On-load tap changer for use at sea

Abstract

An on-load tap changer (OLTC) including a housing having a housing body and an upper body attached to the housing body (2). At least a portion of the upper body is provided with a surface inclined relative to a first axis (Z) and oriented such that water flowing along the inclined surface by gravity overflows the edge portion of the inclined surface or is guided to the drainage system of the OLTC. The OLTC also includes: a flange (4) extending substantially around the entire periphery of the upper portion 3 and having holes (11) for bolts distributed around the periphery; and a connecting member (8) positioned between the periphery of the top portion (5) and the flange (4) and facing substantially radially relative to the first axis Z.

Description

Technical Field

[0001] This disclosure generally relates to on-load tap changers (OLTCs). Specifically, this disclosure relates to an improved OLTC design for use in mobile operating conditions, such as at sea. Background Technology

[0002] On-load tap changers (OLTCs) are typically used in static installations in land-based applications. When used in mobile applications (such as offshore applications, like on ships, or land-based vehicles), OLTCs need to withstand high mechanical fatigue and stress associated with high accelerations in different directions caused by motion, waves, and wind. Furthermore, the harsh marine environment presents another challenge. In particular, the top portion of the OLTC is exposed at sea. Facing the environment, the top portion of the OLTC bears its own full weight, as well as the added weight and forces from the clamps and leads of the transformer core it serves.

[0003] OLTC includes a housing formed of a housing body with oppositely opening ends, each end being closed by a corresponding cover attached to the housing body. The housing body can be made of a rigid material, such as fiber-reinforced plastic or metal. However, a large portion of the housing body is made of an electrically insulating material. When the OLTC is subjected to acceleration, different parts of the OLTC are prone to wear, increasing the risk of failure.

[0004] This is usually not a problem for static installations, but new issues arise when OLTCs are used at sea. Furthermore, when used in marine applications, OLTCs are exposed to harsh conditions such as strong winds, salt, sand, and high humidity, further challenging their long-term operational stability.

[0005] Examples of related technologies can be found in the following patent disclosures. CN 209 691 633 U (Langfang Power Supply Company, State Grid Hebei Electric Power Co., Ltd., etc.) discloses an on-load tap changer motor box suitable for outdoor use, which has an upper body designed to protect the OLTC from water. This related technology has a sloping surface and, in one embodiment, also has a groove and outlet serving as a drainage system. This rain cover design is similar to an umbrella arranged around a drive shaft of the OLTC, with the shaft passing through the top of the umbrella. A connector is located at the top of the umbrella rain cover to connect the rain cover to the drive shaft. An open space exists in the lower part of the umbrella, where the OLTC may be exposed to water and moisture from the sides.

[0006] CN 212 587 391 U (Shenzhen Jiaxing Mei Technology Co., Ltd.) discloses a waterproof cap for a transformer switch, which is used to cover the exposed portion of a transformer tap changer to prevent water or snow. The design is arranged to protect such a transformer switch from water from above and sides, wherein a portion of the waterproof cap has a curved profile.

[0007] CN 203205 193 U (Shi Weifeng) discloses a tap changer device in a transformer, which is provided with a cover for a motor housing, wherein the top portion of the upper body (here, the cover) is provided with a spherical shape.

[0008] CN 114 041 198 A (ABB Grids Switzerland AG) shows the OLTC 1, which has a housing made of steel called a tap changer box, and thus implicitly, the cover of the tap changer box is also made of steel. It is also described that tap changer boxes and transformer boxes are typically made of steel.

[0009] US 2016 / 237536 A1 (Forbes Jones Robin M (USA) et al.) shows materials, such as specific steel grades (steel quality) described as materials used in transformers. Summary of the Invention

[0010] The embodiments described in this disclosure are intended to increase the lifespan of OLTCs used at sea.

[0011] According to the first aspect, this objective is achieved by an on-load tap changer according to claim 1, with alternative embodiments defined in the dependent claims. The OLTC includes an upper body. At least a portion of the upper body has a surface inclined relative to a first axis and is oriented such that when the first axis is vertically oriented, water flowing by gravity along the inclined surface overflows from the edge of the inclined surface or is directed to the OLTC's drainage system. The first axis is typically vertically oriented during OLTC use, but its orientation naturally changes over time due to movement caused by wind and waves. The inclined surface of the upper body causes gravity to force water (e.g., rainwater or seawater) out of the OLTC, either across the edge of the OLTC or towards a conduit in the OLTC's drainage system. The drainage system may, for example, connect one or more recesses of the upper body to a drainage conduit, guiding water from the one or more recesses through the OLTC and out of the OLTC through one or more drain outlets. The embodiment includes an on-load tap changer having an upper body and a housing body. The upper body includes or forms a cover configured to cover an open end of the housing body. At least a portion of the upper body is provided with an inclined surface relative to a first axis Z and is oriented such that when the first axis is vertically oriented, water flowing along the inclined surface by gravity overflows from an edge portion of the inclined surface or is guided to a drainage system of the on-load tap changer. The embodiment also includes: a flange extending substantially around the entire periphery of the upper portion and having holes for bolts distributed around the periphery; and a connecting member positioned between the periphery of the top portion and the flange and facing substantially radially relative to the first axis Z.

[0012] In a further embodiment, the upper body includes a collar to pass through a hole in the structural wall. Such embodiments may further include a collar fillet in the portion where the collar engages with the underside of the flange, the collar fillet being configured to receive a seal.

[0013] The embodiments may further include a drainage system having a conduit in the form of one or more channels or grooves configured to guide water from the top portion to one or more outlets 16 on the side of the top portion above the flange for discharge.

[0014] In one embodiment, one or more recesses are arranged on the top portion of the upper body and connected to a drain pipe of the drainage system.

[0015] A portion of the upper body may have an inclined profile. The top portion of the upper body may alternatively have a curved profile. At least a portion of the upper body may have a curved profile.

[0016] In one embodiment, the top portion of the upper body may have a curved profile. In other embodiments, the top portion of the upper body may have a spherical shape. In yet another embodiment, the top portion of the upper body may have a conical profile.

[0017] In one embodiment, the upper body may include a cover configured to cover the open end of the housing body. In another embodiment, at least a portion of the upper body may have a surface inclined relative to a first axis.

[0018] In other embodiments, at least a portion of the periphery of the upper portion may be provided with a flange. The flange may extend substantially around the entire periphery of the upper portion, and at least a portion of the flange may be inclined relative to a first axis and oriented such that when the first axis is vertically oriented, water flowing along the flange by gravity overflows the edge portion of the flange or is guided to the OLTC's drainage system.

[0019] In one embodiment, at least a portion of the on-load tap changer (OLTC) may be made of stainless steel. In another embodiment, the upper body may be made of stainless steel. In another embodiment, the cover may be made of stainless steel. In yet another embodiment, the housing body may be made of stainless steel. The upper portion may be at least partially made of stainless steel. The upper body may be made of stainless steel, and / or the housing body may be made of stainless steel.

[0020] In the embodiments, the stainless steel may be a steel with a pitting resistance equivalent number (PREN) equal to or greater than 40. Attached Figure Description

[0021] All accompanying figures are schematic diagrams not drawn to scale.

[0022] Figure 1 An embodiment of the upper portion of an on-load tap changer is shown.

[0023] Figure 2 This is a side view of an embodiment of the upper portion of an on-load tap changer.

[0024] Figure 3 This is an overview diagram of an on-load tap changer according to an embodiment of this document.

[0025] Figure 4 Is with Figure 2 The illustrated embodiment shows a side view of the upper portion of an on-load tap changer, similar to the one shown, and also includes a top recess forming a depression that is connected to the OLTC's drainage system. The drainage system includes a fluid conduit adapted to allow water to flow from the bottom of the recess to the system's drain outlet. Detailed Implementation

[0026] Embodiments of this disclosure will now be described with reference to the accompanying drawings.

[0027] Figure 1 and Figure 2 An example of the upper body 3 of an on-load tap changer (OLTC) according to an embodiment of this document is shown. The on-load tap changer 1 includes a housing (not in...) Figure 1 (As shown in the figures). The upper body 3 is configured to cover the open end of the housing body 2. In an embodiment, the upper body 3 includes or forms a cover to cover the open end of the housing body 2 for the aforementioned purpose. An exemplary embodiment of the upper body 3 shown in the figures has a rotationally symmetric cross section transverse to a first axis Z indicated by a discontinuity line, and other embodiments may have other cross-sectional shapes, such as square or rectangular. In an embodiment, the top portion 5 of the upper body 3 is provided with an inclined profile. Further, the upper body 3 includes a flange 4, which in an embodiment may be configured to extend substantially around the entire periphery of the upper portion 3. The flange is provided with holes 11 distributed around the periphery of the flange and is configured to allow bolts to pass through the holes.

[0028] The upper body 3 also includes one or more connecting members 8 configured to connect external devices to the interior of the upper body 3 and / or the interior of the on-load tap changer 1 below. The connecting members 8 are positioned between the periphery of the top portion 5 and the flange 4. In the exemplary embodiment shown in the figures, one or more connecting members 8 are positioned on the outer peripheral surface between the periphery of the top portion 5 and the flange 4, and face outwards in a substantially radial or transverse direction relative to the Z-axis. In the overall embodiment, the one or more connecting members 8 face in a substantially radial direction relative to the first axis Z.

[0029] The connecting member 8 is provided with seals configured to prevent water or moisture from entering the on-load tap changer and / or the connector connected to the connecting member 8, while sealing any cables and / or any regulator shaft connected to the connecting member 8. Further, the upper body 3 includes a collar 9 having a rounded corner 10 in the portion where the collar engages with the underside of the flange 4. The collar 9 is configured to pass through a hole in the structural wall 12 (see...). Figure 3 Furthermore, the collar radius 10 is configured to receive a seal (not shown), for example, in the form of an O-ring seal.

[0030] Figure 3 A schematic diagram of an on-load tap changer 1 according to an embodiment of this document is shown. The housing includes a housing body 2 and an upper body 3 attached to the housing body 2 as described above. Figure 3An on-load tap changer 1 is shown installed in a structural wall 12 (such as the housing of a transformer, the deck of a ship, or the body of a land vehicle), wherein the main parts of the on-load tap changer 1 and the housing 2 are inside the structural wall 12, and the upper body 3, together with the connecting member 8, is exposed to the surrounding environment outside the structural wall 12. Figure 3 As shown, the upper body 3 is bolted to the receiving portion (not shown) of the structural wall and / or housing 2. This installation typically includes a seal (not shown) between the underside of the flange 4 and the structural wall 12 to prevent moisture from entering the interior of the structure through any gaps between the upper body 3 and the structural wall 12.

[0031] At least a portion of the upper body 3 is provided with a surface inclined relative to the first axis Z. As an example, a portion of the upper body 3 may be provided with an inclined profile. Alternatively, the top portion 5 of the upper body 3 may be provided with a curved profile.

[0032] Because of the surface or contour provided, moisture and water present on the upper body 3 will flow away or drip off, allowing the water-exposed surface to be drained and dried more quickly. Furthermore, in an embodiment, the connecting member 8 also has an inclined or curved upper surface 7, allowing water and moisture to drip off the connecting member 8. When used, for example, at sea, the tap changer is not only exposed to rain, but seawater may also splash onto it in strong winds. Therefore, if the upper portion can drain and dry more easily, it provides an OLTC with a longer service life when exposed to sea.

[0033] Furthermore, in marine environments, not only is seawater saline, but any fog and rainwater present is also saline. Corrosive elements (such as salt) are present in seawater, and compared to conventional tap switches (where the upper part is more or less flat and water and moisture tend to be present for a long time), tap switches may be exposed to such corrosive elements for a shorter period of time due to the curved or inclined profile of the upper body 3.

[0034] The top portion 5 of the upper body 3 can be provided with a spherical outline, such as... Figure 2 As shown, Figure 2 This is a side view of an exemplary upper portion 5 of an on-load tap changer OLTC 1. The top portion of the upper body 3 may alternatively be provided with a conical profile.

[0035] The upper body 3 may include a cover configured to cover the open end of the housing body 2. As can be seen from several figures, the periphery of the upper body 3 may be provided with a flange 4, either wholly or partially. The flange 4 may be inclined, either wholly or partially, relative to the first axis Z. The flange 4 may alternatively be provided with inclined or curved surfaces or portions thereof, allowing water and moisture to drip off. In the exemplary embodiment shown in the figures, the flange 4 extends substantially around the entire periphery of the upper body 3. The transition region 6 between the flange 4 and other parts is circular, providing a smooth transition and preventing water retention. Furthermore, the upper surface of the flange 4 is inclined relative to the first axis Z. Thus, water and moisture are more easily transported away from the flange 4.

[0036] Figure 4 An exemplary embodiment is shown, comprising a drainage system 14 having conduits in the form of one or more channels or recesses to guide water from the top portion 5 to one or more outlets 16 located on the side of the top portion 5 above the flange 4 for discharge. The sloping surface of the upper body causes gravity to force water (such as rainwater or seawater) out of the OLTC, either across the edge of the OLTC or towards the conduits of the drainage system. In a further embodiment, the drainage system may, for example, connect one or more recesses 18, forming one or more recesses arranged on the top portion 5 of the upper body 3 and connected to the drainage conduits of the drainage system 14, guiding water from the one or more recesses 18 through the upper portion 3 of the OLTC and out of the OLTC through one or more drainage outlets 16. The upper portion may be at least partially made of stainless steel. Stainless steel is a superior material when exposure to harsh environments, such as those present in marine applications, is required. Other small or large parts or details may be made of stainless steel. The upper body 3 may be made of stainless steel, and / or the shell body 2 may be made of stainless steel. The stainless steel used may be a steel grade with a pitting resistance equivalent number (PREN) equal to or greater than 40.

Claims

1. An on-load tap changer (1), the on-load tap changer comprising an upper body (3) and a housing body (2), the upper body (3) including or forming a cover configured to cover an open end of the housing body (2), wherein, At least a portion of the upper body (3) is provided with an inclined surface relative to a first axis (Z), and is oriented such that when the first axis is vertically oriented, water flowing along the inclined surface by gravity overflows the edge of the inclined surface or is guided to the drainage system of the on-load tap changer (1), characterized in that: Flange (4), which extends substantially around the entire periphery of the upper portion (3) and has holes (11) for bolts distributed around the periphery. A connecting member (8) is positioned between the periphery of the top portion (5) and the flange (4) and faces substantially radially relative to the first axis Z.

2. The on-load tap changer (1) according to claim 1, wherein, The upper body (3) includes a collar (9) for passing through a hole in the structural wall (12).

3. The on-load tap changer (1) according to claim 2, the on-load tap changer further includes a collar fillet (10) in the portion where the collar meets the lower side of the flange (4), the collar fillet (10) being configured to receive a seal.

4. The on-load tap changer (1) according to any one of the preceding claims, wherein, The connecting member (8) is provided with an inclined or curved upper surface (7).

5. The on-load tap changer (1) according to any one of the preceding claims, the on-load tap changer further comprising a drainage system (14) having a conduit in the form of one or more channels or grooves, the conduit being configured to guide water from the top portion (5) to one or more outlets (16) on the side of the top portion (5) above the flange (4) for discharge.

6. The on-load tap changer (1) according to any one of the preceding claims, the on-load tap changer further comprising one or more recesses (18) arranged on the top portion (5) of the upper body (3) and connected to the drain conduit of the drainage system (14).

7. The on-load tap changer (1) according to any one of the preceding claims, wherein, At least a portion of the upper body (3) is provided with an inclined profile.

8. The on-load tap changer (1) according to any one of the preceding claims, wherein, At least a portion of the upper body (3) is provided with a curved profile.

9. The on-load tap changer (1) according to any one of the preceding claims, wherein, The top portion (5) of the upper body (3) is provided with a curved profile.

10. The on-load tap changer (1) according to any one of the preceding claims, wherein, The top portion (5) of the upper body (3) is provided with a spherical shape.

11. The on-load tap changer (1) according to any one of the preceding claims, wherein, The top portion (5) of the upper body (3) is provided with a conical profile.

12. The on-load tap changer (1) according to any one of the preceding claims, wherein, At least a portion of the flange (4) is inclined relative to the first axis (Z) and oriented such that when the first axis is vertically oriented, water flowing along the flange (4) by gravity overflows the edge portion of the flange (4) or is guided to the drainage system of the on-load tap changer (1).

13. The on-load tap changer (1) according to any one of the preceding claims, wherein, The upper body (3) is made of stainless steel.

14. The on-load tap changer (1) according to any one of the preceding claims, wherein, The housing body (2) is made of stainless steel.

15. The on-load tap changer (1) according to any one of the preceding claims, wherein, The stainless steel is a type of steel with a pitting resistance equivalent number (PREN) equal to or greater than 40.

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