GB2508372A

GB2508372A - Housing for low voltage system with cooling airflow

Info

Publication number: GB2508372A
Application number: GB201221492A
Authority: GB
Inventors: Tim Lie; Carmen Man
Original assignee: Eaton Industries Netherlands BV
Current assignee: Danfoss Power Solutions II BV
Priority date: 2012-11-29
Filing date: 2012-11-29
Publication date: 2014-06-04
Also published as: WO2014083077A1

Abstract

The invention relates to a housing for a low voltage system, which housing comprises: a frame 5 for housing a number of electrical devices, such as switchgear, arranged in slots of the frame, wherein the frame has at least a bottom wall, two vertical side walls and a top wall; a channel having an air inlet 16 near the bottom of the frame and an air outlet 17 near the top of the frame; wherein the channel is in heat exchanging contact with the frame. In some embodiments the electrical devices have ribs which reside within the airflow.

Description

Natural ventilation system inside a low voltage system The invention relates to a housing for a low voltage system, which housing comprises: -a frame for housing a number of electrical devices, such as switchgear, arranged in slots of the frame, which frame has at least a bottom wall, two vertical side walls and a top wall.

Such a housing is used to house several electronic devices like switches, metering devices and distribution components. These electronic devices are for example used to switch pumps and electric motors.

The housing, which is also called a cabinet, is provided with busbars to supply power and with outgoing busbars to conduct switched power to a device, like a motor or a pump. A frame with slots in which the electronic devices can be placed is furthermore provided in the housing. The electronic devices can easily be drawn-out the slot of the frame for testing of the electronic device or for replacement.

These kind of housings have to comply to certain requirements with regard to ingress protection. For example, ingress of dust can cause malfunction of the switches or accidental arcing. In more harsh environments, it could also be a requirement, that no moist or water can penetrate the housing. These requirements are summarized in a standard and is expressed by a so called IP-rating.

To obtain a certain IP-rating with a housing according to the preamble it is common to make the housing air-tight. This is achieved by a closed housing and electronic components having a front panel, which can seal airtight in a slot of the frame.

However, the electronic devices generate heat, while they conduct typically high power. To ensure that a housing does not get overheated, the number of electronic components is limited in view of the size of the housing. The heat of these electronic components needs to diffuse through the housing to the walls of the housing, such that the heat can be radiated into the ambient air. Providing venting openings in the housing would reduce the IP rating and is therefor undesired.

So, with the known housings, there is a limit to the number of electronic devices in a housing or a limit to the reduction of size of the housing in view of the number of electronic devices.

It is accordingly an object of the invention to reduce the above mentioned disadvantages.

This objcct is achieved with a housing according to the preamble, which housing is characterized by a channel having an air inlet near the bottom of the frame and an air outlet near the top of the frame, wherein the channel is in heat exchanging contact with the frame.

The channel provides a chinmey in which a natural draft can occur with the heat of the electrornc components. Due to the air inlet being positioned near the bottom and the air outlet being positioned near the top, the heated air can rise and a natural draft can be generated.

This ensures that hcat from the clectronic componcnts is transported relativc quickly from the heat source away. Thc hcat of the clcctronic components can bc transferrcd by radiation and/or by direct contact to the air in the channel.

In an embodiment of the housing according to the invention a wall of the channel is one of the yertical side walls of the frame. In this embodiment a regular frame can be easily converted to a frame for the invention having a channel arranged to one side of the framc, which channel is used to transport heat away from the electronic components.

In a preferred embodiment of the housing according to the invention the channel is arranged on both sides of the frame. By ananging the channel on both sides of the frame, such that the channel has two sections, each section running on a side of the frame, the heat can be exchanged morc quickly and transferred quicker.

In yet another preferred embodiment of the housing according to the invention, the air inlet and the air outlet of the channel are arranged in an outer wall of the housing.

With this cmbodimdllt, thc channcl can draw in ambient air through the air inlet, cxchange heat between the ambient air and the electronic components and then expel the heated ambient air via the air outlet.

Bccause both the air inlet and the air outlet are arranged in the housing, the housing can be air tight, while sufficient ambient air can flow through the channel. As there is only a heat exchange connection between the channel and the frame, air, dust, moist and the like in the channel cannot penetrate the housing, such that the IP rating is maintained.

In another embodiment of the housing according to the invention ribs are arranged in the channel in heat exchanging contact with the frame. By providing ribs in thc channel, the heat exchanging surface of the channel is enlarged, such that the heat exchanging capacity is increased.

The invention also relates to a combination of a housing according to the invention and at least one electrical device, such as switchgear, wherein the at least one electrical device has at least one heat exchanging surface in contact with the channel. This contact can be by a fixed attachment of the electrical device to the frame in the housing or by having a sliding contact, such that the electrical device can be pulled out from the frame, when necessary.

In a preferred embodiment of the combination according to the invention the at least one heat exchanging surface of the electrical device is in contact with part of the frame.

Typically, the electrical devices are slit into a slot of the frame. When the electrical device is designed such that it has a heat exchanging surface, it can be ensured, that this heat exchanging surface will be in contact with the frame when the electrical device is in position in the slot of the frame.

These and other features of the invention will be elucidated in conjunction with the accompanying drawings.

Figure 1 shows a perspective view of an embodiment of a housing according to the invention with cut away parts.

Figure 2 shows a cross sectional view of a part of the housing according to figure 1.

Figure 3 shows an enlarged cross sectional view of a part of the housing according to figure 1.

Figure 4 shows a cross sectional top view of a variation of the housing according to figure 1.

Figure 1 shows a perspective view of a housing 1 according to the invention. The housing 1 has a number of outer walls 2, 3,4. The front wall 3 has an opening in which a frame 5 (see figure 2) is arranged. This frameS has a number of slots in which electrical devices 6,7,8 are arranged. The remaining slots are covered with panels 9, 10 such that the housing I is air tight.

Three busbars 11, 12, 13 arc arranged on the back wall of the housing 1 and provide power to the electrical devices 6, 7, 8, when they arc inserted into the slots of the frame 5. A fourth busbar for neutral can also be arranged when necessary. Other busbars or connectors (not shown) are arranged at the back of the housing 1 to transport power to a device like a pump or motor.

Figure 2 shows a cross sectional view ofa part of the housing I of figure 1. The three electrical devices 6, 7, 8 are arranged in the frame 5. A channel 14 is provided on either side of the frame 5 by channel walls 15 and the frame 5. These channels 14 are connected to the air inlet opening 16 and the air outlet opening 17 at the outer wall 3 of the housing.

Air will enter through the air inlet 16 and will flow along the walls of the frame 5 and exchange heat with the frame 5. Due to the heat exchange, the air will move up and exit the channel 14 via the air outlet 17.

Figure 3 shows a further cross sectional detail of the housing 1. Each electronic device 6, 7 has a bottom 18, 19 and sides 20, 21. Inside each device 6,7 a board 22,23 to hold electronic components is arranged.

Some of the electronic components 24,25 are directly arranged to the sides 20, 21 such that the heat of these components 24, 25 can be transferred directly.

The electronic devices 6, 7 are designed such that the sides 20, 21 have heat exchanging contact with the frame 5. The frame 5 is part of the channel 14, such that the heat of the electronic components 24, 25 can be exchanged with the air flowing in the channel 14.

To further increase the heat exchange between the air and the frame 5, ribs 26 are arranged on the frame 5.

The same reference signs are used for the same parts.

The channels 14 on both sides of the frame S are each provided with an undulating plate 30, which is in contact with the walls 15, 5 of the channel 14. This undulating plate 30 increases the heat exchanging surface, similar to the ribs 26 as shown in figure 3. The undulating plate could provide an advantage when manufacturing the housing according to the invention, as the undulating plate 30 can be easily inserted into the channel 14.

Claims

Claims 1. Housing for a low voltage system, which housing comprises: -a frame for housing a numbcr of elcetrical deviccs, such as switchgear, arranged in slots of the frame, which frame has at least a bottom wall, two vertical side walls and a top wall; characterized by -a channel having an air inlet near the bottom of the frame and an air outlet near the top of the frame; wherein the channel is in heat exchanging contact with the frame.
2. Housing according to claim 1, wherein a wall of the channel is one of the vertical side walls of the frame.
3. Housing according to claim 1 or 2, wherein the channel is arranged on both sides of the frame.
4. Housing according to any of the preceding claims, wherein the air inlet and the air outlet of the channel are arranged in an outer wall of the housing.
5. Housing according to any of the preceding claims, wherein ribs are arranged in the channel in heat exchanging contact with the frame
6. Combination of a housing according to any of the preceding claims and at least one electrical device, such as switchgear, wherein the at least one electrical device has at least one heat exchanging surface in contact with the channel.
7. Combination according to claim 6, wherein the at least one heat exchanging surface of the electrical device is in contact with part of the frame.