETAILED DESCRIPTION OF INVENTION
The said embodiment of the invention will be here forth particularly described with reference to a four-pole switch disconnector with quad break feature.
The switching device of the present invention comprises housing assemblies comprising rectangular base housing/casing and top housing/casing, wherein the said base housing/casing is ergonomically designed and provided with pre determined grooves and channels, the major purpose being to house the various current carrying parts and give required support to them, apart from lending a guided path for the moving entity viz. Moving bridge assembly. The said moving assembly capable of moving in the guideway comprises of insulating carriage provided with rectangular grooves, which are adapted to carry contact means. The said carriage/ moving bridge slided in the guideway is adapted to bridge the gaps in the current carrying path between chamfered conducting means mounted on the inside surface of the top housing and terminal means fixed on the base housing. The said guideway is located at the center of the base housing and extends all along the width of the base housing in a manner that the moving bridge, when placed in the said guideway, can be subjected to translatory movement in the lateral direction, parallel to the walls of the base housing.
6

The moving bridge has a feature of an extended projection of an insulating material, along the length of the bridge, which is replicated at all the poles of the bridge and is positioned in such a way that the position of the bridge corresponding to OFF condition of the switch rushes the said extended projection in the gap between the two fixed contacts. The length of the extended projection is kept adequate enough to span the entire width of the fixed contacts, thus completely insulating them from each other. Thus the extended projection of the bridge acts as an insulation sheath in the OFF condition of the switch.
The base of the housing comprises pair of current carrying terminals rigidly fixed on the base with the help of screws and mounted in front of each other, perpendicular to the guideway in the base housing and being chamfered on one side in a manner for allowing the smooth entry of the moving contacts onto them.
The rectangular top housing/casing is adapted to encompass the whole switch and when placed on the base housing with constituent members therein, forms the contact system of the switch.
The said contact spring means, are directly attached to the moving contacts and adapted to keep the moving contacts firmly held in between the fixed terminals and the shorting link, when the switch is in ON condition.
The electrical switch has two positions viz. ON and OFF. There is a quick make, quick break mechanism for moving the bridge horizontally between the positions where the moving contacts
7

are sandwiched tightly between the fixed terminals and shorting link, and wherein moving contacts are clear off or isolated from the fixed terminals and shorting link.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF ACCOMPANYING FIGURES
Figure 1 illustrates the front view switching device of the present invention when the switch is in ON condition.
Figure 2 illustrates the side view switching device of the present invention when the switch is in ON condition.
Figure 3 illustrates the front view of the switching device of the present invention in OFF condition.
Figure 4 illustrates the top view of the switching device of the present invention in OFF condition.
DETAILED DESCRIPTION OF ACCOMPANYING FIGURES
Figure 1 illustrates the front view of the switching device when the switch is in ON condition.
The position of the bridge 5 is designated as position B and the moving contacts (6) are 'sandwiched' between the fixed terminals (2) and shorting link (4), thus bridging the gap between them. The top housing (3) is adapted to encompass the whole switch when placed on the base housing (1).
8

In figure 2 the side view of the switching device in ON condition is illustrated. The two sets of moving contacts are shown by hatching and are numbered as 6a and 6b. The continuity is established in the electric circuit and the current flows from first fixed terminal (2a) to first set of moving contacts (6a) to shorting link (4) to second set of moving contacts (6b) and finally to second fixed terminal (2b) .
In figure 3 the front view of the switching device in OFF condition is illustrated. The moving bridge (5), which carries the moving contacts (6), is at position A. As a result of which, the fixed terminal (2) and the shorting link (4) in OFF condition get electrically separated. As there is no continuity, there is no current flow in the circuit.
In figure 4 the top view of the switching device in OFF condition is illustrated. The base housing (1) comprises guideway (8) adapted for lending a guided path for bridge (5).
Refer figure 3. During the transition of the switch from ON to OFF condition, the mechanism flips, the bridge is set in a sudden action and the set of moving contacts (6) adapted to break the electrical circuit is withdrawn from the fixed contacts, an arc is formed between the moving contacts (6) and shorting link (4) and also between the moving contacts (6) and the Terminal (2) . This is accompanied by the formation of a zone of ionized gases, surrounding the place of arcing. The effectiveness of the breaking capacity of the switch depends on the quenching of the arc so formed, which in turn depends on the speedy removal of these ionized gases and replenishing the
9

arcing zone with a block of fresh air, having better insulation properties.
As the bridge is suddenly set in motion, the extended projection (7) of the bridge carries out the following two functions.
Firstly, the extended projection typically of the length of order of 25-35 mm, moves in a sliding manner towards the arcing zone (Space between 2 and 6 and that between 4 and 6) , thereby replacing the ionized gases in the arcing zone with a block of fresh, unionized air. Since this unionized air has a better insulation property as compared to the ionized air, this results in the rapid quenching of the arc. This action is achieved with the fact that there is no deterioration of any insulating material and a new block of fresh air is pumped in, every time the switch is made to break the circuit.
In addition, the extended projection serves a second purpose. Owing to a complete overlap between extended projection (7) and the inner surfaces of terminal (2) and shorting link (4), the extended projection (7) now acts as an arc shearing plate or an insulation sheath, and the arc cannot find a path to strike between the terminal (2) and shorting link (4); hence complete insulation is ensured which obviates any possibility of striking or stagnation of the arc between them after opening operation of the switch, especially when it is commissioned at higher operating voltages.
Since these two effects pertaining to a quad-break switch are achieved by making use of a feature of the moving bridge (the bridge being an inevitable in any switching device for
10

carrying contacts), there is no need of addition of any extra component/assembly in the switch, thus making this method the most economical and simple way of achieving efficient arc quenching.
Moreover, the desired effect is achieved without any separate control means wherein the aforesaid operation becomes independent of various other members in the device; as the extended projection is an integral feature of the bridge, it essentially comes into action every time the bridge is set in motion (and hence the contacts are broken), giving a complete reliability of operation.
The invention has been shown and described in a preferred form only, and by way of example, and many variations may be made in the invention, which will still be comprised within its spirit. It is understood, therefore, that the invention is not limited to the details cited above. There may be a set of fuses, or any other overload safety devices integrated in the said design, which will then act as a switch-disconnector-fuse. Though four-pole design is mentioned, two or three pole design, if required, may easily be designed on the similar lines. Further, it is to be appreciated that the desired effect can also be achieved by varying the profile of the extended projection (7).
11

WE CLAIM
1. An enhanced switching device having improved performance
and switching potentiality, said device comprising :
housing;
plurality of electrical contacts received in said
housing, said contacts comprising moving contact system
wherein said moving contact system being spring assisted
operatively connected to a movable bridge means being
slidable so as to accommodate fluid adapted to provide
insulation in the device;
wherein said moving bridge comprises plurality of
ergonomical projections having predetermined dimensions
located and extended in a manner that the path of the arc
travel is blocked
thereby obviating any possibility of striking or
stagnation of the arc between them after opening
operation of the switch.
2. An enhanced switching device as claimed in claim 1, wherein length of the extended projection is kept adequate so as to span the entire width of fixed contacts thereby completely insulating them from each other.
3. An enhanced switching device as claimed in claims 1 and 2, wherein length of the projection ranges from 25 to 35 mm.
4. An enhanced switching device as claimed in' claims 1, wherein moving bridge being operatively connected to said
12

projections in a manner the sliding motion of moving bridge is adapted to generate sufficient space to accommodate unionized air providing improved insulation.
5. A method of achieving improved quenching of the arc, said method comprising :
replacement of ionized fluid with an unionized fluid so
as to suppress arc; and
blocking path of arc striking the terminals
in the switching device.
7. An enhanced switching device as herein substantially described and illustrated with reference to the accompanying figures.
Dated this 17th day of October, 2006.
Abhishek Sen Of S. Majumdar & Co. Applicant's Agent
13

ABSTRACT
TITLE : AN ENHANCED ELECTRICAL SWITCHING DEVICE WITH
INSULATION SHEATH FOR ARC SHEARING AND A METHOD OF ACHIEVING SUPERIOR ARC QUENCHING THEREOF
The present invention relates to an enhanced switching device having improved performance and switching potentiality. The device comprises housing (1,3), plurality of electrical contacts comprising moving contact system (6). Moving contact system (6) is spring assisted operatively connected to a movable bridge means (5) being slidable so as to accommodate fluid adapted to provide insulation in the device and comprises plurality of ergonomical projections (7) to obviate any possibility of striking or stagnation of the arc. Invention also relates to a method of achieving improved quenching of the arc where ionized fluid is replaced with an unionized fluid and path of arc striking the terminals is blocked.
Figure 3

APPLICANT : LARSEN & TOUBRO LIMITED

4 SHEETS SHEET 1

FIGURE 1

Abhishek Sen
OfS.MAJUMDAR&CO.
(Applicant's Agent)

APPLICANT : LARSEN & TOUBRO LIMITED

4 SHEETS SHEET 2

FIGURE 2

Abhishek Sen
Of S. MAJUMDAR & CO.
(Applicant's Agent)

APPLICANT : LARSEN & TOUBRO LIMITED

4 SHEETS SHEET 3

■R
\ }

V-TT

FIGURE 3

Abhishek Sen
Of S. MAJUMDAR & CO.
(Applicant's Agent)

APPLICANT : LARSEN & TOUBRO LIMITED

4 SHEETS SHEET 4

FIGURE 4

Abhishek Sen
OfS.MAJUMDAR&CO.
(Applicant's Agent)

Documents:

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Patent Number

272548

Indian Patent Application Number

1735/MUM/2006

PG Journal Number

15/2016

Publication Date

08-Apr-2016

Grant Date

07-Apr-2016

Date of Filing

19-Oct-2006

Name of Patentee

LARSEN & TOUBRO LIMITED

Applicant Address

L & T HOUSE, BALLARD ESTATE, MUMBAI

Inventors:

#	Inventor's Name	Inventor's Address
1	ANDHARE, VISHNU	SWITCHGEAR DESIGN & PRODUCT DEVELOPMENT CENTER, LARSEN & TOUBRO LIMITED, ELECTRICAL SECTOR- (EBG), POWAI WORKS (EAST), GATE NO. 7, SAKI VIHAR ROAD, MUMBAI 400 072,

PCT International Classification Number

H01H1/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA