GB2519807A

GB2519807A - Ventilation Device

Info

Publication number: GB2519807A
Application number: GB1319232.3A
Authority: GB
Inventors: Arend Jan Willem Lammers; Gerhardus Leonardus Nitert
Original assignee: Eaton Industries Netherlands BV
Current assignee: Danfoss Power Solutions II BV
Priority date: 2013-10-31
Filing date: 2013-10-31
Publication date: 2015-05-06
Also published as: GB201319232D0

Abstract

A ventilation device 1 for electrical switchgear comprises a first ventilation member 10 arranged at an end of a ventilation channel and having a plurality of ventilation openings 14 in a first surface 15; a second ventilation member 20 arranged in the ventilation channel and having a second surface 22. In a first state the first surface and the second surface are inclined with respect to each other and space exists between the first surface and the second surface. In a second state the second surface is arranged to be swung against the first surface thereby at least partially closing the plurality of ventilation openings. The swinging of the second surface deforms the second ventilation member such that it bends. The second member may comprise of a plurality of ventilation openings 21 staggered with respect to openings 14 in the first member and when the second member is bent the openings 14 of the first member are completely closed. The device is used with switchgear having arc resistant features.

Description

VENTILATION DEVICE

Technical field

The invention relates to a ventilation device for electrical switchgear, comprising: -a ventilation channel; -a first ventilation member arranged at an end of the ventilation channel and comprising a plurality of ventilation openings in a first surface and; -a second ventilation member arranged in the ventilation channel, the second ventilation member having a second surface.

Background

US6827643 discloses a ventilation opening that is closed in thc event of excess pressure by a ventilation device. The ventilation device has a first member with ventilation openings and a second member with ventilation openings. The first ventilation member and the second ventilation member face each other with a first surface and a second surface respectively. The 2 0 first surface and the second surface are parallel. In the event of excess pressure, the second ventilation member moves linearly in a guiding frame. The second ventilation member has spring-like catch elements with which engaging openings in the guiding frame are associated.

The second ventilation member is fixed when moved against the first ventilation member (i.e. when the ventilation opening is closed) by the spring-like catch elements. The spring-like catch elements are also used for releasable fixing of the second ventilation member when the ventilation opening is open.

The second ventilation member has to be mounted correctly for the releasable fixing to release the second ventilation member in the case of an emergency. When incorrectly mounted, the 3 0 second ventilation member may not release or only release at too high pressures. Both situations reduce the safety shielding that the ventilation device is supposed to provide.

The object of the invention is to provide a reliable ventilation device.

In a first embodiment, the object of the invention is reached by a ventilation device for electrical switchgear, comprising: -a ventilation channel; -a first ventilation member arranged at an end of the ventilation channel and comprising a plurality of ventilation openings in a first surface and; -a second ventilation member arranged in the ventilation channel, the second ventilation member having a second surface, characterized by having a first state wherein the first surface and the second surface are inclined with respect to each other and wherein the ventilation channel forms an open connection and comprises the space between the first surface and the second surface, and the second surface being arranged for being swung against the first surface defining a second state, the second surface at least partially closing the plurality of ventilation openings in the second state.

The skilled person will appreciate that swinging herein refers to an action wherein the relative inclinations of the first and second surface changes. Hence, during the swinging motion, the second surface sways towards the fir st surface. In an embodiment, the second surface is slung 2 0 around a horizontal axis during the swinging motion.

Because in the first state the first surface and second surface arc inclined with each other and the space between them forms part of the open connection formed by the ventilation channel, the plurality of openings forms part of the ventilation channel.

When the second surface is swung against the first surface however, the ventilation openings are at least partially closed. Therefore, the ventilation channel has a smaller area at one end, the first surface being at that end. When the ventilation channel has a smaller area, it is more difficult for gasses to pass the ventilation channel.

The second surface may close the plurality of ventilation openings by more than 50%, 90% or 99%.

According to a second embodiment, thc second surface of thc ventilation device of thc first embodiment is on a swing part of the second ventilation member (20).

According to a third embodiment, the ventilation device according to the second embodiment is provided comprising an immobilisation part arranged to be immobilised with respect to the first ventilation member, the second ventilation member further comprising a connection part connecting the immobilisation part to the swing part, the connection part arranged to be bent such that the second surface swings to the second state.

As the second member comprises an immobilisation part and a connection part that can be bent and connects the immobilisation part and the swing part, the swing part can swing while staying connected to the immobilisation part. Therefore, the orientation of the swing part may change, but the movement of the swing part is still limited in that it remains connected. This prevents that the swing part may get stuck before the second surface reaches the first surface and partially or complctely closes the plurality of openings.

In addition, the second surface will remain in the second state unless the connection part is bent back. Keeping the second surface in the second state is advantageous, as for instance after the occurrence of an arc causing a pressure pushing the swing part against the first ventilation member, the ventilation device limits the flow of toxic gasses through the plurality of ventilation openings. Obviously, when the plurality of ventilation openings is completely closed, the toxic gasses as best prevented from flowing through the channel.

According to a fourth embodiment, a ventilation device according to the second or third embodiment is provided, wherein the swing part is arranged to deform when swung against the first surface such that the shape of the second surface matches the shape of the first surface.

In practise, the first or second surface may deviate a bit from nominal due to production tolerances. As the swing part is arranged to deform when swung against the first surface such 3 0 that it deforms and obtains a shape matching that of the first surface, the second surface can close the plurality of openings in a more predictable way Leakage of gas between the first member and the second member is therefore minimized.

According to a fifth embodiment, a vcntilation dcvicc according to thc second, third or fourth embodiment is provided, arranged for having another end of the ventilation channel being conncctcd to a housing opcning in a housing membcr, wherein the swing part is arranged to abut the housing member in the first state, the second surface comprising a further plurality of ventilation openings arranged to overlap the housing opening in the first state.

As in use. in the first state the swing part abuts the housing member and comprises a further plurality of ventilation openings overlapping the housing opening, a higher pressure in the housing opening than in the plurality ofventilation openings in the first ventilation member results in a relatively high pressure against the swing part pushing against the swing part in the direction of the first surface. This is because where the swing part abuts the housing member, the possibility to equalize the pressure by circumventing the swing part are lowered.

This results in a reliable operation of the ventilation device at least partially closing the plurality of ventilation openings in case of higher pressure in the housing opening than in the plurality of housing openings.

According to a sixth embodiment, a ventilation device according to the fifth embodiment is provided, wherein the swing part comprises a third surface facing away from the second surface 2 0 and comprising the further plurality of ventilation openings, the third surface arranged to abut the housing member and to overlap the housing opening in the first state completely When the third surface overlaps the housing opening completely the complete pressure relive has to go through the further plurality of ventilation openings as long as the third surface abuts the housing member. Therefore the ventilation device can have a relatively high resistance against the swing part being swung against the first ventilation member. This may contribute to a high reliability of the ventilation device to close when needed.

According to a seventh embodiment, a ventilation device according to the fifth or sixth 3 0 embodiment is provided, arranged such that the further plurality ofventilation openings is staggered with respect to the plurality ofventilation openings when the second surface is swung against the fir st surface.

When the further plurality of ventilation openings is staggered with respect to the plurality of ventilation openings, the second surface at least partially closes the plurality ofventilation openings. This is advantageous because the vcntilation dcvicc may bc kept relatively small as opposed to the situation wherein the further plurality of ventilation openings would be arranged in a part of the second surface which would not at least partially close the plurality ventilation openings. That would for instance be the case if the plurality of ventilation openings would be closed by a first part of the second surface and the further plurality of ventilation openings in a second part of the second surface (not overlapping with the first part) and the second part not overlapping the plurality of ventilation openings when the second surface is swung against the first surface.

According to an eighth embodiment, a ventilation device according to any of the preceding embodiments is provided, wherein the second surface closes the plurality ofventilation openings completely in the second state.

When the ventilation openings are completely closed, the largest safety is provided as no gasses can pass the plurality of ventilation openings.

According to a ninth embodiment, a ventilation device according to any of the preceding 2 0 embodiments is provided, wherein the second surface is arranged to be swung against the first surface by a force, the ventilation device arranged for remaining in the second state when the force reduces.

In use the swinging action takes place when the force is higher than a certain threshold value and remains active for some time. As the force causing the second surface to be swung against the first surface is removed, the second surface can return to the first state or remain in the second state. In this embodiment the second surface remains in the second state to keep the further plurality of ventilation openings closed. This may be advantageous to separate toxic gasses from an environment wherein users arc present or to separate gasses that may undesirably react with 3 0 one another.

According to a tenth embodiment, a ventilation device according to any of the preceding embodiments is provided, wherein the second ventilation member (20) is formed from sheet material.

Producing the second ventilation member from sheet material is relatively cheap. In case this embodiment includes the features of the embodiment of claim 3, the sheet material is bent when thc swing part is swung in thc direction of thc first ventilation member. In casc thc shcct material bends non-elastically, the second surface remains against the first surface and the ventilation device does not return automatically to the first state.

In a preferred embodiment, the sheet material can withstand the heat and will not burn when arcs with typical energy occur in low voltage switchgear. In the preferred embodiment, the sheet material may be made from a metal such as galvanized steel.

According to an eleventh embodiment, a ventilation device according to any of the preceding embodiments is provided, wherein the first ventilation member and the second ventilation member are formed from electrically conducting material and wherein the first ventilation member and the second ventilation member are arranged to have an electrically conducting connection with a housing of the electrical switchgear.

When both the first ventilation member and the second ventilation member have an electrical connection with a housing of the electrical switehgear and are both electrically conducting material, they can be used to restrain eleeüical charges from flowing through the ventilation channel. This advantage is maximised when the plurality of ventilation openings is closed completely by the second surface.

The first ventilation member and the second ventilation member may both be made from different electrically conducting materials or from the same electrically conducting materials.

The first ventilation member or the second ventilation member may advantageously be made from a metal such as galvanized steel.

Examples of embodiments the invention will now be described with reference to the 3 0 accompanying schematic drawings. Corresponding reference symbols in the schematic drawings indicate corresponding parts. The schematic drawings are not necessarily to scale and certain features may be exaggerated to better illustrate and explain the present invention. Further, the examples are not intended to be exhaustive or otherwise limit or restrict the invention to the precise configurations shown in the drawings and disclosed in the following detailed description.

Figure 1 depicts an example ofa ventilation device according to the invention in disassembled state Figure 2 depicts the second ventilation member according to the example of the invention Figure 3 depicts a cross section of a ventilation device in assembled state according to the example of the invention

1 0 Detailed description

In a first example of the invention, electrical switchgear for a low voltage system is comprised in a housing (2), i.c. on an intcrior side of thc housing (2). Thc housing is madc from an clectrically conducting material and the housing is connected to ground to protect personal and other persons in thc neighbourhood of thc electrical switchgcar.

In figure 1, a removable housing panel (5) ofthe housing (2) is shown. The housing panel (5) is made from a flat sheet of material such as galvanized steel. The housing panel (5) comprises three housing openings (3), separated by supports (4) which are there to secure the mechanical 2 0 rigidity ofthe housing as the housing openings cannot be made larger to provide a ventilation arca largc cnough without compromising the mechanical rigidity of thc housing.

A ventilation device (1) comprises a first ventilation member (10) and a second ventilation member (20). The first ventilation member (10) and the second ventilation member (20) are placed over thc thrcc housing openings (3) on the exterior sidc of thc housing (2) such that thc first vcntilation mcmbcr (10) is thc outermost part.

The first ventilation member (10) is placed over the second ventilation member (20) whereas the second ventilation member (20) is placed over the three housing openings.

The first ventilation member (10) comprises a plurality of ventilation openings (14) in a rectangular grid (11) having a first (Ill), a second (112), a third (113) and a forth (114) edge as wcll as an cxtcrior side and an interior sidc. The interior side comprises a first surface (15) (fig 3) that comprises the plurality ofventilation openings (14). The ventilation openings (14) are through-holes that extend to the exterior side of the ventilation device (I). In figure 1 the exterior side is shown.

The first ventilation member (10) also comprises a frame (12) of electrically conducting material. The frame (12) comprises a rectangular shaped opening with a first inner edge (121) parallel to the first edge (111). The rectangular shaped opening has a frame opening width, determined by the length of the first inner edge (121), and a frame opening height. The first inner edge (121) is parallel to a fourth inner edge (124). A second inner edge and a third inner edge that is parallel to the second inner edge, correspond to the height of the rectangular frame opening. A frame gasket (6) is placed around the rectangular frame opening facing the housing panel (5) to provide a leak-tight seal. The frame gasket (6) can accommodate a difference in distance equal to the thickness of the second ventilation member (20) and is elecnically conducting.

Between the second edge (112) and the frame (12) there is a triangular shaped sidewall (13).

Similarly between the third edge (113) and the frame (12) there is a triangular shaped sidewall.

Between the forth edge (114) and the frame there is a rectangular shaped sidewall. The first edge (111) is directly at the frame (12). The sidewalls are connected and the grid and sidewalls are connected to the frame (12) such that the first ventilation member (10) is inclined with respect to 2 0 the housing panel (5) and is leak-tight, apart from the ventilation openings. The rectangular grid (11), the frame (12) and the sidewalls of the first ventilation member (10) are formed from electrically conducting metal sheet material such as metals. In this example the rectangular grid (11), the frame (12) and the sidewalls of the first ventilation member (10) are from galvanized steel of 4 or 5 mm thickness. Such sheet material can withstand the heat and will not bum when arcs with typical energy occur in low voltage switchgear.

The plurality ofventilation openings (14) is arranged in 3 rows and 20 columns of rectangular ventilation openings with equal dimensions. The plurality ofventilation openings (14) is placed at the pitch (p) between the columns. Moreover, the smaller dimension of the ventilation openings (14) of the plurality ofventilation openings is in the colunm direction. The pitch (p) is larger than the dimension of the ventilation openings (14) in the column direction. For instance the ratio of the pitch (p) and the dimension of the ventilation openings in the column direction is at least 3 or at least 4 and in this example is 2.2. Between adjacent ventilation openings (14) in the column direction there are separation walls.

The second ventilation member (20) is placed directly over the three housing openings (3). The second ventilation member is formed from a fiat thin sheet of metal, such as galvanized steel of 0.8 or 1 mm thickncss. Such sheet material can withstand the heat and will not bum when arcs with typical energy occur in low voltage switchgear. The second ventilation member (20) comprises a further plurality of ventilation openings (21). Figure 2 shows the second ventilation member. Similar to the plurality of ventilation openings (14), the further plurality of ventilation openings (21) is arranged in 3 rows of rectangular ventilation openings with equal dimension placed at a pitch (p) in a column direction. The larger dimension of the rectangular ventilation openings (21) is in the row direction and the smaller dimension of the rectangular ventilation openings is in the column direction. The pitch (i,) is larger than the dimension of the ventilation openings (21) in the column direction, for instance 3 or 4 times as large. In this advantageous example, the pitch (p) and the dimensions of the ventilation openings (21) of the further plurality ofventilation openings are equal to the pitch (p) and the dimensions of the ventilation openings (14) of the plurality of ventilation openings of the first ventilation member (10). In this example the ratio is 2.2. Between adjacent ventilation openings (21) there arc further separation walls.

The second ventilation member (20) comprises a second surface (22) comprising the further plurality of ventilation openings (21), wherein the second surface faces a first surface of the first ventilation member (10). The second ventilation member (20) further comprises a third surface 2 0 (26) facing away from the second surface (22). The third surface (26) faces the housing panel (5) and covers all three housing openings (3) completely The third surface (26) comprises the further plurality of ventilation openings (21), i.e. the further plurality ofventilation openings (21) overlaps the housing openings (3).

The second surface (22) and the third surface (26) are on a swing part of the second ventilation member (20). In figure 3, the swing part is below the first inner edge (121). The second ventilation member (20) further comprises a connection part (23) and an immobilisation part (24) with a number of through-holes (25) for screws. In figure 3, the connection part (23) is the part from above the inner edge (12) to below the inner edge (12) in between the swing part and the iimnobilisation part. The swing part, the connection part (23) and the immobilisation part (24) are different parts (they don't overlap). In this example, the swing part, the connection part (23) and the inimobilisation part (24) run from the left edge in figure 2 of the second ventilation member (20) to the right edge in figure 2 of the second ventilation member (20).

The positions of the through-holes (25) match the positions of a number of through-holes (125) in the frame. Screws of an electrically conducting material such as steel comprising Nickel are used for attaching the frame (12) and the second ventilation member (20) to the housing panel (5). Hereby the immobilisation part (24) of the second ventilation member (20) is sandwiched between the frame (12) and the housing panel (5) and its position and orientation are fixed (immobilised) with respect to the housing panel (5) and the frame (12). As the second ventilation member (20) is formed from a flat thin sheet of metal and it is sandwiched against the housing panel (5), it is parallel to the housing panel. As the second ventilation member (20) is parallel to the housing panel and the immobilisation part (24)is sandwiched against the housing panel (5), the swing part abuts the housing panel (5). The frame (12) comprises a further plurality of through-holes (126) for further securing the frame (12) to the housing (2).

The flirtherplurality of the ventilation openings (21), the space between the second surface and the first surface and the plurality of ventilation openings (14) forms a ventilation channel. The space between the second surface and the first surface has a triangular cross section corresponding to the triangular shape of two of the side walls of the frame (12). The first surface and the second surface are fiat. As indicated, the first surface is inclined with respect to the housing panel (5) and the second surface is parallel to the housing panel (5), which means that the first surface and the second surface are inclined with respect to each other.

The description above relates to a first state of the ventilation device (1). In use the ventilation device (I) may be mounted in this first state. In this state gasses from the interior of the housing (2), i.e. from the electrical switch gear, may flow through the ventilation channel entering via the further plurality of ventilation openings (21) and exiting via the plurality of ventilation openings (14) or in the opposite direction, i.e. the ventilation channel forms an open connection. Before entering through the further plurality ofventilation openings (21) (or after exiting though the further plurality of ventilation openings (21)) the gasses also flow through the housing openings (3).

When an arc occurs in electrical switchgear in the housing (2), the ventilation device (1) may get into a second state.

The second ventilation member (20) has a width in the column direction that is smaller than the frame opening width. The frame (12) is mechanically much more rigid than the second

II

ventilation member (20). As a consequence, the second ventilation member (20) will bend around the first inner edge of the frame (12) in case of an explosion related to an arc emerging from the electrical switchgear. Thc second ventilation member (20) will bend because such an explosion corresponds to a higher gas pressure against the second ventilation member from the side of the third surface (26) then from the side ofthe second surface (22). The thickness ofthe second ventilation member (20), the material of the second ventilation member and the surface area of the third surface (26) as well as the area of the further plurality ofvcntilation opcnings (21) are chosen such as to bend the connection part (23) at a desired pressure difference or force.

The size and placement of the second ventilation member (20) relative to the first ventilation member (10) are such that the second ventilation member (20) does not reach the fourth inner edge (124). The through-holes (25) in the second ventilation member (20) align the second ventilation member (20) and the frame (12) (and therefore the first ventilation member (10)) such that when the connection part (23) deforms (bends) and the first surface and second surface (22) are pressed against each other, the plurality of ventilation openings (14) is positioned against material of the second ventilation member (20) whereas the second plurality of ventilation openings (21) is positioned against material of the first ventilation member (10).

Because of this staggered configuration, the plurality of ventilation openings (14) is closed completely. This state, wherein the plurality of ventilation openings (14) is closed, is the second state of the ventilation device. In this second state, the further plurality of ventilation openings (21) is closed also. Therefore, the ventilation channel is closed.

In this example, in the second state, the plurality of ventilation openings and the thither plurality of ventilation openings are staggered in the width direction only, not in the height direction. In the width direction they are out of phase by half the pitch (p). As the separation walls are wider than the ventilation openings (21) of the ifirther plurality of ventilation openings, the further plurality of ventilation openings (21) is completely closcd in the second statc and there is even room for some production tolerances. Similarly, in the second state the plurality ofventilation openings (14) is closed completely and there is room for production tolerances because the further separation walls are wider than the ventilation openings (14).

Electrical switchgear is normally provided with a channel to relief the pressure built up after the occurrence of an are and the resulting explosion. After relieving the pressure, i.e. when the corresponding force reduces, the connection part (23) remains bent.

Claims

Claims 1. Ventilation device (1) for electrical switchgear, comprising: -a ventilation channel; -a first ventilation member (10) arranged at an end of the ventilation channel and comprising a plurality of ventilation openings (14) in a first surface (15) and; -a second ventilation member (20) arranged in the ventilation channel, the second ventilation member having a second surface (22), characterized by having a first state wherein the first surface and the second surface are inclined with respect to each other and wherein the ventilation channel forms an open connection and comprises the space between the first surface and the second surface, and the second surface bcing arrangcd for being swung against the first surface defining a second state, the second surface at least partially closing the plurality of ventilation openings (14) in the second state.
2. Ventilation device (1) according to claim 1, wherein the second surface (22) is on a swing part of the second ventilation member (20).
3. Ventilation device (1) according to claim 2, wherein the second ventilation member (20) comprises an immobilisation part (24) arranged to be immobilised with respect to the first ventilation member (10), the second ventilation member further comprising a connection part (23) connecting the immobilisation part to the swing part, the connection part arranged to be bent such that the second surface (22) swings to the second state.
4. Ventilation device (1) according to claim 2 or 3, wherein the swing part is arrangcd to deform when swung against the first surface (15) such that the shape of the second surface (22) matches the shape of the first surface.
5. Ventilation device (1) according to claim 2,3 or 4, arranged for having another end of the ventilation channel being connected to a housing opening (3) in a housing member (5), wherein the swing part is arranged to abut the housing member (5) in the first state, the second surface (22) comprising a further plurality of ventilation openings (21) arranged to overlap the housing opening in the first state.
6. Ventilation device (1) according to claimS, wherein the swing part comprises a third surface (26) facing away from thc sccond surfacc (22) and comprising thc ffirthcr plurality of vcntilation openings (21), the third surface arranged to abut the housing member (5) and to overlap the housing opening (3) in the first state completely.
7. Vcntilation dcvicc (1) according to claim 5 or 6, arrangcd such that thc thrthcr plurality of ventilation openings (21) is staggered with respect to the plurality of ventilation openings (14) whcn thc sccond surfacc (22) is swung against thc first surfacc (15).
8. Ventilation device (1) according to any of the preceding claims, wherein the second surface (22) closes the plurality of ventilation openings (14) completely in the second state.
9. Ventilation device (1) according to any of the preceding claims, wherein the second surface (22) is arrangcd to bc swung against thc first surfacc (15) by a forcc, thc vcntilation dcvicc arranged for remaining in the second state when the force reduces.
10. Vcntilation dcvicc (1) according to any of the prcccding claims, whcrcin thc sccond ventilation member (20) is formed from sheet material.
11. Ventilation dcvicc (I) according to any of the prcccding claims, whcrcin thc first vcntilation mcmbcr (10) and the sccond ventilation membcr (20) arc formed from clcctrically conducting material and wherein the first ventilation member and the second ventilation member are arranged to have an electrically conducting connection with a housing (2,5) of the electrical switch gear.