GB2273609A

GB2273609A - Circuit breaker with outlet for the arcing gases

Info

Publication number: GB2273609A
Application number: GB9325448A
Authority: GB
Inventors: Jean-Marc Finet; Michel Perrot; Jean-Claude Ramirez; Jean-Bruno Comino
Original assignee: Merlin Gerin SA
Current assignee: Merlin Gerin SA
Priority date: 1992-12-17
Filing date: 1993-12-13
Publication date: 1994-06-22
Anticipated expiration: 2013-12-13
Also published as: GB2273609B; FR2699730A1; GB9325448D0; FR2699730B1

Abstract

An electrical circuit breaker comprises a moulded insulating case (2) having a rear panel (4) and two lateral panels (6) extending frontwards from the rear panel and housing a main arc extinguishing chamber with deionisation plates producing arcing gases. A gas outlet part (32) of elongated shape is located on one of the lateral panels (6) to define an elongated gas outlet chamber having one closed end positioned adjacent to an opening in the lateral panel (6) communicating with the arc extinguishing chamber and an open end situated at the rear panel (4) of the case (2). <IMAGE>

Description

An electrical circuit breaker The present invention relates in a general manner to circuit breakers in the form of modular electrical switchgear designed to be included in a low-voltage or medium-voltage, industrial or domestic electrical installation. The invention relates more particularly to a miniature electrical circuit breaker comprising a moulded insulating case, of general parallelepipedic shape, having a rear fixing panel, arranged on a rear face of the case, and two lateral panels extending frontwards from the rear panel, said case housing a main arc extinguishing chamber with deionisation plates.

The document FR-A-2,663,458 relates to a miniature electrical circuit breaker of a type described above. In this prior art circuit breaker, a decompression chamber is in addition provided so that the outlet of the main chamber communicates with the outside, this outlet being achieved via an outlet orifice which is situated at the level of the fixing panel. In addition, in this prior art circuit breaker, the decompression chamber comprises a baffle which is situated near the outlet orifice.

This prior art circuit breaker has tne advantage that the breaking gases are outlet from the circuit breaker case at the level cf its rear panel, and consequently the breaking gases are thus diverted to a rear zone not containing any live active parts.Thus, tis arrangement enables the reliabilitv of the circuit breaker to oe improved while reducing the possibilities of electrical flashovers at the level ot tne live active parts external to the circuit breaker, in particular the level of the external connection =erials and electrical connecting wires, because there are in general no live active parts located near the rsr panel of the circuit breaker.

However, in a pricr art circuit breaker ci tis knd, the space available between the main chamber and rear panel is relatively small, in particular the distance separating the zone through which the gases are outlet from the main chamber and the orifice arranged for outlet through the rear panel is relatively small, for example about 8 to 15mm. Furthermore, this decompression chamber is limited by internal walls the sum of whose surfaces remains relatively small. The baffle which is provided inside this decompression chamber remains relatively inefficient because it is located in too small a space and because it is too close to the zone through which the gases are outlet from the main chamber.This results in the gases which are outlet via the outlet orifice arranged in the rear panel remaining relatively hot and dense, these gases thus being able to create electrical discharges and also being able to make certain parts of the circuit breaker case age prematurely, in particular parts of the case made of plastic material situated at the level of the decompression chamber and at the level of, or near to, the rear panel outlet orifice.

The present invention seeks to provide a miniature electrical circuit breaker in which the gases produced in the main arc extinguishing chamber are more efficiently decompressed.

Further, the present invention seeks to provide a circuit breaker in which a more efficient decompression chamber is provided, without however resulting in an increased complexity.

Additionally, the present invention seeks to provide a circuit breaker having a decompression chamber sufficiently efficient to be able not to comprise an outlet orifice.

Moreover, the present invention seeks to provide a circuit breaker in which an outlet orifice of the decompression chamber can easily be arranged in a part of the rear panel, at a position on the rear panel situated at a relatively large distance from the zone through which the gases are outlet from the main chamber.

Accordingly, the present invention provides an electrical circuit breaker comprising a moulded insulating case having a rear panel and two lateral panels extending frontwards from the rear panel, said case housing a main arc extinguishing chamber with deionisation plates producing breaking gases, which electrical circuit breaker further comprises: an opening arranged in one of said lateral panels, opening out into said main chamber; and a gas outlet part of elongated shape, comprising a recess arranged longitudinally in a lateral face of the outlet part, the recess opening out longitudinally only at the level of one of the ends of the outlet part, the outlet part having its said one lateral face applied against said lateral panel of the case in such a way as to constitute with this lateral panel an elongated gas outlet chamber having one closed end and its other end open, said outlet part being positioned in such a way that said opening opens out into the gas outlet chamber near to its closed end and that its open end is situated at the level of said rear panel of the case.

According to a particular embodiment of the invention, the circuit breaker comprises in addition a cover which has the general shape of a flat plate and which is mounted laterally on said case in a manner parallel to said lateral panel of the case, said outlet part being secured between the cover and the lateral panel of the case.

According to another embodiment of the invention, said lateral panel of the case comprises on its external face ribs of such a kind that said outlet part is applied against the lateral panel of the case and cooperates with these ribs so that these ribs hold the outlet part in position and contribute to the tightness between the outlet part and the case.

According to a further embodiment of the invention, said gas outlet chamber is of a general shape which is elongated and curved in a plane parallel to the plane of the lateral panel of the case so that the distance covered by the gases along the outlet chamber is increased.

In another alternative embodiment of the invention, said gas outlet chamber is of a shape which is elongated and curved in a plane parallel to the plane of the lateral panel of the case so that the gases which flow along the outlet chamber exit from the outlet chamber in an outlet direction appreciably perpendicular to the external face of said rear panel of the case.

These objects, advantages and features, among others, of the present invention, will become more clearly apparent from the following detailed description of Illustrative embodiments, represented in the accompanying drawings in which figure 1 is a side view of a circuit breaker according to the invention, certain parts and pieces cf parts having been removed in order to show certain internal details of the circuit breaker; figure 2 is a similar view to that cf fizzle 1 but in which different parts and pieces of parts have been removed in order to show other details of the same circuit breaker according to the invention;; figure 3 is a similar view to that of figure 2 but in which one of the parts removed in figure 2 has been put back, in order to show further details of the same circuit breaker according to the invention; figure 4 is a partial cross-sectional view along the line IV-IV of figure 3, in which all the parts or pieces of parts are present; figure 5 is a partial cross-section view along the line V-V of figure 3, in which all the parts or pieces of parts are present; and figure 6 is a similar view to that of figure 4 but concerning an alternative embodiment of the circuit breaker according to the invention.

In figures 1, 2 and 3, a single circuit breaker according to the present invention is represented. These three figures differ only in the fact that from one figure to another certain parts or pieces of parts have been removed differently in order to reveal certain internal parts of the device more easily. Referring to figures 1 and 4, it can be seen that the circuit breaker comprises a case 2 which has a general parallelepipedic shape and which is generally made of insulating plastic material. The case 2 comprises a rear panel 4 (figure 5) which serves the purpose of fixing the circuit breaker and two lateral panel 6 (only one is visible in figures 1 to 5), these two lateral panels extending frontwards from the rear panel 4. The case 2 also has a top panel 8, a bottom panel 10 and a front panel 12.The panels 4,8,10 and 12 consequently join the two lateral panels 6 so as to constitute the general parallelepipedic shape of the case 2. The case 2 houses a conventional circuit breaker mechanism assembly and in particular it houses a main arc extinguishing chamber 14 (figure 1) which comprises a certain number of deionisation plates 16 located between two conducting components 18 and 20. On the lateral panel 6 there is arranged an opening 22 (figure 2) which opens into the main chamber 14 and which enables the breaking gases to be outlet via this opening 22. Consequently, the breaking gases generated in the main chamber 14 are outlet laterally via the opening 22 arranged in the lateral panel 6.

The case 2 comprises in addition at the level of the lateral panel 6 a raised surround 24 extending radially outwards from the lateral panel 6 and whose external edge 26 is designed to receive a lateral cover 28 in conventional manner. Consequently, when the cover 28 is fitted against the edge 26, the assembly forms a lateral space 30 which is appreciably closed and which extends between the lateral panel 6 and the cover 28 over a relatively small thickness, for example comprised between 3 and 8 mm.

As can be seen in figures 3, 4 and 5, there is located in the lateral space 30 a gas outlet part 32 which is described in detail hereafter. The gas outlet part 32 has the general shape of a trunking, i.e. this part 32, as can be seen in the cress- sectional view of figure 5, has a reverse U-shaped cross-section over its whole length. The gas outlet part 32 thus has an elongated shape which extends from a zone situated above the opening 22 up to a zone situated at the level cf the external face of the rear panel 4, as can be seen in particular in figure 3.

As can be seen in figure 5, the gas outlet part 32 is applied against the external face of the lateral panel 6 of the case 2, in such a way that its hollowed internal part forms with the lateral panel 6 a chamber 34 which is hereinafter called "expansion chamber" as this chamber 34 is designed to expand the breaking gases which are produced in the main chamber 14 of the circuit breaker and which flow into the expansion chamber 34 via the opening 22. These breaking gases therefore enter the expansion chamber 34 at the level of the opening 22 and move along this chamber up to its open end 36 which is situated at the level of the external face of the rear panel 4 of the case 2. Consequently, the breaking gases are outlet from the circuit breaker at the level of its rear panel 4, as represented by the arrow in figure 3.

In figure 2, a top view of the circuit breaker can be seen in which the lateral panel 6 of the case 2 can be seen but in which the gas outlet part 32 has been removed. Arrows present in figure 2 indicate the path taken by the breaking gases from their outlet at the level of the opening 22 to the exit 36 from the expansion chamber 34. The gas outlet part 32 is fixed in a relatively tight manner to the lateral panel 6 by means of ribs 38, 40 which are arranged as protuberances on the external face of the lateral panel 6 and which enable the gas outlet part 32 to be fitted onto these ribs.These ribs 38, 40 moreover serve the purpose of positioning the gas outlet part 32 and of improving the tightness between the gas outlet part 32 and the lateral panel 6 of the case 2. Furthermore, as can be seen in figures 3 and 5, the gas cutlet part 32 comprises, in conventional manner, fixing lugs 42, 44, 46 each comprising a hole through which a stud 48 passes protruding out on the lateral panel 6.

In other words, it can be said that the gas cutlet part 32 is of elongated shape, comprising a recess 31 arranged longitudinall in one lateral face 50 of the outlet part, this recess 34 opening out Icnitudinally only at the level of one of the ends 36 cf the outlet part, the outlet part having its said one lateral face 50 applied against said lateral panel 6 of the case 2 so as to form with this lateral panel 6 an elongated gas outlet chamber 34 having one closed end 52 and its-other end open 36, said gas outlet part 32 being positioned in such a way that said opening 22 opens out into the gas outlet chamber 34 near to its closed end 52 (figure 4) and that its other open end 36 (figure 3) is situated at the level of said rear panel 4 of the case 2.

The cover 28 has the general shape of a flat plate and is fitted laterally onto said case in a manner parallel to said lateral panel of the case, said outlet part 32 being secured between the cover 28 and the lateral panel 6 of the case 2.

Preferably, as can be seen in figure 3, the general shape of the gas outlet chamber 34 is elongated and curved or with bends 54, 56, while remaining in a plane parallel to the plane of the lateral panel 6 of the case 2 so that the distance covered by the gases along the outlet chamber is increased. This curvature or these bends of the outlet chamber 34 moreover means that the gases which flow along the outlet chamber exit from the outlet chamber according to an outlet direction appreciably perpendicular to the external face of said rear panel 4 of the case 2 (arrow in figure 3).

The outlet chamber 34 has a relatively flattened shape, i.e. the thickness of this chamber measured according to a direction perpendicular to the lateral panel 6 is small (for example 1 to 4 mm) in comparison to the width of the chamber measured according to a direction parallel to the lateral panel 6 (for example 7 to 15 mm) and to its length also measured according to a direction parallel to the lateral panel 6 (for example 30 to 80 mm). This flattened shape ensures efficient cooling of the gases without excessive local overheating of certain parts of .he circuit breaker. This gas outlet chamber 34 is moreover advantageously housed in a part of the circuit breaker which is otherwise unused.

Preferably, the case 2, gas outlet part 32 and cover 28 are made of insulating moulded plastic material.

Claims

1. An electrical circuit breaker comprising a moulded insulating case having a rear panel and two lateral panels extending frontwards from the rear panel, said case housing a main arc extinguishing chamber with deionisation plates producing breaking gases, which electrical circuit breaker further comprises: an opening arranged in one of said lateral panels, opening out into said main chamber; and a gas outlet part of elongated shape, comprising a recess arranged longitudinally in a lateral face of the outlet part, the recess opening out longitudinally only at the level of one of the ends of the outlet part, the outlet part having its said one lateral face applied against said lateral panel of the case in such a way as to constitute with this lateral panel an elongated gas outlet chamber having one closed end and its other end open, said outlet part being positioned in such a way that said opening opens out into the gas outlet chamber near to its closed end and that its other open end is situated at the level of said rear panel of the case.

2. An electrical circuit breaker according to Claim 1, wherein there is provided a cover which has the general shape of the a flat plate and which is mounted laterally on said case in a manner parallel to said lateral panel of the case, said outlet part being secured between the cover and the lateral panel of the case.

3. An electrical circuit breaker according to Claim 1 or 2, wherein said lateral panel of the case comprises on its external face ribs of such a kind that said outlet part is applied against the lateral panel of the case and cooperates with these ribs so that these ribs hold the outlet part in position and contribute to the tightness between the outlet part and the case.

4. An electrical circuit breaker according to any preceding claim, wherein said gas outlet chamber is generally elongated and/or curved in a plane parallel to the plane of the lateral panel of the case so that the distance covered by the gases along the outlet chamber is increased.

5. An electrical circuit breaker according to any preceding claim, wherein said gas outlet chamber is of a shape which is elongated and curved in a plane parallel to the plane of the lateral panel of the case so that the gases which flow along the outlet chamber exit from the outlet chamber in an outlet direction appreciably perpendicular to the external face of said rear panel of the case.

6. An electrical circuit breaker substantially as hereinbefore described with reference to and as shown in Figures 1 to 6.

7. Any novel feature of combination of features disclosed herein.