AU2013100122A4 - Switchboard enclosure - Google Patents

Abstract

A cover for an electric switchboard enclosure includes a top panel having downwardly extending walls that project downward in a direction to define a cavity having an lower opening. A dividing wall crosses the cavity and extends in the downward direction to divide the cavity into 5 (i) a first area for covering the top of an electric switchboard enclosure; and (ii) a second area for exposing a portion of the lower opening to the environment external to the enclosure. The cover also includes a venting means that allows air to pass between the first area and the second area. The second area includes a baffle that is shaped and configured to block a fluid from passing in a straight line of travel from the portion of the lower opening in the second area to the venting 0 means. There is also provided an electrical switchboard, and an enclosure therefor. "NU Lf Figure 1

Description

Regulalor 3.2 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION INNOVATION PATENT Invention Title: Switchboard enclosure The following statement is a full description of this invention, including the best method of performing it known to us: 2 Switchboard Enclosure Field of the invention The present invention relates to switchboards and switchboard enclosures. An aspect of the present invention more specifically relates to top covers of switchboard enclosures. 5 Background of the invention Electric switchboards are used to distribute and control power in an electrical installation. They are comprised of a switchboard enclosure and switchgear, such as circuit breakers, contactors, fuses, busbars, and residual-current devices, housed in the enclosure, and a main switch for switching the input power on and off. The enclosures are typically constructed from 0 panels that form a box, with one of the panels being a hinged door that enables access to the switchgear components held within the box. In a typical configuration, the main switch provides on-off control of electrical current to busbars within the enclosure. Sub-circuit components, eg circuit breakers, are mounted on the busbars to provide selective control over how the current is distributed to circuits fed by the [5 switchboard. Some sub-circuit components must be accessible to an operator, so a protective cover or escutcheon overlays the busbars and other high voltage components to protect the operator from electrocution. There are a number of different types of switchboards, the type being determined by the current rating, use and the point of connection in an electrical network. For example, an 20 electrical installation can include a main switchboard that connects to the electrical network at a supply connection pillar. The main switchboard splits power from the supply to respective main distribution boards. Each main distribution board then further splits the power to a number of distribution boards. The distribution boards then again split the power to supply a number of load centres (eg a house or other accommodation). Thus, there are four different types of 25 switchboards in such an installation. Switchboard enclosures typically include vents to assist in dissipating heat generated within the enclosure by air convection. However, in some environments, such as in the mining industry and other heavy duty industrial applications, the switchboards may be exposed to rain or 3 other sources of water, which could result in a fire if the water enters the enclosure and interacts with the electrical components therein. Some switchboards utilise a vented rain hood, which is a cover that forms the top panel of the enclosure and includes the vents in a partially covered side portion of the cover. While such rain hoods are effective in guarding against water entry from 5 rainfall overhead, they have limited effectiveness in meeting the more rigorous ingress ratings required in these environmentally exposed situations. It is therefore a desired object of the present invention to provide a rain hood or cover for switchboard enclosures with an improved resistance to water entry, or to provide a switchboard or a switchboard enclosure having such a rain hood or cover. 0 Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art. Summary of the invention .5 In one aspect of the present invention, there is provided a cover for an electric switchboard enclosure, the cover including: a top panel having downwardly extending walls that project in a downward direction to define a cavity having a lower opening; a dividing wall crossing the cavity and extending in said downward direction to divide 20 the cavity into (i) a first area for covering the top of an electric switchboard enclosure, and (ii) a second area for exposing a portion of the lower opening to the environment external to the enclosure; and venting means that allows air to pass between the first area and the second area; wherein the second area includes a baffle that is shaped and configured to block a fluid 25 from passing in a straight line of travel from the portion of the lower opening in the second area to the venting means. Preferably, the baffle defines a tortuous path for a fluid to travel between the portion of the lower opening in the second area and the venting means, the tortuous path being a flow path 4 having more than one turn. Preferably the turns include a turn involving a rotation in a first direction and a turn involving a rotation in a second direction, opposite the first direction. Preferably, the baffle has at least one bend along the tortuous path. The baffle may be a single component or may be comprised of a plurality of components. 5 Preferably, the venting means is a plurality of spaced apertures in the dividing wall. The first area may include a second baffle in the form of a bracket that preferably has a plurality of spaced apertures defined therein, the bracket extending in said downward direction from the panel. The bracket is preferably laterally adjacent and offset from the dividing wall, parting the first area into two regions; with a first region that is adjacent to the dividing wall. .0 Advantageously, each aperture of the bracket is vertically offset from each aperture of the dividing wall. In another aspect of the present invention, there is provided a switchboard enclosure having a base, a rear side wall, opposing lateral side walls, a front door and a top cover, wherein the top cover is a cover in accordance with the first aspect, and the venting means is adjacent and 15 above the door, when the door is closed. Preferably, the dividing wall is a strip of rigid material, preferably metal, that has a longitudinal axis. The bracket preferably has a longitudinal axis that is generally parallel to the longitudinal axis of the dividing wall. In one embodiment, a lower end of the dividing wall, that is distal to the panel, bends 20 towards a front wall of the downwardly extending walls. The front wall defines a wall of the portion of the lower opening in the second area. In one embodiment, the baffle is adjacent to and laterally spaced from the dividing wall. Advantageously, the baffle is attached to the dividing wall, preferably at the lower ends of the dividing wall and baffle. 25 Advantageously, the respective apertures in the bracket and in the dividing wall are laterally offset along the length of the walls and may also be vertically offset from each other. Preferably, the baffle is an elongate strip having a generally constant and generally U shaped cross section.

5 In one embodiment, the tortuous path includes an inverted U-shaped trajectory that is firstly towards the panel, then along the panel, and then away from the panel. In an embodiment, the second area is defined such that, when the cover roofs a switchboard enclosure to (a) substantially close the first area at the dividing wall and (b) expose 5 the second area to the external environment, a fluid in the second area of the cavity drains to the external environment. In an embodiment, preferably, the second area and the first region of the first area are configured such that, when the cover roofs a switchboard to (a) substantially close the second region of the first area and (b) expose the first region of the first area to the external 0 environment, a fluid in the second area or the first region of the first area drains to the external environment. Preferably, the cover is shaped such that it complies with requirements for an IP56 water ingress rating, when the first area of the cavity is closed or, at least, when the second region of the first area is closed. The requirements for an IP56 water ingress rating, as referred to herein, 5 are as defined by Australian Standard AS 1939-1990. Advantageously, this protection against water ingress enables safe cleaning by a hose. In a further aspect of the present invention, there is provided a switchboard having switchboard enclosure and switchgear housed therein for distributing and controlling power, the switchboard enclosure including: a base, a rear side wall, opposing lateral side walls, a front door 20 and a top cover, wherein the top cover includes: a venting means above the door, or above and laterally proximal the door, when the door is closed; a hood portion that extends from above the venting means, in a direction away from the rear side, to shelter the venting means from rain, the enclosure having an opening beneath the 25 hood portion through which air that is within the enclosure may exit the enclosure, via the venting means; wherein the hood portion includes a baffle that is shaped and configured to block a fluid from passing in a straight line of travel from the opening to the venting means.

6 Preferably, the venting means is the only means by which fluid may enter the enclosure. The venting means is provided in the top cover, as opposed to lower down in the enclosure, to support convectional air flow through the enclosure. It is appreciated that during manufacture of a switchboard, the switchboard enclosure 5 might not be manufactured as a stand-alone item. The switchboard may be manufactured in a piecemeal manner with the enclosure being assembled as switchgear components are concurrently mounted. In this case, the complete enclosure may only come into existence when the switchboard assembly is completed or near completion. As used herein, the term 'switchboard enclosure' is not intended to exclude switchboard 0 enclosures that have been fully or partially fitted with switchgear to make a functional switchboard. Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings. 5 Brief description of the drawings Figure 1 shows a perspective view of a switchboard enclosure in accordance with an aspect of the present invention; Figure 2 shows a front view of the switchboard enclosure of Figure 1; Figure 3 shows a bottom perspective view of the cover of the switchboard enclosure of 20 Figure 1, the cover being in accordance with an aspect of the present invention; Figure 4 shows an exploded bottom perspective view of the cover of Figure 3; Figure 5 shows a side cross-sectional view of the cover of Figure 3; and Figure 6 shows a side cross-sectional view of a portion of a switchboard enclosure according to an alternative embodiment of the cover in accordance with an aspect of the present 25 invention.

7 Detailed description of the embodiments An embodiment of the present invention is now described in the context of a switchboard enclosure. An exemplary switchboard enclosure 12 is illustrated in Figure 1. The switchboard enclosure 12 has a main body 13 comprised of a metal (eg aluminium, mild steel or stainless 5 steel), and has a base 14 that is closed by a bottom panel 15, opposed side walls 16(ab) rising from the base 14, and a rear side 18 closed by a rear panel 20. A door 22 is pivotably attached by hinges 23 to a rectangular frame 24 that is a flange formed by inward bends 25 in each of the side walls 16 and bottom panel 15, and an upper frame bracket 29 (Figure 2) opposite the inward bend 27 of the bottom panel 15. Along the inside perimeter of door 22 is a sealing gasket (not 0 shown) which creates a seal against rectangular frame 24 when the door 22 is closed. The enclosure has an IP 66 water ingress rating so far as it relates to water ingress via the door. The main body 13 is thus closed on all sides except its top. While the preferred embodiment of the enclosure 12 includes its base 14 closed by a bottom panel 15, it is appreciated that in other embodiments the base 14 may be open provided .5 that, in use, the base 14 seals against a floor surface when installed. The door 22 has two handles 26, each of which may be independently turned about an axis that is perpendicular to the plane of the door to actuate the handle between a locked and unlocked position. In the unlocked position (shown in Figures 1 and 2), the handle faces downwards. A latch (not shown) on the opposite side of the door is fixed to the pivot shaft (not 20 shown) of the handle that passes through the door. The latch projects in the same direction as the handle so as to be point downward from the pivot shaft when the handle is in the unlocked position. By rotating the handle by 90 degrees in a counter-clockwise manner, the latch points toward side panel 16a with a distal end of the latch held frame 24 behind a side panel 16a to lock the door closed. Side wall 16b has hinges. (not shown) on the inside surface of the wall, which 25 pivotably mount escutcheon (not shown), so that the escutcheon can open through the door frame 24. The escutcheon is thus marginally smaller that the door frame 24. When the escutcheon is in its closed position, it abuts escutcheon landing bracket 33 which extends inwardly and then downwardly from the upper frame bracket 29. The rear panel 20 of the enclosure includes two cable gland plates: a top cable gland plate 30 19 (Figure 6) and a lower cable gland plate (not shown) in the top and bottom halves of the rear panel 20. Pre-punched rail mounting system 21 is welded to the rear panel 20, and runs along the 8 length of the rear panel 20 to provide flexibility in mounting internal panels and to the rear panel 20. The enclosure 12 is closed, at its top, by cover 30 which is seated onto an open rectangular seat 32 (Figure 6) of the main body 13. The open rectangular seat 32 is. defined at the 5 respective top ends of the side panels 16a, 16b, upper frame bracket 29 and rear panel 20. The cover 30 has a shell housing 34 formed from a sheet of stainless steel or aluminium that is bent downwardly on each side, by 90 degrees, to create four downward extending walls 36(a, b), 37, 38 projecting from a flat panel 39 in a downward direction. A bottom perspective view of the cover 30, in isolation from the main body 13 of the switchboard enclosure 12, is illustrated as an 0 assembly in Figure 3 and in an exploded view in Figure 4. The walls 36, 37, 38 terminate at respective free-ended lower edges 42, 44, 46 so as to define a cavity 40 therebetween, which is roofed by flat panel 39 and has a lower opening that opens downwardly, away from the flat panel 39. The front wall 37 of the shell is shorter than the side walls 36 and rear wall 38 of the shell (best shown in Figure 4) so that the front wall's lower edge 44 is higher than the other lower 5 edges 42, 46 when the cover 30 covers the enclosure 12. The lower edges 42, 44, 46 of the walls 36, 37, 38 are parallel to the panel 39, except for a slanted edge portion 48 between each lower edge 42 of the respective side walls 36. The slanted edge portion 48 is situated towards the front of the cover between a parallel front length 50 and the main parallel length 52 of the lower edge 42. The slanted portion 48 tapers the height of the side wall 36 to a shorter height so that the .0 front end 54 of the side wall's lower edge 42 aligns with the lower edge 44 of the front wall 37. The front end 56 and rear end 58 of each side walls 36 is sealingly welded to the front wall 37 and rear wall 38, respectively. When the cover is oriented with the cavity 40 opening downwardly, fluid on one side of a wall 36, 37, 38, outside the cavity 40, must pass beneath the wall to enter the cavity. 25 The cover 30 includes a divider 60, formed from a bent elongate sheet of metal. The divider 60 crosses the panel 39 by extending longitudinally the entire length from the one side wall 36a to the opposite side wall 36b of the shell housing 34. The divider 60 has an upper wall 62 that is welded, flush against the inside surface of panel 39. The upper wall 62 bends by approximately 90 degrees to form a dividing wall 64. From the bottom end of the dividing wall 30 64, a deflector portion 68 depending from the dividing wall 64 then bends forwardly, with a slight downward draft of about 10 degrees. Venting means 66 is incorporated into the dividing 9 wall 64, in the form of a number of apertures 70 that are spaced at even intervals along the length of the dividing wall 64. As can be seen in Figure 5, which illustrates a cross-sectional side view of the cover 30, the dividing wall 64 divides the cavity 40 into a first area 72, rearward from the dividing wall 64, 5 and a second area 74, forward of the dividing wall 64. The sectional plane of the cross sectional side view of Figure 5 is between adjacent apertures 70, so the apertures 70 are not visible in this view. The first area 72 of the cavity 40 includes a filter assembly 76 fixed against the top panel 39 by welding the shell 34 of the cover 30 to a front bracket 78 and to an opposed rear bracket 80 0 of the filter assembly 76. Spanning between the front and rear brackets 78, 80 on either side of the brackets 78, 80 are side brackets 82, 84. Each of the brackets 78, 80, 82, 84 has respective bottom lips 86, 88, 90, 92 which point towards the respective opposing brackets so as to collectively define an inwardly flanged rectangular frame 93. Embedded in each of the lips 90, 92 of the side brackets 82, 84 are respective pairs of blind nuts 94, 96. When the cover 30 is 5 fitted to the rest of the enclosure 12, the cover 30 rests on the open rectangular seat 32 (Figure 6) of the enclosure 12, with the front and rear brackets sitting flush against the seat 32. The cover 30 is secured in place by fasteners 35 which pass through the rectangular seat 32 into the blind. nuts 94, 96. When seated in this manner, the lower edges 42, 46 of the shell's side and rear walls 36, 38 form a skirt 97 that downwardly overhangs the enclosure 12 from the seat 32. 20 The front bracket 78 includes a plurality of apertures 99 interspaced between (ie. laterally offset), and offset slightly above (ie. vertically offset), the apertures 70 of the dividing wall 64. However, for improved illustration, Figure 6 shows an embodiment in which the apertures 70 and 99 are laterally aligned with respect to the longitudinal axis the dividing wall 64. Thus, in Figure 6, the apertures 70 are offset from the apertures 90, but the offset is in this case only in 25 the vertical direction. The front bracket 78 is adjacent and offset from the dividing wall 64, parting the first area 72 of the cavity 40 into a first region 100 defined by the space between the front bracket 78 and the dividing wall 64, and a second region 102 being the remainder of the cavity 40, ie the region of the cavity to the opposite side of the bracket 78. Air in the second region 102 can pass to the 30 first region 100 via the apertures 99 in the bracket 78, as illustrated by the arrows in Figure 6.

10 The second area 74 is defined by the front portion 41 of the shell 34, being the portion that extends from above the apertures 70 in the dividing wall 64, in a direction away from the rear wall 38 of the cover or rear side 18 of the enclosure 12. The hood portion includes the front wall 37 of the shell 34, which is configured to overhang the apertures 70 such that the lower edge 5 44 of the front wall is below apertures 70. The hood 41 acts to shelter the venting means 70 from rain. The second area 74 of the cavity 40 includes a baffle 104 having a longitudinal axis parallel to the longitudinal axis of the dividing wall 64. The baffle 104 includes a first flat wall 106 that is vertically oriented to be parallel to and spaced from the dividing wall 64. The baffle 0 104 also includes a bottom flat wall 108 that extends forwardly from the bottom of the first flat wall 106, at an obtuse angle to be parallel with deflector portion 68 of the dividing wall 64. Accordingly, the flat wall 108 has a slightly downward draft as it extends away from the first flat wall 106 of the baffle 104. The slightly downward draft reduces the accumulation of dust and dirt on the baffle 104. The flat wall 108 also extends sufficiently far to cover the door 22 of the 5 enclosure 12 and thereby minimise build up of dust or dirt on the top edge of the door 22. The first flat wall 106 has a height that is marginally less than the height of the dividing wall 64, such that an horizontal air gap channel 111 is provided between the top end 110 of the first flat wall 106 and the top panel 39 of the cover 30, and more specifically, between the first flat wall 106 and the upper wall 62 of the divider 60. An upper wall 112 extends forwardly at 90 20 degrees from the first wall 106 of the baffle 104. The forward length of the upper wall 112 is more than half of the distance between the dividing wall 64 and the front wall 37 of the cover 30, with the distal end 114 of the upper wall 112 stopping just short of the front wall 37. The longitudinal length of the baffle 104 is substantially the same as, but marginally less, than the longitudinal length of the divider 60. The length of the baffle spans to cover all 25 apertures 70 of the divider 60 so that the baffle creates an inverted U-shaped tortuous path for fluid to travel between a front portion 120 of the lower opening of the second area and the apertures 70 of the divider 60. The U-shaped tortuous path is defined by the horizontal channel 111 and lateral vertical channels 113(a,b) extending down from the horizontal channel 11. The tortuous path 111, 1 13(a,b) runs from a front portion 120 of the lower opening of second area 74, 30 open to the environment, to the apertures 70 in the dividing wall 64. In this embodiment, the tortuous path 111, 113(a,b) further includes a further bend 119 to pass horizontally through the 11 apertures 70. Fluid must generally travel along the tortuous path to transit between the front opening 120 to any of the apertures 70 to enter the enclosure 12. The tortuous path includes a 90 degree rotation in a first direction (clockwise in figure 6) at the top end of vertical channel l 13a, to enter the channel 111 at the front end 114 of the baffle 104. Then, at the top end 110 of the 5 first flat wall 106 of the baffle 104, the tortuous path includes another 90 degree rotation in the same direction to leave the channel 111 and enter the other vertical channel 113(b). Finally, the tortuous path includes another turn 119 in the opposite direction (anticlockwise in figure 6) to pass through an aperture 70 in the dividing wall 64. The longitudinal length of the baffle 104 is slightly less than that of the divider 60, so as to leave a small gap (not shown) either side of the 0 baffle 104, between the baffle and respective side walls 36a, 36b of the cover 30. The small gap allows any fluid that may accumulate between the baffle 104 and divider 60 to drain along the ends of the deflector portion 68 of the divider 60, adjacent side walls 36a, 36b of the cover 30. Referring to Figure 6, the filter assembly frame 93 holds a rectangular air filter 98 which fills the filter assembly 76. The filter 98 is comprised of a non-hygroscopic mesh membrane, .5 which provides an anti-condensation barrier to capture dust that enters the enclosure 12 from the outside environment, allowing the enclosure to ventilate, whilst also preventing water from condensing and falling onto equipment in the enclosure 12. Figure 6 illustrates the path flow 122 that air must take to leave the enclosure 12. The air must rise up the inside of the enclosure 12 to enter the second region 102 of the first area 72 of 20 the cavity 40. The air must then pass through the filter 98 and through apertures 99 in the bracket 78 into the first region 100 of the first area 72. The air must then cross the first region 100 by travelling down (in the embodiment of Figure 6) or down and across (in the embodiment of Figure 5) to any of the apertures 70 in the divider wall 64, passing through a divider wall's apertures 70 to enter the second area 74 of the cavity 40. Once in the second area 74, the air must 25 traverse along the tortuous path 113(ab), 11l by turning upwards and moving along vertical channel 113(b) towards the panel 39, then parallel to the panel 39 via channel 111, towards the front wall 37 of the cover. Once the air passes the front end 114 of the baffle 104, the air must travel down again via vertical channel 113(a) to exit the second area 74 via the opening 120. The path between the opening 120 and the apertures 70 of the divider 60 prevents, by 30 blocking, fluid from travelling in a straight line, thereby making it difficult for a jet of fluid to pass from the opening 120 into the first area 72 of the cavity 40.

12 It is not impossible for fluid to travel into the first area 72. However, to enter the main part of the enclosure 12, the fluid would need to travel the tortuous path 11, 1 13(a,b), 119 to pass through the apertures 70 and then further redirection to pass through the apertures 99 in the bracket 78. Therefore, more likely, any fluid that reaches the first region 100 of the first area 72 5 would be drained out of the enclosure 12 via a small gap 115 between the divider wall 64 and the upper bracket 29 of the door frame 24. The gap is sufficiently small to allow draining without adding significant risk of water entering the cavity 40 from the external environment 130 via that gap, especially because there is no straight line of travel between the outside environment and the apertures 99 of the bracket 78. In one embodiment of the invention the tortuous path for 0 water to enter the enclosure provides the enclosure with an IP 56 water ingress rating. Therefore, in this embodiment, for water to enter the enclosure 12, it generally must pass at least a primary barrier and secondary barrier. The primary barrier formed by baffle 104 combined with divider 60, while the secondary barrier is formed by front bracket 78. Each barrier is configured to reflect any incident water away from the first area 72 of cavity 40, which 5 is in fluidic communication with the inside of the enclosure. It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Claims (5)

1. A cover for an electric switchboard enclosure, the cover including: a top panel having downwardly extending walls that project in a downward direction to define a cavity having a lower opening; 5 a dividing wall crossing the cavity and extending in said direction downward to divide the cavity into (i) a first area for covering the top of an electric switchboard enclosure, and (ii) a second area for exposing a portion of the lower opening to the environment external to the enclosure; and venting means that allows air to pass between the first area and the second area; 0 wherein the second area includes a baffle that is shaped and configured to block a fluid from passing in a straight line of travel from the portion of the lower opening in the second area to the venting means.

2. A cover in accordance with claim 1, wherein the baffle defines a tortuous path for a fluid to travel between the portion of the lower opening in the second area and the venting 5 means, the tortuous path being a flow path having more than one turn.

3. A cover in accordance with claim 1 or 2, wherein the venting means is a plurality of apertures in the dividing wall, and the first area includes a bracket that has apertures defined therein, the bracket extending from the panel in said downward direction and along a longitudinal axis that is generally parallel to a longitudinal axis of the dividing wall, the bracket 20 parting the first area into two regions, wherein each aperture of the bracket is offset from each aperture of the dividing wall.

4. A switchboard enclosure having a base, a rear side wall, opposing lateral side walls, a front door and a top cover, wherein the top cover is a cover in accordance with any one of the preceding claims, and the venting means is adjacent and above the door, when then the door is 25 closed.

5. A switchboard having a switchboard enclosure and switchgear housed therein for distributing and controlling power, the switchboard enclosure including: 14 a base, a rear side wall, opposing lateral side walls, a front door and a top cover, wherein the top cover includes: a venting means above the door, or above and laterally proximal to door, when the door is closed; 5 a hood portion that extends from above the venting means, in a direction away from the rear side, to shelter the venting means from rain, the enclosure having an opening beneath the hood portion through which air that is within the enclosure may exit the enclosure, via the venting means; wherein the hood portion includes a baffle that is shaped and configured to block 0 a fluid from passing in a straight line of travel from the opening to the venting means.