阅读说明：本技术 具有带用于压力补偿和体积补偿的筒状波纹件的组件的电气设备 (Electrical device having an assembly with cylindrical bellows for pressure and volume compensation ) 是由 Y·B·拉索德 A·A·乔希 K·I·乔汉 于 2018-07-13 设计创作，主要内容包括：本发明提供了一种充油型电气设备,其包括用于充油和密闭地密封电气设备的组件。该组件包括筒状波纹件,该筒状波纹件通过一个或更多个装配件安装在电气设备的板上。波纹件在电气设备中提供压力补偿和体积补偿。该波纹件包括筒体,该筒体具有用于膨胀和收缩以提供补偿的多个卷褶。该波纹件还包括两个盖,这两个盖在筒体的两个端部处与筒体附接。每个盖包括筒状部分,该筒状部分在第一端部处敞开且在第二端部处闭合。第一端部终止于环形面,该环形面用于将盖安装在筒体的相应端部处的卷褶上。第二端部包括开口,该开口用于充油和密闭地密封电气设备以及将波纹件安装在板上。(The present invention provides an oil-filled electrical apparatus including an assembly for filling oil and hermetically sealing the electrical apparatus. The assembly includes a cylindrical bellows mounted to a plate of the electrical device by one or more fittings. The bellows provides pressure compensation and volume compensation in the electrical apparatus. The bellows includes a cylinder having a plurality of convolutions for expanding and contracting to provide compensation. The bellows also includes two covers attached to the can at both ends of the can. Each cover includes a barrel portion that is open at a first end and closed at a second end. The first end terminates in an annular face for mounting the cover on the convolutions at the respective end of the can. The second end includes an opening for filling oil and hermetically sealing the electrical equipment and mounting the bellows on the plate.)

1. An oil-filled electrical apparatus comprising an assembly for oil-filling and hermetically sealing the electrical apparatus, wherein the assembly comprises a cylindrical bellows (300), the cylindrical bellows (300) being mounted on a plate (602) of the electrical apparatus by one or more fittings (310, 312) for pressure compensation and volume compensation in the electrical apparatus, wherein the cylindrical bellows comprises:

a barrel (308), the barrel (308) having a plurality of convolutions for expanding and contracting to provide the pressure compensation and volume compensation; and

two covers (304, 306) attached to the barrel at both ends of the barrel, wherein each cover comprises a barrel portion (402), the barrel portion (402) being open at a first end (406) and closed at a second end (408), wherein the first end terminates in an annular face (404), the annular face (404) being for mounting the cover on a crimp at the respective end (502, 504) of the barrel, and wherein the second end comprises an opening (412), the opening (412) being for oil filling and hermetically sealing the electrical apparatus and mounting the barrel bellows on the plate by means of the one or more fittings.

2. The oil-filled electrical apparatus of claim 1, wherein each of the one or more fittings of the assembly is mounted on a respective cover and at the second end of the cylindrical portion for oil filling and hermetically sealing the electrical apparatus, and wherein a first fitting (312) of the one or more fittings comprises a square opening (702) at one end, the square opening (702) for applying torque to attach the bellows with the plate of the electrical apparatus.

3. The oil-filled electrical apparatus of claim 2, wherein the assembly further comprises two or more clips, wherein each clip holds the cylindrical bellows at a junction between the crimp and the plate.

4. The oil-filled electrical apparatus of claim 3, wherein the cylindrical bellows is attached to the plate such that a contact region (604) held under preload is located at the junction between the cylindrical bellows and the plate and at a periphery of the first fitting.

5. The oil-filled electrical apparatus of claim 1, wherein the cylindrical bellows of the assembly is designed for axial movement about an axis (302) to provide the pressure and volume compensation.

6. The oil-filled electrical apparatus of claim 2, wherein the first fitting is made of steel to provide stiffness and damping when the cylindrical bellows is filled with oil.

7. The oil-filled electrical apparatus of claim 1, wherein each cover comprises a protrusion (410) on the second end and proximate to a fitting area for providing strength to the cylindrical bellows during manufacturing, assembly, and running operations.

8. The oil-filled electrical apparatus of claim 1, wherein the cylinder having the plurality of convolutions is made of a thin sheet of stainless steel by a hydroforming process.

9. The oil-filled electrical device of claim 1, wherein the electrical device is an instrument transformer.

10. A cylindrical bellows (300) for pressure compensation and volume compensation in an oil-filled electrical apparatus, the cylindrical bellows comprising:

a barrel (308), the barrel (308) having a plurality of convolutions for expanding and contracting to provide the pressure compensation and volume compensation; and

two covers (304, 306) attached to the barrel at both ends of the barrel, wherein each cover comprises a barrel portion (402), the barrel portion (402) being open at a first end (406) and closed at a second end (408), wherein the first end terminates in an annular face (404), the annular face (404) being for mounting the cover on a crimp at the respective end (502, 504) of the barrel, and wherein the second end comprises an opening (412), the opening (412) being for oil filling and hermetically sealing the electrical apparatus and mounting the cylindrical bellows on the plate by one or more fittings (310, 312).

Technical Field

The present invention generally relates to an inflatable bellows (balloon) for an electrical apparatus. More particularly, the present invention relates to an oil-filled electrical apparatus including an assembly with cylindrical bellows for pressure compensation and volume compensation in the electrical apparatus.

Background

The expansion bellows is used in manufacturing to simplify the assembly, evacuation/drying and oil filling processes. Disc-shaped corrugated parts are commonly used in electrical devices, such as transformers, such as Capacitive Voltage Transformers (CVTs). The disk corrugator consists of two disks and a fitting. Fig. 1 shows a cross-sectional view of a disc-shaped bellows attached to a plate of an electrical device. The two disks are welded at the edges and near the center. The disk-shaped bellows is installed using a fitting at the bottom. Sometimes, additional supports are provided to provide additional support.

There are problems with the use of such a corrugated disk in oil-filled electrical equipment. Before its intended life, oil may leak due to fatigue failure (e.g., due to cracking/deformation). Alternatively, oil leakage may occur due to cracks generated at the welded region (or joint). In addition, the axial movement for oil compensation may be insufficient in view of the limited capacity of the disc-shaped bellows.

These problems may be related to the stresses to which the disk-shaped corrugated member is subjected during processing/manufacturing, shipping and/or normal operation of such electrical equipment. Processing may typically involve assembly, vacuum drying, heating, oil filling and sealing (under pressure). The disc is found to deform several times during processing (e.g., vacuum and over-extrusion).

As shown in fig. 2, additional supports are typically used to provide support during transport. Since the oil filled bellows has only a bottom support, there is little support at the edges, it can continue to vibrate during transport (e.g., due to rough road conditions) and can be exposed to large impacts. Thus, the welded joint and the support at the bottom disc may be subjected to severe stresses, which may lead to cracks or deformations. If the corrugated member is somehow subject to shipping, it is still susceptible to failure. This is due to the effect of the stresses encountered during transport and to the stress concentrations during its normal service life (about 30 years or so). This part of the fault is considered to be a fault of the electrical equipment (e.g. a transformer fault).

Accordingly, there is a need for an oil-filled electrical apparatus having an assembly with an expanding bellows that is robust enough to withstand handling and shipping, and is capable of withstanding stresses during normal operation (i.e., over the life of the transformer).

Disclosure of Invention

The present invention provides an oil-filled electrical apparatus comprising an assembly for filling oil and hermetically sealing the electrical apparatus. The electrical device may be a transformer, such as an instrument transformer (transformer).

The assembly includes a cylindrical bellows mounted on a plate of the electrical device by one or more fittings. The cylindrical bellows is used for pressure compensation and volume compensation in the electrical apparatus. In an embodiment, the cylindrical bellows is designed for axial movement to provide the pressure compensation and volume compensation.

The cylindrical bellows includes a cylinder having a plurality of convolutions (convolutions) and two covers. The cylinder may be made of a stainless steel sheet by a hydroforming process. The convolutions are used to expand and contract (as needed due to oil temperature changes) to provide the pressure and volume compensation. The two covers are attached to the barrel at both ends of the barrel.

Each cover includes a barrel portion that is open at a first end and closed at a second end. The first end of the barrel terminates in an annular face for mounting the cap on a crimp at the respective end of the barrel. The second end of the barrel portion includes an opening. The opening is used for filling the electrical equipment with oil and for hermetically sealing the electrical equipment when the oil filling is completed. In addition, the opening is used to mount the cylindrical bellows on the plate by the one or more fittings. The plate may be a plate on the housing of the electrical device, the plate having corresponding openings for the oil filling and hermetically sealing (e.g. by using O-rings). Each cap may have a projection on the second end proximate the fitting area for providing strength to the cylindrical bellows during manufacturing, assembly and running operations.

In the assembly, the cylindrical bellows is mounted on the plate by one or more fittings. In one embodiment, the assembly comprises two fittings, wherein each fitting is provided on a respective cover of the cylindrical bellows at the second end. The assembly may be used to fill oil, hermetically seal the electrical equipment and/or mount the cylindrical bellows on the plate. Here, a first fitting of the two fittings (e.g., a fitting for engaging the plate) includes a square opening at an end of the fitting. The opening may be used to apply a torque (e.g. by using a suitable tool) to attach the bellows with the plate of the electrical device. For example, the fitting may be threaded for attachment with the plate (e.g., a plate with a corresponding interface), and the bellows may be rotated using a suitable tool to mount the bellows on the plate. The first fitting may be made of steel to provide stiffness and damping when the cylindrical bellows is filled with oil.

In one embodiment, the assembly further comprises two or more clamps to hold the bellows at the junction between the bellows and the plate. Here, clamping is performed between the crimp (at the end of the cylinder) and the plate. The number of the clamping members may be determined according to the size of the corrugated member. In one embodiment, four clamps are used. Thus, the cylindrical bellows is attached to the plate such that: the contact region which is held under pretensioning is located at the joint between the cylindrical bellows and the plate and at the outer periphery of the first fitting part (periphery).

Drawings

The subject matter of the invention will be explained in more detail hereinafter with reference to exemplary embodiments shown in the drawings, in which:

figure 1 (prior art) shows a disc-shaped bellows mounted on a plate of an electrical apparatus;

figure 2 (prior art) shows a support provided for a disc-shaped bellows;

FIG. 3 shows a perspective cross-sectional view of a cylindrical bellow (300) according to an embodiment of the invention;

FIG. 4 shows a lid of a cylindrical bellows;

FIG. 5 shows a cylinder of the cylindrical bellows having a plurality of convolutions;

fig. 6 shows a contact area of an assembly of cylindrical corrugated members with a plate of an electrical apparatus according to an embodiment of the present invention;

FIG. 7 illustrates an assembly of components according to an embodiment of the invention;

fig. 8 shows a mounted state in which a component is mounted on a board by a fitting according to an embodiment of the present invention; and

fig. 9 is an enlarged view of the holder of the cylindrical bellows shown in the mounted state of the assembly.

Detailed Description

The present invention relates to electrical equipment of the oil-filled type, such as but not limited to transformers, distribution transformers. The invention provides an electrical device with an assembly for oil-filled and hermetically sealed (hermetical) electrical devices. The assembly includes an expansion system for hermetically sealed electrical equipment. The expansion system functions as a pressure compensating and volume compensating device and overcomes the problems of conventional disc-shaped bellows used in such electrical apparatuses. The expansion system of the present invention comprises cylindrical bellows.

The cylindrical bellows is designed to operate in an axial direction with minimal lateral movement. When the oil expands due to a change in a parameter (e.g., temperature, pressure, volume, etc.), the cylindrical bellows will expand axially and vice versa. The cylindrical bellows in a hermetically sealed system maintains the pressure within the desired operating limits even if the oil pressure varies significantly under various conditions (e.g., during processing, during climatic changes, etc.).

Fig. 3 shows a perspective cross-sectional view of a cylindrical bellows (300). The cylindrical bellows expands/contracts axially (along 302) to provide pressure compensation and volume compensation. As shown, the cylindrical bellows includes two covers (304, 306), the two covers (304, 306) being attached to a cylinder (308) that includes a plurality of convolutions. The two covers (i.e., top and bottom covers) are attached (e.g., welded) with crimps (e.g., top crimps, bottom crimps) at the ends to form the desired shape of the cylindrical bellows for pressure compensation and volume compensation (e.g., by expansion or contraction of the cylinder 308 about the axis 302).

As shown in fig. 4, each cap is generally cylindrical having a cylindrical portion (402) and an annular face (404) toward the end. Thus, the cylindrical portion is open at the first end (406) and closed at the second end (408), which forms a U-shape of the lid. This hollow U-shape provides a number of benefits. Some of these benefits are oil savings, space provision and, most importantly, ease of installation. Furthermore, an opening (412) provided at the second end makes it possible to fill oil, hermetically seal, and mount the bellows on the plate.

The space created by the shape of the cover provides multiple uses. This space is used for assembly (see 310, 312 in fig. 3), oil filling (top cover (302)), fixing the bellows (top cover (302) and bottom cover (304)), and optionally for torque application described later. The flat annular face of the bottom head rests on top of the main oil unit system. The bulge (410) near the fitting area imparts strength to the bellows during factory processing and during vacuum and pressure rise in running operations, which minimizes any permanent deformation changes to the bellows.

A cartridge (308) having a plurality of convolutions is shown in fig. 5. The barrel expands and contracts in the axial direction (i.e., around 302) to provide the required compensation in response to changes in oil temperature (or pressure, volume, etc.). The component may be made from a thin sheet of stainless steel by a hydroforming process. The size of the barrel depends on certain parameters such as, but not limited to, stroke length (e.g., expansion and contraction), operating pressure, and number of life cycles. The number of convolutions can be adjusted according to the desired bellows capacity and requirements (e.g., requirements for compensating for thermal expansion of oil volume and pressure changes). The greater the number of pleats, the greater the amount of expansion and contraction. The convolutions (502, 504) at the ends are where the covers (304, 306) are attached.

As shown in fig. 3, two fittings are provided, a top fitting (310) attached to the top cover (304) and a bottom fitting (312) on the bottom cover (306). The cylindrical corrugated member is mounted on the top of the main assembly of the electrical apparatus. The cylindrical bellows is arranged on a plate (602), for example a plate of a transformer, to be peripherally held under preload at a contact area (604) as highlighted in fig. 6.

The bellows is attached to the plate (602) by a base fitting (312). In the embodiment shown in FIG. 7, the flat annular surface of the bottom cover and the design of the bottom fitting help to generate the preload force. The bottom fitting is a compact component, which may be made of steel and is specifically designed to mount the bellows on the main unit. In one embodiment, the bottom end of the fitting has threads (not shown) for securing to the top of the unit. In the embodiment of fig. 7, a square opening (702) is provided (e.g., by broaching) in the top of the bottom fitting (312). This may be used to apply torque (e.g., similar to a nut). This can help prevent stress from being caused when the corrugated member is fixed with the main unit. Due to the provision of the square opening, this square opening can be used (for example, by means of a suitable tool) to rotate the bellows in order to fix it to the main unit (for example, to a corresponding fitting of the transformer). The bottom fitting may also provide stiffness and damping when the bellows is full of oil and has to withstand random vibrations and shocks.

Optionally, as shown in fig. 8, the bellows is attached to the plate using one or more clamps (retaining clamps 802, 804). The number of clamps may be determined based on the capacity of the bellows. In one embodiment, four clamps are used. As shown in fig. 9, the clips securely hold the bellows at the joints (e.g., 806, 808) between the convolutions/cover and the plate at the ends. The clamp helps to reduce fatigue stresses generated during life cycle operation.

Thus, the electrical device with the expansion system of the present invention is better able to withstand random vibrations and impacts in different directions than conventional electrical devices. The cylindrical bellows is designed for axial movement and remains securely installed during transport and during normal operation after installation in the field. Furthermore, the oil volume compensation is significantly higher compared to the disc bellows, since the compensation is provided axially (due to the convolutions). An optional square opening on the bottom fitting is used to apply torque for proper securement. The optional support (clamp) provided at the bottom also helps to minimize the stresses experienced during transport.