Gas-insulated instrument transformer

Abstract

To provide a gas-insulated instrument transformer with improved insulation performance. [Solution] The gas-insulated instrument transformer (1) comprises a core, a primary coil (13), a secondary coil, a potential fixing plate (20), a high-voltage shield (17), a first insulator (21), and a second insulator (22). The first insulator (21) is placed between the primary coil (13) and the potential fixing plate (20). The second insulator (22) is placed between the primary coil (13) and the high-voltage shield (17).

Description

Technical Field

[0001] The present disclosure relates to a transformer for gas-insulated instruments.

Background Art

[0002] Conventionally, there has been a transformer for gas-insulated instruments in which a coil is wound around a core, a high-voltage shield is provided outside the coil, and these are housed in a container together with an insulating gas (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the transformer for insulating instruments shown in FIG. 5 of Patent Document 1, problems may occur when a steep wave such as a lightning impulse is applied. When a steep wave causes a potential difference between the high-voltage coil and the high-voltage shield and the electric field in the gap becomes high, discharge may occur between the high-voltage coil and the high-voltage shield.

[0005] One aspect of the present disclosure aims to provide a transformer for gas-insulated instruments with improved insulation performance.

Means for Solving the Problems

[0006] To solve the above problems, a gas-insulated instrument transformer according to Embodiment 1 of the present disclosure is a gas-insulated instrument transformer having a container filled with insulating gas, comprising: a core; a secondary coil wound around the core; a primary coil wound around the outside of the secondary coil; a potential fixing plate disposed outside the primary coil; a high-voltage shield attached to the outer circumference of the potential fixing plate; and at least one of a flexible first insulator disposed between the outermost part of the primary coil and the potential fixing plate, and a flexible second insulator disposed between the outermost part of the primary coil and the high-voltage shield.

[0007] In the gas-insulated instrument transformer according to Embodiment 2 of this disclosure, in Embodiment 1 described above, the first insulator or the second insulator may be made of rubber.

[0008] In the gas-insulated instrument transformer according to embodiment 3 of the present disclosure, in embodiment 1 or 2 described above, the first insulator may be tightened by the potential fixing plate and deformed to fit the potential fixing plate.

[0009] In the gas-insulated instrument transformer according to Embodiment 4 of the present disclosure, in any of Embodiments 1 to 3 described above, the second insulator may be tightened by the high-voltage shield and deformed to fit the high-voltage shield.

[0010] A gas-insulated instrument transformer according to Embodiment 5 of the present disclosure may, in any of Embodiments 1 to 4 above, comprise the first insulator and the second insulator, wherein the first insulator and the second insulator are integrally molded.

[0011] A gas-insulated instrument transformer according to embodiment 6 of the present disclosure comprises the first insulator and the second insulator in any of embodiments 1 to 5 above, wherein the Young's modulus and thickness of the first insulator and the Young's modulus and thickness of the second insulator may be different from each other. [Effects of the Invention]

[0012] According to one aspect of this disclosure, insulation performance can be improved. [Brief explanation of the drawing]

[0013] [Figure 1] This is a longitudinal cross-sectional view showing the overall configuration of a gas-insulated instrument transformer according to Embodiment 1 of this disclosure. [Figure 2] This is a schematic cross-sectional view of the area around the first and second insulators of a gas-insulated instrument transformer according to Embodiment 1. [Figure 3] This is a cross-sectional view showing the high-voltage shield and potential fixing plate of a gas-insulated instrument transformer according to Embodiment 1. [Figure 4] This figure shows the mounting structure of the high-voltage shield and potential fixing plate of the gas-insulated instrument transformer according to Embodiment 1. [Figure 5] This figure shows the change in potential between the potential fixing plate and the primary coil of a gas-insulated instrument transformer according to Embodiment 1. [Figure 6] This is a diagram corresponding to Figure 2 of the gas-insulated instrument transformer according to Embodiment 2. [Figure 7] This is a diagram corresponding to Figure 2 of a gas-insulated instrument transformer according to Embodiment 3. [Figure 8] This is a diagram corresponding to Figure 2 of a gas-insulated instrument transformer according to Embodiment 4. [Modes for carrying out the invention]

[0014] [Embodiment 1] Hereinafter, the gas-insulated instrument transformer 1 according to Embodiment 1 of this disclosure will be described with reference to Figures 1 to 4.

[0015] [Outline configuration of a gas-insulated instrument transformer] Figure 1 is a longitudinal cross-sectional view showing the schematic configuration of a gas-insulated instrument transformer 1 according to Embodiment 1. As shown in Figure 1, the gas-insulated instrument transformer 1 comprises a core 11, a core holding member 12, a primary coil 13, a primary winding 14, a secondary coil 15, a secondary winding 16, and a high-voltage shield 17.

[0016] The transformer 1 for gas-insulated instruments is, for example, incorporated and used in a gas-insulated switchgear (GIS) not shown in the figures. The transformer 1 for gas-insulated instruments is an electrical device that receives a high voltage from the gas-insulated switchgear on the primary coil 13 side and transforms it into a secondary-side voltage suitable for measuring instruments connected to the secondary coil 15.

[0017] The transformer 1 for gas-insulated instruments is, for example, a three-phase transformer for gas-insulated instruments. Note that in Fig. 1, only the components of the transformer for gas-insulated instruments for one phase out of the three phases are shown.

[0018] The transformer 1 for gas-insulated instruments has a container not shown in the figures. The container houses a core 11, a core holding member 12, a primary coil 13, a primary winding form 14, a secondary coil 15, a secondary winding form 16, a high-voltage shield 17, etc. Further, the container is filled with an insulating gas such as dry air. Note that the insulating gas is not limited to dry air and may be, for example, SF6.

[0019] The core 11 is made of, for example, iron and is composed of a laminate of steel plates. The core 11 is formed in a rectangular ring shape. The core holding member 12 holds the core 11 so as to cover the periphery of the core 11.

[0020] On the upper side portion of the core 11, the secondary coil 15 is wound via the secondary winding form 16. The secondary coil 15 is formed by winding a conductor in a cylindrical shape around the periphery of the upper side portion of the core 11.

[0021] On the outside of the secondary coil 15, the primary coil 13 is wound via the primary winding form 14. The primary coil 13 is formed by winding a conductor concentrically with the secondary coil 15. An annular high-voltage shield 17 for relaxing the electric field is disposed on the outside of the primary coil 13.

[0022] [Configuration around the first insulator and the second insulator] Next, the configuration of the area around the first insulator 21 and the second insulator 22 in the gas-insulated instrument transformer 1 will be described with reference to Figures 2 and 3. Figure 2 is a schematic cross-sectional view of the area around the first insulator 21 and the second insulator 22 of the gas-insulated instrument transformer 1.

[0023] As shown in Figure 2, the gas-insulated instrument transformer 1 further comprises a potential fixing plate 20, a first insulator 21, and a second insulator 22. The primary coil 13 is multi-layer wound with insulating film 18 interposed between the layers. In Figure 2, the conductors in the outermost layer and the next innermost layer of the multiple layers of the primary coil 13 are illustrated. Also in Figure 2, the external shape of the primary coil 13 is schematically shown. The insulating film 18 is wound around each layer of the primary coil 13. The surface shape of the outermost insulating film 18 may not be flat, but may have irregularities, reflecting the shape of the primary coil 13.

[0024] The potential fixing plate 20 is made of, for example, a conductive plate and is positioned outside the outermost periphery 131 of the primary coil 13, covering the outermost insulating film 18. Although not shown, the potential fixing plate 20 is connected to the end of the winding of the primary coil 13 and also to the high-voltage shield 17. The primary coil 13 is electrically connected to the high-voltage shield 17 via the potential fixing plate 20. The high-voltage shield 17 is supplied with a high-voltage primary voltage from the gas-insulated switchgear.

[0025] Figure 3 is a cross-sectional view showing the high-voltage shield 17 and potential fixing plate 20 of the gas-insulated instrument transformer 1. As shown in Figure 3, the potential fixing plate 20 is made of, for example, a conductive plate and is formed in a cylindrical shape. The potential fixing plate 20 has an open ring shape with a gap G provided.

[0026] A high-voltage shield 17 is attached to the outer circumference of the potential fixing plate 20. The high-voltage shield 17 has a first member 171 and a second member 172. As shown in Figure 3, the first member 171 has a cross-section that is curved in a C shape. The second member 172 also has a cross-section that is curved in a C shape. A gap is formed between the first member 171 and the second member 172.

[0027] The first insulator 21 is a flexible insulator. The first insulator 21 is, for example, rubber. As shown in Figure 2, the first insulator 21 is placed between the outermost periphery 131 of the primary coil 13 and the potential fixing plate 20. The first insulator 21 is placed between the insulating film 18 wrapped around the outermost periphery 131 of the primary coil 13 and the potential fixing plate 20. The first insulator 21 may be in sheet form and wrapped around the primary coil 13 and the insulating film 18. Alternatively, the first insulator 21 may be ring-shaped (cylindrical) and cover the periphery of the primary coil 13. The cross-sectional shape of the first insulator 21 is rectangular.

[0028] For example, the material of the first insulator 21 can be nitrile rubber (NBR), chloroprene rubber (CR), ethylene rubber (EPDM), butyl rubber (IIR), fluororubber (FPM), silicone rubber (SI), or natural rubber (NR).

[0029] The first insulator 21 is tightened by the potential fixing plate 20 and deformed to fit the potential fixing plate 20. This makes it possible to effectively fill the gap between the primary coil 13 and the potential fixing plate 20. Preferably, the first insulator 21 also fits the insulating film 18 that covers the outermost periphery 131 of the primary coil 13.

[0030] The second insulator 22 is a flexible insulator. The second insulator 22 is, for example, a flexible rubber. The material of the second insulator 22 may be the same as or different from the material of the first insulator 21. The second insulator 22 is placed between the outermost part 131 of the primary coil 13 and the high-voltage shield 17.

[0031] The second insulator 22 is positioned between the insulating film 18, which is wound around the outermost periphery 131 of the primary coil 13, and the high-voltage shield 17. The second insulator 22 may be in sheet form and wound around the primary coil 13 and the insulating film 18. Alternatively, the second insulator 22 may be ring-shaped (cylindrical) and cover the periphery of the primary coil 13. The cross-sectional shape of the second insulator 22 is rectangular.

[0032] The second insulator 22 is tightened by the high-voltage shield 17 and deformed to fit the high-voltage shield 17. This allows the gap between the primary coil 13 and the high-voltage shield 17 to be filled well. Preferably, the second insulator 22 also fits the insulating film 18 that covers the outermost periphery 131 of the primary coil 13.

[0033] The thickness of the second insulator 22 and the thickness of the first insulator 21 are different. Specifically, taking into account that the high-voltage shield 17 is further away from the outermost part 131 of the primary coil 13 than the potential fixing plate 20, the thickness of the second insulator 22 is greater than the thickness of the first insulator 21.

[0034] Furthermore, the Young's modulus of the second insulator 22 and the Young's modulus of the first insulator 21 may be different from each other. For example, if the clamping force of the high-voltage shield 17 on the outermost periphery 131 of the primary coil 13 is greater than the clamping force of the potential fixing plate 20 on the outermost periphery 131 of the primary coil 13, the Young's modulus of the second insulator 22 may be greater than that of the first insulator 21.

[0035] [Mounting structure between high-voltage shield and potential fixing plate] Next, the mounting structure of the high-voltage shield 17 and the potential fixing plate 20 in the gas-insulated instrument transformer 1 will be explained with reference to Figures 3 and 4.

[0036] Figure 4 shows the mounting structure of the high-voltage shield 17 and the potential fixing plate 20 of the gas-insulated instrument transformer 1. As shown in Figure 4, the high-voltage shield 17 is attached to the potential fixing plate 20 by bolts B.

[0037] Here, the high-voltage shield 17 has a hole 170 for inserting a bolt B. Also, a mounting portion 19 is fixed to the potential fixing plate 20, and a bolt hole 191 is provided in the mounting portion 19.

[0038] The high-voltage shield 17 is fixed to the potential fixing plate 20 by inserting bolts B through holes 170 in the high-voltage shield 17 and attaching them to bolt holes 191 in the mounting portion 19. Specifically, as shown in Figure 3, the high-voltage shield 17 is fixed to the potential fixing plate 20 by fastening with four bolts B.

[0039] [Effects of Embodiment 1] Since the high-voltage shield 17 is formed by bending a sheet of metal, it is difficult to process it into a shape that follows a perfect circle, and distortion may occur. When a distorted high-voltage shield 17 is attached to the potential fixing plate 20, the potential fixing plate 20 deforms along the high-voltage shield 17. In addition, the outer shape of the primary coil 13 is not necessarily a perfect circle, and distortion may occur during the coil winding process.

[0040] Therefore, if the first insulator 21 and the second insulator 22 are absent, even if the primary coil 13 is tightened with the potential fixing plate 20, a gap may occur between the primary coil 13 and the insulating film 18 and the potential fixing plate 20. Similarly, a gap may occur between the primary coil 13 and the insulating film 18 and the high-voltage shield 17.

[0041] According to the gas-insulated instrument transformer 1 of Embodiment 1, a flexible first insulator 21 is placed between the outermost 131 of the primary coil 13 and the potential fixing plate 20, and a flexible second insulator 22 is placed between the outermost 131 of the primary coil 13 and the high-voltage shield 17.

[0042] According to the above configuration, tightening the potential fixing plate 20 deforms the flexible first insulator 21. The deformed first insulator 21 fits onto the potential fixing plate 20, thereby reducing the gap between the outermost part 131 of the primary coil 13 and the potential fixing plate 20. Similarly, the high-voltage shield 17 comes into contact with the second insulator 22, causing it to deform. The deformed second insulator 22 fits onto the high-voltage shield 17, thereby reducing the gap (air gap) between the outermost part 131 of the primary coil 13 and the high-voltage shield 17.

[0043] The first insulator 21 fills the gap between the outermost part 131 of the primary coil 13 and the potential fixing plate 20. The second insulator 22 fills the gap between the outermost part 131 of the primary coil 13 and the high-voltage shield 17. This prevents discharge even when a sharp wave, such as a lightning impulse, is applied. This eliminates the need to adjust the size of the gaps, improving the ease of assembly of the gas-insulated instrument transformer 1.

[0044] Here, Figure 5 schematically shows the equipotential lines between the potential fixing plate 20 and the primary coil 13 of the gas-insulated instrument transformer 1. The left side of Figure 5 shows equipotential line E1 when the first insulator 21 and the second insulator 22 are not present between the potential fixing plate 20 and the primary coil 13. On the other hand, the right side of Figure 5 shows equipotential line E2 when the first insulator 21 and the second insulator 22 are present between the potential fixing plate 20 and the primary coil 13.

[0045] As shown in the right-hand diagram of Figure 5, by placing the first insulator 21 and the second insulator 22 between the potential fixing plate 20 and the primary coil 13 to reduce the potential sharing, the curvature of the equipotential line E2 can be made smaller than that of the equipotential line E1 in the left-hand diagram of Figure 5. This makes it possible to mitigate the concentration of the electric field at the end of the potential fixing plate 20. If the second insulator 22 is absent, it is preferable that the width of the first insulator 21 (the dimension in the axial direction of the primary coil 13) is greater than the width of the potential fixing plate 20.

[0046] Furthermore, the second insulator 22 prevents the gap between the high-voltage shield 17 and the outermost part 131 of the primary coil 13 from becoming too small due to assembly errors. This suppresses the rise in the electric field at the end of the high-voltage shield 17.

[0047] In this way, by suppressing the rise in the electric field between the potential fixing plate 20 or high-voltage shield 17 and the outermost part 131 of the primary coil 13, it is possible to prevent the occurrence of discharge between the outermost part 131 of the primary coil 13 and the potential fixing plate 20 or high-voltage shield 17. This improves the insulation performance of the gas-insulated instrument transformer 1.

[0048] Furthermore, the thickness of the second insulator 22 and the thickness of the first insulator 21 are different. Therefore, even if the size of the gap between the outermost part 131 of the primary coil 13 and the potential fixing plate 20 and the high-voltage shield 17 are different, it is possible to properly fill the gap.

[0049] [Embodiment 2] Next, the gas-insulated instrument transformer 1A according to Embodiment 2 of this disclosure will be described with reference to Figure 6. For the sake of convenience of explanation, components having the same function as those described in Embodiment 1 will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0050] Figure 6 is a schematic cross-sectional view of the area around the first insulator 21 of the gas-insulated instrument transformer 1A. As shown in Figure 6, the gas-insulated instrument transformer 1A of Embodiment 2 differs from the gas-insulated instrument transformer 1 of Embodiment 1 in that it has a first insulator 21 but does not have a second insulator 22.

[0051] The first insulator 21, similar to Embodiment 1, is positioned between the outermost periphery 131 of the primary coil 13 and the potential fixing plate 20, and is made of flexible rubber. The first insulator 21 is tightened by the potential fixing plate 20 and deformed to fit the potential fixing plate 20.

[0052] The first insulator 21 fills the gap between the outermost part 131 of the primary coil 13 and the potential fixing plate 20, thereby preventing discharge and improving the insulation performance of the gas-insulated instrument transformer 1A.

[0053] [Embodiment 3] Next, the gas-insulated instrument transformer 1B according to Embodiment 3 of this disclosure will be described with reference to Figure 7. For the sake of convenience of explanation, components having the same function as those described in Embodiment 1 will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0054] Figure 7 is a schematic cross-sectional view of the area around the second insulator 22 of the gas-insulated instrument transformer 1B. As shown in Figure 7, the gas-insulated instrument transformer 1B of Embodiment 3 differs from the gas-insulated instrument transformer 1 of Embodiment 1 in that it has a second insulator 22 but does not have a first insulator 21.

[0055] The second insulator 22, similar to Embodiment 1, is positioned between the outermost periphery 131 of the primary coil 13 and the high-voltage shield 17, and is made of flexible rubber. The second insulator 22 is tightened by the high-voltage shield 17 and deformed to fit the high-voltage shield 17.

[0056] The second insulator 22 fills the gap between the outermost part 131 of the primary coil 13 and the high-voltage shield 17, thereby preventing discharge and improving the insulation performance of the gas-insulated instrument transformer 1B.

[0057] [Embodiment 4] Next, the gas-insulated instrument transformer 1C according to Embodiment 4 of this disclosure will be described with reference to Figure 8. For the sake of convenience of explanation, components having the same function as those described in Embodiment 1 will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0058] The gas-insulated instrument transformer 1C of Embodiment 4 differs from the gas-insulated instrument transformer 1 of Embodiment 1 in that a third insulator 23 is provided instead of the first insulator 21 and the second insulator 22.

[0059] The third insulator 23 is an insulator formed by integrally molding the first insulator 21 and the second insulator 22. The third insulator 23 is positioned between the outermost periphery 131 of the primary coil 13 and the potential fixing plate 20 and the high-voltage shield 17.

[0060] The third insulator 23 is a flexible insulator. The third insulator 23 is made of, for example, flexible rubber. The thickness of the third insulator 23 is uniform. However, the thickness of the third insulator 23 may be set to different thicknesses in different parts, depending on the size of the gap between the outermost part 131 of the primary coil 13 and the potential fixing plate 20 and the high-voltage shield 17.

[0061] The gas-insulated instrument transformer 1C of Embodiment 4 described above can also obtain the same effects as the gas-insulated instrument transformer 1 of Embodiment 1. Specifically, the third insulator 23 fills the gap between the outermost part 131 of the primary coil 13 and the potential fixing plate 20, and the gap between the outermost part 131 of the primary coil 13 and the high-voltage shield 17, thereby preventing the occurrence of discharge. This improves the insulation performance of the gas-insulated instrument transformer 1C.

[0062] In particular, since only a third insulator 23 of uniform thickness needs to be placed between the outermost periphery 131 of the primary coil 13 and the potential fixing plate 20 and high-voltage shield 17, positioning can be performed more easily and a simpler configuration can be achieved compared to the case where the first insulator 21 and the second insulator 22 are placed.

[0063] [Other Embodiments] In the gas-insulated instrument transformer 1 of the embodiment 1 described above, the thickness of the first insulator 21 and the thickness of the second insulator 22 are different from each other, but the invention is not limited to this, and the thickness of the first insulator 21 and the thickness of the second insulator 22 may be the same.

[0064] Furthermore, in the gas-insulated instrument transformer 1 of the above-described embodiment 1, the cross-sectional shapes of the first insulator 21 and the second insulator 22 are rectangular, but are not limited to this, and may be circular or elliptical, for example.

[0065] This disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of Symbols]

[0066] 1, 1A, 1B, 1C Gas-insulated instrument transformers 11 cores 13 Primary coil 15 Secondary coil 17 High-pressure shield 20 Potential fixing plate 21 First insulator 22 Second insulator 23 Third insulator 131 Outermost part

Claims

1. A gas-insulated instrument transformer having a container filled with insulating gas, The core and A secondary coil wound around the aforementioned core, The primary coil is wound around the outside of the secondary coil, A potential fixing plate is positioned outside the primary coil, A high-voltage shield attached to the outer circumference of the aforementioned potential fixing plate, At least one of a flexible first insulator disposed between the outermost part of the primary coil and the potential fixing plate, and a flexible second insulator disposed between the outermost part of the primary coil and the high-voltage shield, A gas-insulated instrument transformer equipped with the following features.

2. The gas-insulated instrument transformer according to claim 1, wherein the first insulator or the second insulator is rubber.

3. The gas-insulated instrument transformer according to claim 1 or 2, wherein the first insulator is tightened by the potential fixing plate and deformed to fit the potential fixing plate.

4. The gas-insulated instrument transformer according to claim 1 or 2, wherein the second insulator is tightened by the high-voltage shield and deformed to fit the high-voltage shield.

5. The invention comprises the first insulator and the second insulator, The gas-insulated instrument transformer according to claim 1 or 2, wherein the first insulator and the second insulator are integrally molded.

6. The invention comprises the first insulator and the second insulator, The gas-insulated instrument transformer according to claim 1 or 2, wherein the Young's modulus and thickness of the first insulator and the Young's modulus and thickness of the second insulator are different from each other.

Images