GB2606543A

GB2606543A - Switchgear

Info

Publication number: GB2606543A
Application number: GB2106740.0A
Authority: GB
Inventors: Ertl Michael; Spritzendorfer Bernd
Original assignee: Eaton Intelligent Power Ltd
Current assignee: Eaton Intelligent Power Ltd
Priority date: 2021-05-12
Filing date: 2021-05-12
Publication date: 2022-11-16
Also published as: WO2022238008A1

Abstract

An electrical switchgear 1 such as a miniature circuit breaker or residual current circuit breaker, comprises a housing 2 having first and second contacts forming an electrical conduction path, a gas discharge opening, and an arc extinguishing chamber 3 having a plurality of arc extinguishing plates 4 mounted therein. The arc extinguishing chamber has at least one gas inlet 5 for gases accelerated by an electric arc caused during disconnection of the contacts, at least one gas outlet 6 connected to the discharge opening to discharge gases from the chamber, and a pre-chamber area 7 extending from the contacts to the gas inlet. The arc extinguishing chamber also comprises at least one bypass outlet 8 located on its side with respect to a longitudinal direction of the plates, and a plurality of flow channels 9 directly connects the bypass outlet with the gas inlet of the pre-chamber area to recirculate at least some of the gases accelerated by the arc back to the pre-chamber area. The redirection of exhaust gases back to the pre-chamber and behind the electric arc helps prevent an arc from returning from the extinguishing chamber. One bypass outlet may be provided for each arc plate.

Description

Switchgear The present disclosure relates to a Switchgear according to the generic part of claim 1.

It is known, that separating electrical contacts carrying an electric current causes an electric arc between the contacts. Switchgears, especially circuit breakers, which are intended to interrupt high currents typically comprise an arc extinguishing chamber for extinguishing said electric arc.

Conventionally, the arc extinguishing chamber comprises a plurality of arc extinguishing grid-plates which are spaced and particularly isolated from each other. The arc is split and cooled at the arc extinguishing grid-plates and thus extinguished. The arc extinguishing grid-plates are hold in an insulated body. The arc extinguishing chamber usually has a gas outlet which is connected to a gas discharge opening of the switchgear to discharge gases, which have been accelerated and heated by said electric arc from the arc extinguishing chamber and hence from the switchgear.

The aforementioned switchgear has the disadvantage, that the pressure reduction inside the arc extinguishing chamber is inhomogeneous and the short-circuit capacity is rather low. Therefore, parts of the switchgear, particularly in case of flashbacks, might be damaged.

it is an object of the present invention to overcome the drawbacks of the state of the art by providing a switchgear with which an improved short-circuit capacity, respectively the switch-off behaviour and a reduced probability of flashbacks is achieved.

According to the invention, the aforementioned object is solved by the features of claim 1.

As a result, the switchgear fulfils the object and has the advantages, that the probability of flashbacks is reduced and an improved short-circuit capacity, respectively a better switch-off behaviour is achieved. The arc extinguishing chamber has at least one bypass-outlet located sideways to a longitudinal extension of the arc extinguishing grid -plates, whereby, in order to increase the backflow of said gases, a plurality of flow channels directly connects the at least one bypass-outlet of the arc extinguishing chamber with at least one gas inlet of the pre chamber area to lead at least a part of said accelerated gases back to the pre chamber area and hence, back to the bypass-outlet. Thus, said gases are conducted symmetrically out of intermediate chambers of the arc extinguishing chamber to ensure a more homogeneous pressure reduction and to prevent a moving back of the arc out of the extinguishing chamber. The direct connection of the flow channels with the arc extinguishing chamber leads to an additional pressure increase behind the arc extinguishing grid-plates leading to a reduction of the gas pressure in the arc extinguishing chamber. Because of the reduction of the dynamic pressure via the flow channels in the area of the arc extinguishing chamber which counteracts the electric arc, an undisturbed entry of the electric arc into the arc extinguishing chamber is abetted. The redirected gases, which are introduced behind the electric arc accelerate said arc in the direction of the arc extinguishing chamber. Thus, the probability of flashbacks is reduced and the electric arc run is accelerated.

The dependent claims describe further preferred embodiments of the invention.

The invention is described with reference to the drawings. The drawings only illustrate exemplary embodiments of the invention, Fig, 1 illustrates a preferred embodiment of a section of the switchgear comprising an arc extinguishing chamber in a sectional view; Fig, 2 illustrates a preferred embodiment of the arc extinguishing chamber in an axonometric projection; Fig. 3 illustrates the preferred embodiment of the arc extinguishing chamber in another axonometric projection; Fig, 4 illustrates the preferred embodiment of the arc extinguishing chamber in a side view; Fig, 5 illustrates the preferred embodiment. of the arc extinguishing chamber in a back view; Fig. 6 illustrates the preferred embodiment of the arc extinguishing chamber in another sideview.

Fig. 1 to 6 illustrate at [east a part of a preferred embodiment of a Switchgear 1, comprising a housing 2 having a gas discharge opening, at least one first contact and at least one second contact to form an electrical conducting path through the switchgear 1, an arc extinguishing chamber 3 with a plurality of arc extinguishing grid-plates 4 mounted in said arc extinguishing chamber 3, whereby the arc extinguishing chamber 3 has at least one gas inlet 5 for gases accelerated by an electric arc caused by disconnecting the at least one first contact and the at least one second contact from each other, and at least one gas outlet 6 connected to said gas discharge opening to discharge said gases from the arc extinguishing chamber 3, and a pre chamber area 7 extending from the contacts to the at least one gas inlet 5 of the arc extinguishing chamber 3, whereby the arc extinguishing chamber 3 has at least one bypass-outlet 8 located sideways to a longitudinal extension of the arc extinguishing grid-plates 4, whereby a plurality of flow channels 9 directly connects the at least one bypass-outlet 8 of the arc extinguishing chamber 3 with at least one gas inlet 5 of the pre chamber area 7 to lead at least a part of said accelerated gases back to the pre chamber area 7.

As a result, the switchgear 1 fulfils the object and has the advantages, that the probability of flashbacks is reduced and an improved short-circuit capacity, respectively a better switch-off behaviour is achieved. The arc extinguishing chamber 3 has at least one bypass-outtet 3 located sideways to a longitudinal extension of the arc extinguishing grid-plates 4, whereby, in order to increase the backflovv of said gases, a plurality of flow channels 9 directly connects the at least one bypass-outlet 8 of the arc extinguishing chamber 3 with at least one gas inlet 5 of the pre chamber area 7 to lead at least a part of said accelerated gases back to the pre chamber area 7 and hence, back to the bypass-outlet 8. Thus, said gases are conducted symmetrically out of intermediate chambers of the arc extinguishing chamber 3 to ensure a more homogeneous pressure reduction and to prevent a moving back of the arc out of the extinguishing chamber 3. The direct connection of the flow channels 9 with the arc extinguishing chamber 3 leads to an additional pressure increase behind are arc extinguishing grid-plates 4 Leading to a reduction of the gas pressure in the arc extinguishing chamber 3. Because of the reduction of the dynamic pressure via the flow channels 9 in the area of the arc extinguishing chamber 3 which counteracts the electric arc, an undisturbed entry of the electric arc into the arc extinguishing chamber 3 is abetted. The redirected gases, which are introduced behind the electric arc accelerate said arc in the direction of the arc extinguishing chamber 3. Thus, the probability of flashbacks is reduced and the electric arc run is accelerated.

The switchgear 1 is particularly embodied as a circuit breaker, preferably a miniature circuit breaker (MCB), a residual current operated circuit breaker (RCB0), or an arc fault detection device (AFDD).

The switchgear comprises a housing 2 with a gas discharge opening to discharge gases, which have been accelerated by said electric arc. The switchgear 1 further comprises at least one first contact and at least one second contact to form an electrical conducting path through the switchgear 1. Preferably, one of the contacts is a movable contact and the other contact is a stationary contact.

Further, the switchgear comprises the arc extinguishing chamber 3 with a plurality of arc extinguishing grid-plates 4 mounted in said arc extinguishing chamber 3. The arc extinguishing grid-plates 4 are preferably spaced from each other, which is exemplarity shown in Figs 2, 3, 4 and 6.

Typical other terms for the arc extinguishing chamber 3 are arc quenching device, arc extinguishing device or arc quenching chamber.

The arc extinguishing chamber 3 has at least one gas inlet 5 for hot gases that have been accelerated by said electric arc caused by disconnecting the at least one first contact and the at least one second contact from each other, and at least one gas outlet 6 connected to said gas discharge opening to discharge said gases from the arc extinguishing chamber 3, Preferably, the arc extinguishing chamber 3 is embodied as a chamber with a housing, comprising at least two sidewalk, whereby each sidewall is connected to a backwall, The bypass-outlets Bare preferably located at each sidevvall, which can be exemplarity seen in Figs, 2 and 3 and 4 and 6.

It can be preferred, that the housing of the arc extinguishing chamber 3 is manufactured in one piece. It might also be preferred, that the housing of the arc extinguishing chamber 3 is made of plastic.

The arc extinguishing chamber 3 has a plurality of mounting recesses or mounting holes 10 in order to mount the arc extinguishing grid-plates 4, which can be exemplarily seen in Figs. 2, 3, 4 and 6. In case of mounting holes 10, each arc extinguishing grid-plate 4 preferably has at least one extension sideways to its longitudinal extension to engage in a mounting hole 10 of the arc extinguishing chamber 3.

In a mounted state, the arc extinguishing grid-plates 4 are preferably arranged parallel to each other.

Preferably, the arc extinguishing chamber 3 has a plurality of gas outlets 6 at its backwall, which is exemplarily shown in Figs 2, 3 and 5.

The switchgear 1 further comprises a pre chamber area 7. The pre chamber area 7 is particularly an open space extending from the contacts to the at least one gas inlet 5 of the arc extinguishing chamber 3.

As noted before, the arc extinguishing chamber 3 has at least one bypass-outlet 8 located sideways to a longitudinal extension of the arc extinguishing grid-plates 4. A plurality of flow channels 9 directly connects the at least one bypass-outlet 8 of the arc extinguishing chamber 3 with at least one gas inlet 5 of the pre chamber area 7 to lead at least a part of said accelerated gases back to the pre chamber area 7. A part of the accelerated gases is basically lead in a circle.

Preferably, the at least one bypass-outlet 8 is arranged sideways to the gas inlet 5 and the gas outlet 6 of the arc extinguishing chamber 3, which is exemplarily shown in Fig. 1.

According to a preferred embodiment, at. least a part of the plurality of flow channels 9 is located between the housing 2 and the pre chamber area 7.

Preferably, at least a part of the plurality of flow channels 9 is located between the housing 2 and the arc extinguishing chamber 3.

Preferably, the plurality of flow channels 9 is located at both sides of he pre chamber area 7.

According to another preferred embodiment, the arc extinguishing chamber 3 has at least two bypass-outlets 8 located opposite to each other, whereby the bypass-outlets 8 are each connected to at least one flow channel 9. Thus, said accelerated gases can be led back to the pre chamber area 7 in a very efficient way.

According to another preferred embodiment, the arc extinguishing chamber 3 has a plurality of bypass-outlets 8 being spaced to each other, which is exemplarily shown in Figs 2 to 6.

According to another preferred embodiment, the arc extinguishing chamber has at least one bypass-outlet 3 per arc extinguishing grid-plate 4.

According to another preferred embodiment, the plurality of flow channels 9 is designed as grooves in the housing of the switilip,ear 1. Thus, the flow channels 9 can be built in an easy way.

Preferably, the grooves are arranged parallel to a longitudinal extension of the housing.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims. The exemplary embodiments should be considered as descriptive only and not for purposes of limitation. Therefore, the scope of the present invention is not defined by the detailed description but by the appended Hereinafter are principles understanding and interpreting the actual disclosu Features are usually introduced with an indefinite article "one, a, an". Unless otherwise stated in the context, therefore, "one, a, an" is not to be understood as a numeral.

The conjunction "or" has to be interpreted as inclusive and not as exclusive, unless the context dictates otherwise. "A or B" also includes "A and B", where "A" and "B" represent random features.

By means of an ordering number word, for example "first", "second" or "third, in particular a feature X or an object Y is distinguished in several embodiments, unless otherwise defined by the disclosure of the invention. In particular, a feature X or object V with an ordering number word in a claim does not mean that an embodiment of the invention covered by this claim must have a further feature X or another object Y.

Claims

CLAIMS1. Switchgear (1), comprising a housing (2) haying a gas discharge opening, at least one first contact and at least one second contact to form an electrical conducting path through the switchgear (1), an arc extinguishing chamber (3) with a plurality of arc extinguishing grid-plates (4) mounted in said arc extinguishing chamber (3), whereby the arc extinguishing chamber (3) has at least one gas inlet (5) for gases accelerated by an electric arc caused by disconnecting the at least one first contact and the at least one second contact from each other, and at least one gas outlet (6) connected to said gas discharge opening to discharge said gases from the arc extinguishing chamber (3), and a pre chamber area (7) extending from the contacts to the at least one gas inlet (5) of the arc extinguishing chamber (3), characterised in, that the arc extinguishing chamber (3) has at least one bypass-outlet (8) located sideways to a longitudinal extension of the arc extinguishing grid-plates (4), whereby a plurality of flow channels (9) directly connects the at least one bypass-outlet (8) of the arc extinguishing chamber (3) with at least one gas inlet (5) of the pre chamber area (7) to lead at least a part of said accelerated gases back to the pre chamber area (7).
2. Switchgear (1) according to claim 1, characterised in, that at least a part of the plurality of flow channels (9) is located between the housing (2) and the pre chamber area (7).
3. Switchgear (1) according to claim 1, characterised in, that least a part of the plurality of flow channels (9) is located between the housing (2) and the arc extinguishing chamber (3).
4. Switchgear (1) according to claim 1 or 2, characterised in, that the arc extinguishing chamber (3) has at least two bypass-outlets (8) located opposite to each other, whereby the bypass-outlets (8) are each connected to at least one flow channel (9).
5. Switchgear (1) according to one of the claims 1 to 3, characterised in, that the arc extinguishing chamber (3) has a plurality of bypass-outlets (8) being spaced to each other.
6. Switchgear (1) according to one of the claims 1 to 4, characterised in, that the arc extinguishing chamber (3) has at least one bypass-outlet (8) per arc extinguishing grid-plate (4).
7. Switchgear (1) according to one of the claims 1 to 6, characterised in, that the plurality of flow channels (9) is designed as grooves in the housing of the switchgear (1)._