Insulation evaluation device

Abstract

The objective is to suppress fluctuations at the interface between insulating oil and aqueous solution, thereby causing dielectric breakdown in the area where insulation properties are to be evaluated, and to easily ensure the quality of evaluation related to the insulation properties of windings. [Solution] The winding insulation performance evaluation device comprises a glycerin aqueous solution stored in a container, an insulating oil having a specific gravity lower than the glycerin aqueous solution and stored on top of the glycerin aqueous solution in the container, and a resin plate having a specific gravity intermediate between the glycerin aqueous solution and the insulating oil, and positioned at the interface between the glycerin aqueous solution and the insulating oil. The part of the winding to be evaluated is immersed in the glycerin aqueous solution through the resin plate, and the part of the winding above the part to be evaluated is immersed in the insulating oil.

Description

Technical Field

[0001] The present invention relates to an insulation evaluation device for evaluating the insulation of windings.

Background Art

[0002] Patent Document 1 discloses an electrical breakdown test device (insulation evaluation device) for a power cable. In the breakdown test device disclosed in Patent Document 1, a lower insulating oil having a specific gravity greater than that of water, water disposed above the lower insulating oil, and an upper insulating oil disposed above the water and having a specific gravity smaller than that of water are arranged around the power cable.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the breakdown test device disclosed in Patent Document 1, an alternating voltage is applied to the power cable during the test. However, when the applied voltage is increased, fluctuations occur at the interface between the insulating oil and water, and there is a risk that a part that is not the part where the insulation is originally intended to be evaluated will be broken down. Such a phenomenon may also occur when the breakdown test device disclosed in Patent Document 1 is applied to the insulation evaluation of windings used in a motor of an electric vehicle.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to suppress fluctuations at the interface between an aqueous solution and an insulating oil, breakdown the part where the insulation is originally intended to be evaluated, and easily ensure the evaluation quality related to the insulation evaluation of the winding.

Means for Solving the Problems

[0006] To solve the aforementioned problems, the present invention provides an insulation performance evaluation device for evaluating the insulation performance of a winding, comprising: an aqueous glycerin solution stored in a container; an insulating oil having a specific gravity lower than the aqueous glycerin solution and stored on top of the aqueous glycerin solution in the container; and a resin plate having a specific gravity intermediate between the aqueous glycerin solution and the insulating oil, and positioned at the interface between the aqueous glycerin solution and the insulating oil, wherein the portion of the winding to be evaluated is immersed in the aqueous glycerin solution through the resin plate, and the portion of the winding above the portion to be evaluated is immersed in the insulating oil. [Effects of the Invention]

[0007] According to the present invention, fluctuations at the interface between the aqueous solution and the insulating oil are suppressed, causing dielectric breakdown in the area where the insulating properties are to be evaluated, thereby easily ensuring the evaluation quality related to the insulating properties of windings. [Brief explanation of the drawing]

[0008] [Figure 1] A diagram illustrating the configuration of the insulation performance evaluation apparatus of this embodiment. [Figure 2] A perspective view illustrating the winding shown in Figure 1. [Figure 3] A plan view illustrating the resin plate shown in Figure 1. [Figure 4] A diagram illustrating a conventional insulation performance evaluation device. [Figure 5] Another diagram illustrating a conventional insulation performance evaluation device. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. Components denoted by the same reference numerals in each embodiment are similar in each embodiment unless otherwise specified, and their descriptions will be omitted.

[0010] Figure 1 is a diagram illustrating the configuration of the insulation performance evaluation device 10 of this embodiment. Figure 2 is a perspective view illustrating the winding 1 shown in Figure 1. Figure 3 is a plan view illustrating the resin plate 20 shown in Figure 1. Note that in Figure 1, in order to clearly show the shape of the winding 1, the resin plate 20 is shown in cross-section along the longitudinal direction of the winding 1 (perpendicular to the plane of the paper).

[0011] The insulation performance evaluation device 10 is a device for evaluating the insulation performance of the winding 1. The winding 1 is, for example, a winding used in a motor mounted on an electric vehicle. As shown in Figure 2, the winding 1 is formed by covering a conductor 2 such as copper or aluminum with an insulating film 3 such as enamel. The winding 1 may be a winding with a dielectric breakdown voltage of 10kV to 20kV. The winding 1 may be a high-voltage winding with a dielectric breakdown voltage of 20kV or more. The winding 1 may be made up of a rectangular cross-sectional wire as shown in Figure 2, or it may be made up of a circular cross-sectional wire.

[0012] As shown in Figure 1, the insulation performance evaluation device 10 comprises a glycerin aqueous solution 13 stored in a container 11 and insulating oil 12 stored on top of the glycerin aqueous solution 13 in the container 11.

[0013] Since winding 1 is a high-voltage winding, it is not possible to measure the dielectric breakdown voltage of winding 1 in the atmosphere in order to evaluate its insulation properties. For this reason, the insulation performance evaluation device 10 immerses the part of winding 1 to be evaluated, which is the part of winding 1 to be measured for dielectric breakdown voltage, in a glycerin aqueous solution 13 to measure the dielectric breakdown voltage of winding 1. Furthermore, in order to prevent creepage discharge that discharges from the surface of winding 1 immersed in the glycerin aqueous solution 13 towards the atmosphere (upward) along winding 1, the insulation performance evaluation device 10 places insulating oil 12 on top of the glycerin aqueous solution 13.

[0014] The insulating oil 12 has a specific gravity lower than the glycerin aqueous solution 13 and a dielectric breakdown voltage higher than the insulating film 3 of the winding 1. The type of insulating oil 12 is not particularly limited as long as it has a specific gravity lower than the glycerin aqueous solution 13 and a dielectric breakdown voltage higher than the insulating film 3 of the winding 1. Examples of the type of insulating oil 12 include mineral oil, alkylbenzene oil, or silicone oil from among the JIS standard types 1 to 7 electrical insulating oils (JIS C2320). The glycerin aqueous solution 13 is electrically connected to the earth 14.

[0015] When measuring the dielectric breakdown voltage of winding 1, the winding 1 is positioned with its evaluation portion 4 bent so that one end 5 and the other end 6 of the winding 1 are exposed above the insulating oil 12. For example, as shown in Figure 1, winding 1 is bent into a U-shape so that it bends 180 degrees at the evaluation portion 4. The winding 1 is positioned so that the evaluation portion 4 is immersed in the glycerin aqueous solution 13, the portion above the evaluation portion 4 is immersed in the insulating oil 12, and one end 5 and the other end 6 are exposed above the insulating oil 12.

[0016] An AC power supply (not shown) is connected to one end 5 and the other end 6 of the winding 1 arranged in this manner. When measuring the dielectric breakdown voltage of winding 1, an AC voltage is applied to one end 5 and the other end 6 of winding 1. The AC voltage applied to winding 1 is increased until winding 1 undergoes dielectric breakdown, or more precisely, until the insulating film 3 of winding 1 undergoes dielectric breakdown.

[0017] Furthermore, the insulation performance evaluation device 10 includes a resin plate 20 positioned at the interface between the glycerin aqueous solution 13 and the insulating oil 12. The resin plate 20 is positioned on the interface in a manner aligned with the interface between the glycerin aqueous solution 13 and the insulating oil 12. The evaluation target portion 4 of the winding 1 is immersed in the glycerin aqueous solution 13, passing through the resin plate 20.

[0018] The resin plate 20 has a specific gravity intermediate between that of the glycerin aqueous solution 13 and the insulating oil 12, and has a breakdown voltage higher than that of the insulating film 3 of the winding 1. The resin material forming the resin plate 20 is not particularly limited as long as it is an insulating material having a specific gravity intermediate between that of the glycerin aqueous solution 13 and the insulating oil 12. For example, the density of the resin plate 20 is preferably the intermediate density (0.87 g / mL to 1.23 g / mL) between that of the glycerin aqueous solution 13 and the insulating oil 12. The breakdown voltage of the resin plate 20 is preferably 10 kV or more (the volume resistivity is 10 14 Ω·cm or more). Examples of the material forming the resin plate 20 include polypropylene-based resin materials. Further, the resin plate 20 has a certain degree of rigidity so as not to be deflected by the fluctuation of the interface between the glycerin aqueous solution 13 and the insulating oil 12.

[0019] The resin plate 20 is formed in a plate shape without corners in plan view so that electric field concentration does not occur. The resin plate 20 may be formed, for example, in a disc shape, an elliptical plate shape, or a corrugated plate shape. That is, the outer edge portion 21 of the resin plate 20 forms a curved shape in plan view so that electric field concentration does not occur. Further, the resin plate 20 is formed in a plate shape with rounded corners in side view so that electric field concentration does not occur.

[0020] The resin plate 20 shown in FIG. 3 is in a disc shape, and the diameter L1 is preferably 50 mm or more. When the breakdown voltage of the winding 1 exceeds 40 kV, the diameter L1 of the resin plate 20 is preferably 70 mm or more. The plate thickness of the resin plate 20 is preferably 3 mm or more. The plate thickness of the resin plate 20 is preferably 5 mm or more and 10 mm or less.

[0021] Further, the resin plate 20 has through holes 22 and 23 through which the winding 1 passes. The through holes 22 and 23 include a first through hole 22 passing through a first portion 7 from one end portion 5 of the winding 1 to the evaluation target portion 4, and a second through hole 23 passing through a second portion 8 from the other end portion 6 of the winding 1 to the evaluation target portion 4. The through holes 22 and 23 are defined by inner edge portions 24 and 25 of the resin plate 20. The inner edge portions 24 and 25 are curved in a plan view so that no electric field concentration occurs. The inner edge portions 24 and 25 include a first inner edge portion 24 defining the first through hole 22 and a second inner edge portion 25 defining the second through hole 23.

[0022] Gaps 26 and 27 are provided between the winding 1 passing through the through holes 22 and 23 and the inner edge portions 24 and 25 of the resin plate 20. The size of the gaps 26 and 27, specifically, the distance L2 from the surface of the winding 1 to the inner edge portions 24 and 25 is preferably 0.4 mm or more and 1 mm or less. The gaps 26 and 27 include a first gap 26 provided between the first portion 7 of the winding 1 and the first inner edge portion 24 of the resin plate 20, and a second gap 27 provided between the second portion 8 of the winding 1 and the second inner edge portion 25 of the resin plate 20.

[0023] The operation and effect of the insulation evaluation apparatus 10 of the present embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a diagram for explaining a conventional insulation evaluation apparatus 10A. FIG. 5 is another diagram for explaining the conventional insulation evaluation apparatus 10A.

[0024] A conventional insulation performance evaluation device 10A for evaluating the insulation performance of winding 1 comprises, as shown in Figure 4, a glycerin aqueous solution 13 stored in a container 11 and insulating oil 12 stored on top of the glycerin aqueous solution 13 in the container 11. In the conventional insulation performance evaluation device 10A, the evaluation target part 4 of winding 1 is immersed in the glycerin aqueous solution 13, an AC voltage is applied to winding 1, and the applied voltage is increased. When the applied voltage is increased, fluctuations occur at the interface between the glycerin aqueous solution 13 and the insulating oil 12 in the conventional insulation performance evaluation device 10A. When these interface fluctuations occur, electric field concentration is more likely to occur, and dielectric breakdown occurs not in the evaluation target part 4, which is the part whose insulation performance is to be evaluated, but in the part that comes into contact with the fluctuating interface. In particular, when evaluating a high-voltage winding with a dielectric breakdown voltage of 20kV or more as winding 1, the occurrence of these interface fluctuations is significant, making it difficult to properly evaluate the evaluation target part 4 of winding 1 by causing dielectric breakdown.

[0025] To avoid this phenomenon, for example, if we wait until the fluctuations at the interface subside and the insulating oil 12 and glycerin aqueous solution 13 are completely separated, this waiting time will increase the evaluation time. Also, as shown in Figure 5, if we immerse the winding 1 deep in the glycerin aqueous solution 13 to avoid the effects of the fluctuations at the interface, we need to make the winding 1 longer, which increases the amount of winding 1 used. Furthermore, if we make the insulating film 3 of the winding 1 thicker, surface discharge is more likely to occur, so we need to increase the height of the insulating oil 12, which increases the amount of insulating oil 12 used.

[0026] In contrast, the insulation performance evaluation device 10 of this embodiment is an insulation performance evaluation device for evaluating the insulation performance of a winding 1, and comprises a glycerin aqueous solution 13 stored in a container 11, an insulating oil 12 having a specific gravity lower than the glycerin aqueous solution 13 and stored on top of the glycerin aqueous solution 13 in the container 11, and a resin plate 20 having a specific gravity intermediate between the glycerin aqueous solution 13 and the insulating oil 12 and positioned at the interface between the glycerin aqueous solution 13 and the insulating oil 12. The part of the winding 1 to be evaluated 4 is immersed in the glycerin aqueous solution 13 through the resin plate 20. The part of the winding 1 above the part of the winding 1 to be evaluated 4 is immersed in the insulating oil 12.

[0027] As a result, even when the voltage applied to the winding 1 is increased, the insulation performance evaluation device 10 can easily suppress fluctuations at the interface between the glycerin aqueous solution 13 and the insulating oil 12, as the resin plate 20 acts as a vibration damping and cushioning material. Therefore, the insulation performance evaluation device 10 can easily cause dielectric breakdown in the evaluation target part 4, which is the part for which the insulation performance is to be evaluated, without increasing the evaluation time or increasing the amount of winding 1 and insulating oil 12 used. Furthermore, the insulation performance evaluation device 10 does not need to use three liquid phases by adding insulating oil below the glycerin aqueous solution 13, as in Patent Document 1. Thus, the insulation performance evaluation device 10 can easily ensure the evaluation quality related to the insulation performance evaluation of the winding 1 by suppressing fluctuations at the interface between the glycerin aqueous solution 13 and the insulating oil 12 and causing dielectric breakdown in the part for which the insulation performance is to be evaluated.

[0028] Furthermore, the insulation evaluation device 10 of this embodiment has a resin plate 20 and through holes 22 and 23 through which the winding 1 passes. Gaps 26 and 27 are provided between the winding 1 passing through the through holes 22 and 23 and the inner edges 24 and 25 of the resin plate 20 that define the through holes 22 and 23.

[0029] As a result, the insulation performance evaluation device 10 can easily position the resin plate 20 at the interface between the glycerin aqueous solution 13 and the insulating oil 12 simply by inserting the through holes 22 and 23 of the resin plate 20 into the winding 1 which is immersed in the glycerin aqueous solution 13 and the insulating oil 12. In other words, if there are no gaps 26 and 27 in the resin plate 20, it is necessary to manually move the resin plate 20 to the interface after inserting it into the winding 1 to position it. In this case, the time required to position the resin plate 20 increases the evaluation time, or the resin plate 20 cannot be positioned on the interface in an orientation along the interface, making it difficult to stably suppress fluctuations at the interface. Since the resin plate 20 is provided with gaps 26 and 27, the insulation performance evaluation device 10 can easily position the resin plate 20 at the interface between the glycerin aqueous solution 13 and the insulating oil 12. Furthermore, since the insulation performance evaluation device 10 has gaps 26 and 27 in the resin plate 20, it is possible to suppress the occurrence of electric field concentration near the through holes 22 and 23. Therefore, the insulation performance evaluation device 10 can easily suppress fluctuations at the interface between the glycerin aqueous solution 13 and the insulating oil 12, causing dielectric breakdown in the part where the insulation performance is to be evaluated, and thus easily ensuring the evaluation quality related to the insulation performance evaluation of the winding 1.

[0030] Furthermore, in the insulation performance evaluation device 10 of this embodiment, the winding 1 is arranged with the evaluation target portion 4 bent so that one end 5 and the other end 6 of the winding 1 are exposed above the insulating oil 12. The through holes 22 and 23 include a first through hole 22 through which the first portion 7 from one end 5 of the winding 1 to the evaluation target portion 4 passes, and a second through hole 23 through which the second portion 8 from the other end 6 of the winding 1 to the evaluation target portion 4 passes.

[0031] As a result, the insulation performance evaluation device 10 can evaluate the insulation performance of the winding 1 when the insulating coating 3 of the winding 1 in the evaluation target part 4 is thinned, and can provide a resin plate 20 that is suitable for the winding 1 in this state. Therefore, the insulation performance evaluation device 10 can prevent overestimating the insulation performance of the winding 1. Thus, the insulation performance evaluation device 10 can easily suppress fluctuations at the interface between the glycerin aqueous solution 13 and the insulating oil 12, causing dielectric breakdown in the part where the insulation performance is to be evaluated, and can easily and reliably ensure the evaluation quality related to the insulation performance evaluation of the winding 1.

[0032] Furthermore, in the insulation performance evaluation device 10 of this embodiment, the inner edges 24 and 25 of the resin plate 20 are curved.

[0033] As a result, the insulation performance evaluation device 10 can suppress the occurrence of electric field concentration near the inner edges 24 and 25 of the resin plate 20. Therefore, the insulation performance evaluation device 10 can suppress fluctuations at the interface between the glycerin aqueous solution 13 and the insulating oil 12, reliably causing dielectric breakdown in the area where the insulation performance is to be evaluated, and thus easily and reliably ensuring the evaluation quality related to the insulation performance evaluation of the winding 1.

[0034] Furthermore, in the insulation performance evaluation device 10 of this embodiment, the outer edge 21 of the resin plate 20 is curved.

[0035] As a result, the insulation performance evaluation device 10 can suppress the occurrence of electric field concentration near the outer edge 21 of the resin plate 20. Therefore, the insulation performance evaluation device 10 can suppress fluctuations at the interface between the glycerin aqueous solution 13 and the insulating oil 12, reliably causing dielectric breakdown in the area where the insulation performance is to be evaluated, and easily and reliably ensuring the evaluation quality related to the insulation performance evaluation of the winding 1.

[0036] Although embodiments of the present invention have been described in detail above, the present invention is not limited to each embodiment, and various modifications can be made without departing from the spirit of the invention. The present invention can be modified by adding components of one embodiment to components of another embodiment, replacing components of one embodiment with components of another embodiment, or deleting parts of components of one embodiment. [Explanation of Symbols]

[0037] 1...Winding, 2...Conductor, 3...Insulating coating, 4...Part to be evaluated, 5...One end, 6...Other end, 7...First part, 8...Second part, 10...Insulation evaluation device, 10A...Conventional insulation evaluation device, 11...Container, 12...Insulating oil, 13...Glycerin aqueous solution, 14...Ground, 20...Resin plate, 21...Outer edge, 22...First through hole (through hole), 23...Second through hole (through hole), 24...First inner edge (inner edge), 25...Second inner edge (inner edge), 26...First gap (gap), 27...Second gap (gap)

Claims

1. An insulation evaluation device for evaluating the insulation properties of a winding, The glycerin aqueous solution stored in the container, An insulating oil having a specific gravity lower than the glycerin aqueous solution, stored on top of the glycerin aqueous solution in the container, The system comprises a resin plate having a specific gravity intermediate between the glycerin aqueous solution and the insulating oil, and disposed at the interface between the glycerin aqueous solution and the insulating oil. The part of the winding to be evaluated is immersed in the glycerin aqueous solution, penetrating the resin plate. The portion of the winding above the evaluation target is immersed in the insulating oil. An insulating properties evaluation apparatus characterized by the following:

2. The resin plate has through holes through which the windings pass, A gap is provided between the winding passing through the through hole and the inner edge of the resin plate defining the through hole. An insulating properties evaluation apparatus as described in claim 1.

3. The winding is arranged with the part to be evaluated bent such that one end and the other end of the winding are exposed above the insulating oil. The through-hole includes a first through-hole through which a first portion of the winding passes from one end to the evaluation target, and a second through-hole through which a second portion of the winding passes from the other end to the evaluation target. An insulating properties evaluation apparatus as described in claim 2.

4. The inner edge of the resin plate is curved. An insulating performance evaluation apparatus as described in claim 3.

5. The outer edge of the resin plate is curved. An insulating performance evaluation apparatus as described in feature 4.

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