Claims:Field of invention:

The present invention relates to electrical switching devices/ circuit breakersand more particularly, to an arc chute assembly for quenching an arc in the electrical switching device.

Backgroundof the invention:

An arc chute assembly is also referred as an arc extinguishing unit. The arc chute assembly is an integral part of an electrical switching device forquenching an arc.Conventional electrical switching device / circuit breaker consists of aninsulated material as casing, a pair of separable contacts and the arc chute assembly. The conventional system of the arc chute assembly comprises of ferromagnetic plates of ferromagnetic material stacked in a way, with the help of lining/wall. The arc chute assembly helps in quenching the arc generated during switching offthe electrical switching device, by elongating, splitting, thus cooling the arc. The function of the ferromagnetic plate is to split the arc, thereby resulting in buildup of arc voltage and consequently greater dielectric strength.

In prior art, US3005892 patent relates to arc chutes for air immersed circuit breakers. More particularly, the prior art patent is directed to a dual flow arc chute whereby degree of turbulence within the arc chute is substantially increased to thereby aid in the de-ionization of gases and eliminate possibility of creating a conducting path to the grounding housing.

Another prior art patent application US 20140151340 generally relates to an arc chute arrangement for arc quenching in the electrical switching devices. The arc chute consists of stack of deion plates made up of magnetic material to attract, split-up and cool the arcs. The stack of deion plates is trapped in between two plates known as lining made up of electrically insulating material. The function of deion plates is to split the arc in several series arcs of approximately equal length that results in higher arc voltage and distinctly greater dielectric strength after current zero.

Another US prior art patent US 4107497 is provided with an arc chute assembly for circuit interrupting devices, wherein the parts thereof are positively and reliable maintained in assembled relation without staking. The elimination of staking obviates the need for the fixturing requiring in a staking operation. Also, the occasional destruction of arc chute parts during a staking operation, particularly the insulative side plates to which the arc plates are normally staked, is avoided.

However, the arc chute assembly of the prior arts has various drawbacks. Due the absence of ablative material in the arc chute assembly, the arc takes longer time to quench that may lead to the erosion of ferromagnetic plates, thus reducing the thermal mass, deteriorating the performance, life of the electrical switching device / circuit breaker. There is a possibility that the arc can flash-over or re-strike at the end of the ferromagnetic plates stack, thus preventing the arc voltage build up and aggravation of the short-circuit performance. The conventional arc chute assembly also has a possibility of collapsing of the arc chute assembly due to high pressure inside the arcing chamber, during the course of the short-circuit faults, which leads to the poor performance of the electrical switching device / circuit breaker.

Accordingly, there is a need to provide improved design of the arc chute assembly that overcomes above mentioned drawbacks in the prior art.

Objects of the invention:

An object of the present invention is to improve design of an arc chute assembly for arc quenchingby providing dual manner assembly of arc plates in an electrical switching device.

Another object of the present invention is to achievemore stability of the arc plates stack in the arc chute assembly.

Yet, another object of the present invention is to avoid collapsing of the arc chute assembly.

Summary of the invention:

Accordingly, the present invention provides an arc chute assemblyfor an electrical switching device. The arc chute assembly comprises of a casing, a plurality of arc plates, a pair of arc deflectors and a rib. The casing has a top section, a bottom section and an internal wall. The casing further includes a first set of guiding ribs configured on the internal wall at the bottom section, a second set of guiding ribs configured on the internal wall at the top section,a first set of stoppers configured at a front side of the bottom section anda second set of stoppers configured at a back side of the top section. The casing allows dual manner assembly of the plurality of arc plates in substantial parallel wayfor producing force of attraction during arcing.

The plurality of arc plates includes a first stack arranged at the bottom section of the casing and a second stack arranged at the top section of the casing. The first stack is inserted from a back side of the bottom section till reach the first set of stoppers. The plurality of arc plates of the first stack is pushed at the bottom section of the casing with the help of the first set of guiding ribs. Thereinafter, the second stack is inserted from a front side of the top section till reach the second set of stoppers and is guided by second set of guiding ribs. After the insertion of the plurality of arc plates of the first stack inside the casing, the plurality of arc plates of the second stack are pushed at the top section of the casing with the help of the second set of guiding ribs. The plurality of arc plates of the first stack is assembled in opposite direction to that of the plurality of arc plates of the second stack inside the casing. The movement of the plurality of arc plates is constrained with the help of the first set of guiding ribs and the second set of guiding ribs. An each arc plate of the second stack includes a pair of notches configured thereon. The plurality of the arc plates is made up of ferromagnetic material and is same throughout the arc chute assembly with no difference in the structure/construction and the material. The first set of stoppers and the second set of stoppers keep the plurality of arc plates intact in desired position inside the casing, thereby avoiding lateral movement of the plurality of arc plates.

The pair of arc deflectors is fitted on the front side of the top section of the casing by holding the plurality of arc plates of the second stack using the pairs of notches. The pair of arc deflectors prevents the arcing and dielectric breakdown. An each of the arc deflectors includes a plurality of ribs configured thereon for facilitating fitting of the pair of arc deflectors inside spacing between the plurality of arc plates of the second stack. The pair of arc deflectors is detachable external componentthat is coupled with the casing in an inserted manner.The first set of stoppers and the second set of stoppers along with the pair of arc deflectors provide structural stability to the arc chute assembly.

The rib is configured on a top surface of the casing for facilitating fitment of the arc chute assembly inside an arcing chamber of the electrical switching device. The casing and the pair of arc deflectors are made up of an electrically insulating material having an ablative material that emits electronegative gases during high temperature condition and absorbs charged particles from an arc, thereby enhancing pressure of the arcing chamber to provide faster movement of the arc in the arc chute.

Brief description of the drawings:

Figure 1 shows a front perspective view of a casing of an arc chute assembly, in accordance with the present invention;

Figure 2 shows a back perspective view of the casing of the arc chute assembly, in accordance with the present invention;

Figure 3 shows the back perspective view of the arc chute assembly for insertion of bottom arc plates,in accordance with the present invention;

Figure 4 shows thefront perspective view of the arc chute assembly for insertion of top arc plates, in accordance with the present invention;

Figure 5 shows assembling of an arc deflector post assembly of the arc plates in the arc chute assembly, in accordance with the present invention; and

Figure 6 shows finalperspective view of the arc chute assembly, in accordance with the present invention.

Detailed description of the embodiments of the invention:

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.

The present invention provides an arc chute assembly for quenching an arc in an electrical switching device. The arc chute assemblyprovides assembly of arc plates in dual manner insidea casingto achieve better functional performance. Some arc plates are stacked in the casing from one side and the remaining arc plates from the other side of the casing. Thearc chute assembly additionally includes an arc deflectorcoupled in an inserted manner. The arc chute assembly facilitates stable operation structurally and avoidscollapsing of an arc chute, thereby providing rigidity of the arc chute in an arc chamber of the electrical switching device during short circuit faults.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.

Referring to figures 1 to 6, an arc chute assembly (100) for an electrical switching device (not shown) in accordance with the present invention is shown. The arc chute assembly (100) comprises of a casing (50), a plurality of arc plates (80), a pair of arc deflectors (90) and a rib (95). The casing includes a top section (not numbered), a bottom section (not numbered) and an internal wall (not numbered). Further, the casing includes a first set of guiding ribs (10) (refer fig. 2) configured on the internal wall at the bottom section, a second set of guiding ribs (20) (refer fig. 1) configured on the internal wall at the top section, a first set of stoppers (30)(refer fig. 1) configured at a front side of the bottom section and a second set of stoppers (40) (refer fig. 2) configured at a back side of the top section. The casing (50) is designed in such a way that allows dual manner assembly of the plurality of arc plates (80) therein.The plurality of arc plates (80) isassembled in substantial parallel wayfor producing force of attraction during arcing.In an embodiment, the casing (50) is made up of an electrically insulating material.

The plurality of arc plates (80) includes a first stack (60) arranged at the bottom section of the casing (50) and a second stack (70) arranged at the top section of the casing (50). The first stack (60) is inserted from a back side of the bottom section till reach the first set of stoppers (30). The first stack (60) is guided by the first set of guiding ribs (10). The plurality of arc plates of the first stack (60) are pushed at the bottom section with the help of the first set of guiding ribs (10) till reach the first set of stoppers (30) (refer fig. 3). After the insertion of the plurality of arc plates of the first stack (60) inside the casing (50), the second stack (70) is inserted from a front side of the top section till reach the second set of stoppers (40) (refer fig. 4). The second stack (70) is guided by the second set of guiding ribs (20). The plurality of arc plates of the second stack (70) are pushed at the top section with the help of the second set of guiding ribs (20) till reach the second set of stoppers (40). In a preferred embodiment, the plurality of arc plates of the first stack (60) are assembled in opposite direction to that of the plurality of arc plates of the second stack (70) inside the casing (50). The movement of the plurality of arc plates (80) is constrained with the help of the first set of guiding ribs (10) and the second set of guiding ribs (20).An each arc plate of the second stack (70) includes a pair of notches (65) configured thereon. In the embodiment, the plurality of the arc plates (80) is made up of ferromagnetic material and is same throughout the arc chute assembly (100) with no difference in the structure/construction and the material. The first set of stoppers (30) and the second set of stoppers (40) keep the plurality of arc plates (80) intact in desired position inside the casing (50), thereby avoiding lateral movement of the plurality of arc plates (80).

The pair of arc deflectors (90) is fitted on the front side of the top section of the casing (50) by holding the plurality of arc plates of the second stack (70) using the pairs of notches (65) (refer fig. 5). The pair of arc deflectors (90) prevents the arcing and dielectric breakdown. An each of the arc deflectors (90) includes a plurality of ribs (85) configured thereon. The plurality of ribs (85) facilitates fitting of the pair of arc deflectors (90) inside spacing between the plurality of arc plates of the second stack (70). In a specific embodiment, the pair of arc deflectors (90) is detachable external componentthat is coupled with the casing (50) in an inserted manner.In the embodiment, the pair of arc deflectors (90) is made up of the electrically insulating material. The first set of stoppers (30) and the second set of stoppers (40) along with the pair of arc deflectors (90) provide structural stability to the arc chute assembly (100).

The rib (95) is configured on a top surface of the casing (50). The rib (95) facilitates fitment of the arc chute assembly (100) inside an arcing chamber (not shown) of the electrical switching device.

The casing (50) and the pair of arc deflectors (90) are made up of the electrically insulating material having an ablative material (gassing material). The ablative material emits electronegative gases during short circuit, inside the arcing chamber, thereby releasing electronegative ions. The electronegative ions absorb the charged particles form the arc released during the arcing, thereby reducing the intensity of ions in the arcing chamber and increases the dielectric strength, which improves the arc quenching performance .The ablative material emits gases only in high temperature condition i.e. during short circuit. This facilitates rapid buildup of the of an arc voltage. This also, helps in the fast recovery of the di-electric strength of arcing zone and hence lesser arc splitting time.

The arc chute assembly (100) improves the overall performance in arc quenching.

Advantages of the invention:

1. The arc chute assembly (100) provides stability in terms of the position of the plurality of arc plates (80), the spacing between the plurality of arc plates (80).
2. The dual manner of the plurality of arc plates (80) along with the pair of arc deflectors (90) provide structural stability to the arc chute assembly (100) preventing the collapse of the plurality of arc plates (80) during short circuit faults, due to high pressure and temperature.
3. The casing (50) and the pair of arc deflectors (90) emit the ablative gasses during arcing.
4. During short circuit fault, after the contact separation, the arc enters the arc chute assembly (100) and splits in the number of series of arcs. The fault current flowing through the contacts produces a magnetic field in the ferromagnetic plates. Magnetic field lines produce a force of attraction, pulling the arc inside the ferromagnetic plates. The force acting on the arc due to gas pressure generated inside the arcing chamber also pushes the arc inside the arc chute.Moreover, the arc chute assembly (100) made up of ablative material releases the gasses and enhances the gas pressure inside the arcing chamber that produces more force acting on the arc pushing the arc inside the arc chute.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.

, Description:We claim:

1. An arc chute assembly (100) for anelectrical switching device comprising:
a casing (50) havinga top section,a bottom section and an internal wall, wherein the casing (50) further includes,
• a first set of guiding ribs (10) configured on the internal wall at the bottom section,
• a second set of guiding ribs (20) configured on the internal wall at the top section,
• a first set of stoppers (30) configured at a front side of the bottom section, and
• a second set of stoppers (40) configured at a back side of the top section;
a plurality of arc plates (80) having,
• afirst stack (60) arranged at thebottomsectionof the casing (50), wherein the first stack (60) is inserted from a back side of the bottom section till reach the first set of stoppers (30) and is guided by first set of guiding ribs (10);
• a second stack (70) arranged at the top section of the casing (50), wherein the second stack (70) is inserted from a front side of the top section till reach the second set of stoppers (40) and is guided by second set of guiding ribs (20) and further wherein, each arc plate of the second stack (70) includes a pair of notches (65) configured thereon;
a pair of arc deflectors (90)fitted on the front side of the top section by holding the second stack (70) using the pairs of notches (65) to prevent the arcing and dielectric breakdown, wherein each of the arc deflectors (90) includesa plurality ofribs (85) configured thereon for facilitating fitting of the pair of arc deflectors (90) inside spacing between the plurality of arc plates of the second stack (70); and
a rib (95) configured on a top surface of the casing (50) for facilitating fitment of the arc chute assembly (100) inside an arcing chamber of the electrical switching device.

2. The arc chute assembly (100) as claimed in claim 1, wherein the casing (50) allows dual manner assembly of the plurality of arc plates (80)in substantial parallel wayfor producing force of attraction during arcing.

3. The arc chute assembly (100) as claimed in claim 1, wherein the plurality of arc plates of the first stack (60) are pushed at the bottom section of the casing (50) with the help of the first set of guiding ribs (10)till reach the first set of stoppers (30) and after the insertion of the plurality of arc plates of the first stack (60) inside the casing (50), the plurality of arc plates of the second stack (70) are pushed at the top section of the casing (50) with the help of the second set of guiding ribs (20) till reach the second set of stoppers (40).

4. The arc chute assembly (100) as claimed in claim 1, wherein the plurality of arc plates of the first stack (60) are assembled in opposite direction to that of the plurality of arc plates of the second stack (70) inside the casing (50).

5. The arc chute assembly (100) as claimed in claim 1, wherein the movement of the plurality of arc plates (80) is constrained with the help of the first set of guiding ribs (10) and the second set of guiding ribs (20).

6. The arc chute assembly (100) as claimed in claim 1, wherein the first set of stoppers (30) and the second set of stoppers (40) keep the plurality of arc plates (80) intact in desired position inside the casing (50),thereby avoiding lateral movement of the plurality of arc plates (80).

7. The arc chute assembly (100) as claimed in claim 1, wherein the first set of stoppers (30) and the second set of stoppers (40) along with the pair of arc deflectors (90) provide structural stability to the arc chute assembly (100).

8. The arc chute assembly (100) as claimed in claim 1, wherein the pair of arc deflectors (90) is detachable external component that is coupled with the casing (50) in an inserted manner.

9. The arc chute assembly (100) as claimed in claim 1, wherein the casing (50) and the pair of arc deflectors (90) are made up of anelectrically insulating material having an ablative material that emits electronegative gases during high temperature condition and absorbs charged particles from an arc, therebyenhancing pressure of the arcing chamber to provide faster movement of the arc in the arc chute.

10. The arc chute assembly (100) as claimed in claim 1, wherein the plurality of the arc plates (80) is made up of ferromagnetic materialand is same throughout the arc chute assembly (100) with no difference in the structure/construction and the material.