AIR-COOLED AIR-TO-AIR BOX

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an hall arrangement comprising a vale hall and an air-to-air through-wall bushing.BACKGROUND

[0002] Wall bushings in operation today are normally cooled with natural convection from the surrounding air. One of the demands for a bushing is a certain current level, and this might be hard to fulfil with only air cooling when the bushing is close to the current limit.

[0003] US 1,706,810 discloses a wall bushing with a hollow conductor, within which conductor cooling air is circulated upon heating thereof. A T-shaped air intake tube is arranged at the top of the bushing for both inlet and outlet of the cooling air. <page 1a>SUMMARY

[0004] It is an objective of the present invention to provide an improved cooling of an air-to-air through-wall electrical bushing, typically a high-voltage (HV) bushing, e.g. arranged through a wall of a valve hall.

[0005] According to the invention, there is provided a hall arrangement comprising a valve hall and an air-to-air through-wall bushing according to independent claim 1.

[0006] According to another aspect of the present invention, there is provided a method of providing an air flow through a ventilation channel within an air-to-air through-wall bushing according to independent claim 10. CN 105119214 A discloses a high-voltage wall bushing comprising a conductor and insulation surrounding the conductor. An air-cooling circuit enters from one end of the bushing and exits from the other end. EP 2267870 A1 relates to cooling an electrical connection of a sealed electrical machine and comprises a casing connected to a bushing. The casing has an inlet and an outlet for a cooling fluid. CN 204927997 U discloses a supplementary heat sink of high-pressure wall bushing, wall bushing include conducting rod, porcelain overcoat, insulating layer, binding post and flange. US 2010 / 243288 A1 discloses a high voltage bushing including an elongated electric conductor, a tubular insulator surrounding the conductor, and cooling mechanism for cooling the conductor. The cooling mechanism includes at least one cooling element extending along a fraction of the length of the conductor and in thermal connection with the conductor.

[0007] By means of the ventilation channel with openings (inlet and outlet, respectively) in both ends of the bushing, cooling air may flow through the channel to cool the bushing driven by a pressure difference across the bushing, without the need for forced air circulation by e.g. a fan or compressor or the like. Since the bushing is configured for being arranged through a wall, there is a difference in pressure between the different sides of said wall. There may e.g. be a slight intentional overpressure in the inside of a building to prevent dust and other contaminants from entering the building. By means of the bushing having a ventilation channel with openings in both ends of the bushing, such a pressure difference drives a cooling air flow through the ventilation channel.

[0008] It is to be noted that any feature of any of the aspects may be applied to any other aspect, wherever appropriate. Likewise, any advantage of any of the aspects may apply to any of the other aspects. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

[0009] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / an / the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. The use of "first", "second" etc. for different features / components of the present disclosure are only intended to distinguish the features / components from other similar features / components and not to impart any order or hierarchy to the features / components. Even though some embodiments have been summarized above, the claimed subject matter is defined in the attached claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Embodiments will be described, by way of example, with reference to the accompanying drawings, in which: Fig 1 is a schematic sectional side view of a valve hall having a bushing arranged through a wall thereof, in accordance with some embodiments of the present invention. Fig 2 is a schematic view in longitudinal section of a bushing, in accordance with some embodiments of the present invention. Fig 3 is a schematic view in longitudinal section of an end of the bushing of figure 2, in accordance with some embodiments of the present invention. DETAILED DESCRIPTION

[0011] Embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments are shown. Like numbers refer to like elements throughout the description.

[0012] Figure 1 illustrates a hall arrangement 10 comprising an air-to-air through-wall bushing 1 arranged through a wall 3 of a valve hall 2, according to the present invention. That the bushing is an air-to-air bushing implies that both ends of the bushing are configured to be arranged in ambient air, the inlet and outlet of the ventilation channel opening to said ambient air, not e.g. immersed in an insulation fluid such as e.g. transformer oil or SF 6 gas. That the bushing is a through-wall bushing implies that it is configured to be mounted through a wall of a valve hall, such as a valve hall, housing e.g. a power converter. The bushing 1 may be arranged for either or both of a Direct Current (DC) and an Alternating Current (AC). The bushing 1 may be a HV bushing, i.e. be arranged to pass / connect a HV current through the wall 3. Thus, the bushing 1 passes from air within the hall 2 to air outside of the hall. There is a pressure difference between the air within the hall and the air outside of the hall. There may thus be either an overpressure or an underpressure in the hall. Typically, there is intentionally maintained an overpressure in the hall 2 to prevent dust from entering the hall and pollute the possibly sensitive equipment therein. As illustrated in the figure, there is a first pressure P1 within the hall 2, and a second pressure P2 outside of the hall. If there is an overpressure in the hall, then P1>P2. The bushing may connect to electrical equipment outside of the hall (not shown), e.g. a power transformer.

[0013] Figure 2 illustrates a bushing 1 comprising an electrical conductor 11. The conductor is typically centrally arranged in the bushing, along a central longitudinal axis of the bushing. The conductor may be tubular (hollow) or massive, preferably tubular in the form of a conductor tube 11. The conductor is surrounded, typically concentrically, by electrically insulating insulation comprising a condenser core 13. The insulation may also comprise an outer shell or shed (not shown), typically comprising shed tips for preventing creepage along the outside of the bushing. At each end 15, here a first end 15a and a second end 15b, of the bushing, the conductor is arranged to electrically connect to electrical equipment, e.g. power converter and / or transformer as mentioned above. According to the invention, the first end 15a is an inner end arranged inside of the hall 2, and the second end 15b is an outer end arranged outside of the hall 2.

[0014] The condenser core 13 may be wound directly onto the conductor 11. However, often it is preferred to wind the condenser core 13 onto a winding tube 12, e.g. to allow the conductor 11 to be removed. In accordance with the present invention, cooling air is allowed to flow, e.g. as indicated by the arrows in the figure, through a ventilation channel 14 within the bushing 1, typically longitudinally along the bushing, preferably in contact with the conductor 11, to remove heat from the conductor and from the bushing as a whole. If P1>P2, as in the example of figure 2, the air will flow from the first end 15a of the bushing to the second end 15b, without the need for a fan, compressor or other means for forcing a flow of the cooling air. The ventilation channel 14 may be formed inside and / or outside of the conductor 11. Typically, the winding tube 12 is arranged concentrically around the conductor 11, e.g. such that a, typically concentric, air-gap is formed between the conductor and the winding tube. It that case, the ventilation channel 14, e.g. also substantially concentric, may be formed within said air-gap outside of the conductor. However, if the conductor 11 is hollow, e.g. in the form of a conductor tube, the ventilation channel 14 may additionally or alternatively be formed within the conductor.

[0015] Figure 3 illustrates an end 15 of the bushing 1, e.g. either of the first and second ends 15a and 15b of figure 2. In the embodiment of the figure, ventilation hole(s) or opening(s) 21 are arranged to allow air to pass between the outside of the bushing 1 and a ventilation channel 14 within the bushing. The ventilation hole(s) 21 may either form a ventilation inlet, allowing cooling air from outside of the bushing to enter the ventilation channel 14, if the end 15 is arranged at an overpressure, or a ventilation outlet, allowing cooling air to exit the ventilation channel 14 into the outside of the bushing, if the end 15 is arranged at an underpressure.

[0016] In the embodiment of figure 3, the ventilation channel 14 is formed outside of the conductor 11, between the conductor and the winding tube 12. Thus, the ventilation hole(s) 21 are formed in the winding tube, e.g. through a wall of the winding tube, or in / through a flange or other end connection between the winding tube and the conductor as illustrated in the figure. However, if all or a part of the ventilation channel 14 is formed within the conductor 11, ventilation hole(s) 21 are formed in the conductor tube, e.g. through a wall of the conductor tube, or in an end arrangement of the conductor tube to allow cooling air to enter or exit the conductor tube.

[0017] In some embodiments of the present invention, the ventilation channel 14 is formed outside of the conductor 11. In some embodiments, the ventilation channel 14 is formed in an air-gap between the conductor 11 and a winding tube 12 of the bushing 1. In some embodiments, the winding tube 12 is concentrically arranged outside of the conductor 11. In some embodiments, the ventilation inlet 21 and the ventilation outlet 21 are provided through a respective end connection between the winding tube 12 and the conductor 11 at each end 15a and 15b of the bushing.

[0018] In some embodiments of the present invention, the conductor 11 is in the form of a hollow conductor tube. In some embodiments, additionally or as an alternative to a ventilation channel 14 formed outside of the conductor 11, the ventilation channel is formed inside of the conductor tube 11. In some embodiments, the ventilation inlet 21 and the ventilation outlet 21 are provided through a wall of the conductor tube 11, thus facilitating the ventilation channel being formed within the conductor tube.

[0019] According to the present invention, the bushing 1 is arranged through a wall 3 of a valve hall 2.

[0020] The hall (2) is a valve hall, e.g. housing a power converter, e.g. a Modular Multilevel Converter (MMC). In some embodiments, the hall 2 holds an overpressure P1 which can press cooling air to flow through the ventilation channel 14 from the ventilation inlet 21 arranged within the hall to the ventilation outlet 21 arranged outside of the hall.

Claims

1. A hall arrangement (10) comprising a valve hall (2), and an air-to-air through-wall bushing (1) comprising: a conductor (11); insulation (13) surrounding the conductor; a ventilation channel (14) within the bushing, wherein the ventilation channel (14) comprises: a ventilation inlet (21) at a first end (15a) of the bushing, wherein the first end of the bushing is arranged inside the valve hall; and a ventilation outlet (21) at a second end (15b) of the bushing, wherein the second end of the bushing is arranged outside the valve hall; wherein the bushing (1) is arranged through a wall (3) of the valve hall (2); and wherein a pressure difference between a first pressure (P1) inside the wall (3) of the valve hall (2) and a second pressure (P2) outside the wall (3) of the valve hall (2) is provided, and wherein said inlet and outlet allow cooling air to pass through a ventilation channel (14) within the bushing driven by the provided pressure difference.

2. The hall arrangement of claim 1, wherein the ventilation channel (14) is formed outside of the conductor (11).

3. The hall arrangement of claim 2, wherein the ventilation channel (14) is formed in an air-gap between the conductor (11) and a winding tube (12) of the bushing (1).

4. The hall arrangement of claim 3, wherein the winding tube (12) is concentrically arranged outside of the conductor (11).

5. The hall arrangement of claim 3 or claim 4, wherein the ventilation inlet (21) and the ventilation outlet (21) are provided through a respective end connection between the winding tube (12) and the conductor (11) at each end (15a, 15b) of the bushing.

6. The hall arrangement of any preceding claim, wherein the conductor (11) is in the form of a hollow conductor tube.

7. The hall arrangement of claim 6, wherein the ventilation channel is formed inside of the conductor tube (11).

8. The hall arrangement of claim 7, wherein the ventilation inlet (21) and the ventilation outlet (21) are provided through a wall of the conductor tube (11).

9. The hall arrangement of any preceding claim, wherein the hall (2) holds an overpressure (P1) which can press cooling air to flow through the ventilation channel (14) from the ventilation inlet (21) arranged within the hall to the ventilation outlet (21) arranged outside of the hall.

10. A method of providing an air flow through a ventilation channel (14) within an air-to-air through-wall bushing (1), the bushing being arranged through a wall (3) of a valve hall (2), wherein the bushing comprises: a conductor (11); insulation (13) surrounding the conductor; a ventilation channel (14) within the bushing, wherein the ventilation channel (14) comprises: a ventilation inlet (21) at a first end (15a) of the bushing, wherein the first end of the bushing is arranged inside the valve hall; and a ventilation outlet (21) at a second end (15b) of the bushing, wherein the second end of the bushing is arranged outside the valve hall; the method comprising: providing a pressure difference between a first pressure (P1) inside the wall (3) of the valve hall and a second pressure (P2) outside the wall (3) of the valve hall; and allowing ambient air to pass through the ventilation channel (14) within the bushing, from the ventilation inlet (21) to the ventilation outlet (21), driven by the provided pressure difference.