DESC:TECHNICAL FIELD OF THE INVENTION
This invention relates generally to arc chutes in circuit breakers. More particularly, the present invention relates to an improved arc chute assembly having a tapered de-ion plate profile that results in better aerodynamic flow of sonic waves and arc gases thereby providing better arc quenching. This invention is for use in switchgear industries.

BACKGROUND AND THE PRIOR ART
Opening of a live contact in a circuit results in development of an electric arc. The contacts of a circuit breaker experience the same during its opening i.e. an arc is formed between the contacts when they separate in order to interrupt a live circuit. The technology used in switchgears for arc quenching makes use of an arc quenching chamber for lengthening and splitting of arc. The faster the arc is quenched the lesser the damage of contacts. An arc chute is designed with this particular intention. In order to further improve the arc quenching performance, the profile of the de-ion plates are such that the sonic waves produced during arc formation are aerodynamically made to flow towards the top of the chamber, hence quenching the arc faster.

Some of the prior arts in the present field of invention are as follows:

US2011290761A1discloses an arc chute for a medium voltage circuit breaker having a housing, at least one stack of a plurality of substantially parallel metal plates arranged in the housing, the at least one stack defining a first axis in parallel to a stacking direction; an arc space arranged in the housing, wherein the arc space is adapted to allow an arc to expand therein; and at least one arc quenching plate disposed in the housing, wherein the arc guiding plate has at least one surface which has a surface plane extending in parallel to the first axis. Further, the present disclosure relates to a circuit breaker having a switching unit with a first switch contact and a second switch contact, movable between a first position, wherein the first switch contact contacts the second switch contact, and a second position, wherein the first switch contact is separated from the second switch contact, and an arc chute. Additionally, the disclosure relates to a polymer plate selected of a group containing a flame retardant polymer, a flame retardant polymer having flame retardant filler, and a polymer having flame retardant filler as an arc quenching plate.

RU2306629 C1 proposed arc-control device that can be used in high-speed circuit breakers for overload and short-circuit protection of electrical equipment, for instance that of DC consists, is made in the form of arc chute that has external walls with arc-control horns between them and de-ion grids tilted through certain angle to one another and assembled of steel plates with air gaps between them. Flame-retardant grids are installed along de-ion grids at arc chute outlet. Holes are provided in external walls of arc chute in vicinity of de-ion grids. Provision is made for regulating aerodynamic factors occurring in the course of arc quenching due to elimination of ionized gas flow toward circuit-breaker contact group. It reduced size of arc chute, enhanced switching capacity of high-speed circuit breaker

GB951512A disclosed an arc-chute having spaced conducing plates arranged transversely to the arc, the plates have one or more holes shaped or arranged so that the area of the hole or holes decreases in the direction of travel of the arc towards the exhaust end of the chute. This is stated to facilitate the entry of the arc into the plates and its rooting on to the plates. The holes 3 may be equal in size and diminish in number towards the exhaust end of the chute, or may diminish in size towards the exhaust end of the chute. They may be circular as shown or triangular in shape, or a single triangular hole may be provided. The plates are bent into a U-shape to form limbs having the holes and shorter limbs. When the arc root on to the limbs the current flowing through the bases of the U-shaped plates sets up a magnetic field which acts to prevent the arc being blown out of the arc chute.

CA2049263A1 disclosed a molded case circuit breaker of the type using electrodynamic repulsion to separate the circuit breaker contacts under intense overcurrent conditions also includes an arc chute arrangement for cooling and quenching the arc that occurs during such contact separation. A plastic cover insert added to the interior of the circuit breaker cover multi-functionally retains the arc chute within the circuit breaker case while providing clearance for the circuit breaker operating handle shutter. A resilient pad on the top surface of the cover insert receives the circuit breaker operating handle skirt upon contact separation and dampens the energy imparted to the operating handle and to the circuit breaker cover.

EP1876615 disclosed a contact assembly for a circuit breaker includes a fixed contact, a movable contact, and a movable contact arm. The movable contact arm includes a first end carrying the movable contact, a second end, and a pivot portion proximate the second end. A moving arm portion extends from the first end toward the pivot portion. The moving arm portion has a width, an upper edge, a lower edge, and a height defined by the distance between the upper edge and the lower edge. In response to a trip condition, the movable contact separates from the fixed contact and the movable contact arm pivots open at an angular opening velocity. The height of the moving arm portion of the movable contact arm is at least four times the width of the moving arm portion, thus minimizing the moment-of-inertia of the movable contact arm, and increasing the angular opening velocity

EP1228518 disclosed a current limiting circuit breaker mechanism having two pairs of separable contacts closely spaced for electro dynamic repulsion upon the occurrence of a short circuit overload condition utilizes a pair of arc chute assemblies to cool and extinguish the arc that occurs when the contacts become separated. The arc chute assemblies contain a plurality of arc chute plates supported by side supports. The arc chute plates are aerodynamically designed to facilitate the easy flow of the arc plasma gases into and out of the chute and provide minimal reflection of the arc plasma wave against the contact arm

US6248970B1 provides a circuit breaker including an electrical arc extinguishing apparatus. The electric arc extinguishing arc apparatus includes a first sidewall in a spaced relationship with the second sidewall with a top arc plate mounted between the first and second sidewalls. A plurality of intermediate arc plates is mounted between the first and second sidewalls below the top arc plate with each in a spaced apart relationship. A bottom arc plate is mounted between the first and second sidewalls below and apart from the intermediate plates forming an arc chute. The electric arc extinguishing apparatus can also be provided with two end caps with each end cap having an interior cavity with one leg of each arc plate mounted in the cavity of one end cap and the other leg of each arc plate mounted in the cavity of the other end cap.

US2003062341A1 provides arc quenching device for an air-switching low-voltage switching device includes quenching plates, which are arranged between and attached to parallel insulating walls, as well as a cover. A separate cooling device may be introduced into the space between the quenching plates and the cover. The cooling device is in the form of an insert cartridge and contains deionization technology for switching gases. Attachment pins on the cooling device and corresponding holding openings on the inside of the cover make it possible to fit the cooling device to the cover before this cover engages with the insulating walls.

The disadvantage of the current technology is that the sonic waves and arc gases produced during arc formation are reflected back onto the region near the contacts. This leads to further heating of the medium between the contacts. As a result the de-ionization of the medium becomes tougher and arc quenching takes more time, thereby causing damage to the contacts.

Tapering is provided on the profile side of the plate. This invention prevents reflection of the sonic waves back onto the region between the contacts and better aerodynamic movement of the sonic waves produced towards the arc chute top. Therefore it results in better cooling of the chamber and hence quicker arc quenching and hence lesser erosion and damage of the contacts.

This invention relates, in general, to clearing fault currents using arc quenching technologies in switchgears. The product of invention is an improvised Arc chute, which by the virtue of its design results in better aerodynamic flow of sonic waves and arc gases and hence results in better arc quenching. This invention is for use in switchgear industries.

OBJECTS OF THE INVENTION

A basic object of the present invention is to overcome the disadvantages/drawbacks of the known art.

Another object of the present invention is to provide an improved arc chute assembly.

Other object of the present invention is to provide a tapered de-ion plate profile that results in better aerodynamic flow of sonic waves and arc gases thereby providing better arc quenching.

Other object of the present invention is to provide means in an arc quenching chamber for lengthening and splitting of arc.

Yet another object of the present invention is to reduce the erosion on the contacts and improve the life of the breaker.

These and other advantages of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

There is provided an improved arc chute assembly having a tapered de-ion plate profile that results in better aerodynamic flow of sonic waves and arc gases thereby providing better arc quenching.

According to one aspect of the present invention, there is provided an arc chute assembly consisting of de-ion plates made of mild steel and zinc plated. The plates are placed adjacent to each other and with a certain gap between them. The plates are crimped on to the side plate made of glass filled polyester. The de-ion plates attract the electric arc by the virtue of their ferromagnetic property. The de-ion plates with the specific profile exert more electromagnetic pull on the electric arc. During the arc formation, sonic waves and arc gases are produced. The arc gases produced, contribute to a great extent in the heating up of the chamber, resulting in increased number of collisions between neutral atoms and hence increased formation of free electrons. Therefore dielectric breakdown of the medium takes place and hence electrical isolation which is the primary function of the product is affected. The invention deals with tapering of the de-ion plates. The profile of each of the de-ion plates, facing towards the contacts, is tapered. As a result, sonic waves and arc gases movement towards the top of the arc chamber is facilitated. Also due to tapering sonic waves and arc gases reflection back onto the contact region is prevented. Hence due to reduced temperature of the contact region, de-ionization of the chamber becomes easier and arc quenching times are reduced to a large extent.

Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The following drawings are illustrative of particular examples for enabling methods of the present invention, are descriptive of some of the methods, and are not intended to limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description.

Reference is first invited to FIG. 1 where top and side view in 3D OF Arc chute according to one aspect of this invention is shown.

FIG. 2 shows the front view of de-ion plate according to an aspect of this invention.

FIG. 3 shows cross sectional view of the arc chute according to an aspect of this invention.

FIG. 4 shows front view of the cross section to an embodiment of this invention in arc chute.

FIG. 5 shows detailed view in 3D of de-ion plate profile and tapering done according to an embodiment of this invention in arc chute.

FIG. 6 shows detailed view in 3D of de-ion plate profile and tapering done according to an embodiment of this invention in arc chute.

Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure.
Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE INVENTION

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

Accordingly the present invention provides a tapered profile of the de-ion ion plates. Tapering is provided on the profile side of the plate. This invention prevents reflection of the sonic waves back onto the region between the contacts and better aerodynamic movement of the sonic waves produced towards the arc chute top. It results in better cooling of the chamber and hence quicker arc quenching and hence lesser erosion and damage of the contacts.

The current invention is on the ‘arc chute’(fig 1), which is a component used in switchgear products. A circuit breaker is a device used in order to clear a fault current. Whenever fault current flows in the system, the circuit breaker used is expected to clear the fault with minimal damage to itself. Opening of the contacts of a circuit breaker results in the formation of an electric arc between the contacts. The electric arc erodes the contacts and henceforth reduces the life of the circuit breaker. Therefore the design of arcing chamber needs to be as effective as possible and arc chutes play a paramount role in it.

The arc chute designed consists of de-ion plates (2) made of mild steel and zinc plated (fig 2). The plates are placed adjacent to each other and with a certain gap between them (fig 3). The plates are crimped on to the side plate made of glass filled polyester. The de-ion plates attract the electric arc by the virtue of their ferromagnetic property. The de-ion plates with the specific profile exert more electromagnetic pull on the electric arc (fig 4). During the arc formation, sonic waves and arc gases are produced. The arc gases produced, contribute to a great extent in the heating up of the chamber, resulting in increased number of collisions between neutral atoms and hence increased formation of free electrons. Therefore dielectric breakdown of the medium takes place and hence electrical isolation which is the primary function of the product is affected.

The invention deals with tapering of the de-ion plates. The profile (1) of each of the de-ion plates, facing towards the contacts, is tapered (fig 5 & fig 6). As a result, sonic waves and arc gases movement towards the top of the arc chamber is facilitated. Also due to tapering sonic waves and arc gases reflection back onto the contact region is prevented.

Hence due to reduced temperature of the contact region, de-ionization of the chamber becomes easier and arc quenching times are reduced by a large extent. Advantage of quicker arc quenching is that the erosion on the contacts is lesser and hence the life of the breaker is significantly improved. ,CLAIMS:1. An improved arc chute assembly for use in circuit breakers, said assembly comprises:
de-ion plate arrangement comprising plural de-ion plates;
characterized in that each of said de-ion plates comprising a tapered profile on one end of the said plate so as to prevent reflection of the sonic waves back onto the region between the contacts of the circuit breaker and provide better aerodynamic movement of the sonic waves produced towards the arc chute top.

2. Assembly as claimed in claim 1 wherein said tapered profile comprises pointed edge to define an aerodynamic profile.

3. Assembly as claimed in claim 1 wherein said de-ion plates are made of mild steel.

4. Assembly as claimed in claim 1 wherein said de-ion plates are zinc plated.

5. Assembly as claimed in claim 1 wherein said tapered profile of the de-ion plates points towards the contacts.

6. Assembly as claimed in claim 1 further comprising at least one de-ion plate having flat end facing the contacts.