Method and device for supporting evaluation of insulation deterioration as well as method for creating insulation deterioration pattern management diagram

Abstract

To appropriately evaluate insulation deterioration of a target apparatus subjected to vacuum pressure impregnation processing.SOLUTION: Provided is an evaluation support method for allowing evaluation of insulation deterioration of a target apparatus subjected to vacuum pressure impregnation processing, the method including determining an index representing the relationship between a capacitance C0 when the vacuum pressure impregnation processing is executed for the first time and a capacitance C when the vacuum pressure impregnation processing is executed during a repair period. By using the capacitance C0 and an amount ΔC of change of the capacitance when the vacuum pressure impregnation processing is executed during the repair period relative to the capacitance C0, a capacitance reduction rate represented by the formula including ΔC / C0 is defined as the index.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a technology used to manage the insulation of target equipment that has been subjected to vacuum pressure impregnation treatment, and relates to an evaluation support method and device that enable evaluation of insulation deterioration, as well as a method for creating an insulation deterioration pattern control chart. [Background technology]

[0002] As an insulation measure for devices such as electric motors, a vacuum pressure impregnation (VPI) process is sometimes used to impregnate voids in the insulation layer with resin. Patent Document 1 discloses that the degree of vacuum pressure impregnation when filling the insulating layer of a rotating machine coil with a thermosetting resin is detected as the change in capacitance per unit time within the insulating layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Jitszen No. 62-149263 Summary of the Invention [Problem to be solved by the invention]

[0004] As described in Patent Document 1, there is a method for evaluating the degree of vacuum-pressure impregnation during the vacuum-pressure impregnation process, but there is no established method for evaluating the insulation deterioration of the target equipment that has been subjected to the vacuum-pressure impregnation process.

[0005] The present invention has been made in view of the above-mentioned points, and an object of the present invention is to enable accurate evaluation of insulation deterioration of a target device that has been subjected to vacuum pressure impregnation treatment. [Means for solving the problem]

[0006] The insulation deterioration evaluation support method of the present invention is an evaluation support method that enables evaluation of insulation deterioration of target equipment that has been subjected to vacuum pressure impregnation treatment, and is characterized by having a procedure for determining an index that represents the relationship between the capacitance when vacuum pressure impregnation treatment is performed for the first time and the capacitance when vacuum pressure impregnation treatment is performed during repair. [Effects of the Invention]

[0007] According to the present invention, it is possible to accurately evaluate the insulation deterioration of a target device that has been subjected to a vacuum pressure impregnation treatment. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a flowchart showing the flow of a vacuum pressure impregnation process. [Figure 2] FIG. 1 is a diagram showing a configuration example of a vacuum pressure impregnation device. [Figure 3] FIG. 4 is a diagram illustrating an insulating layer of the stator. [Figure 4] 10A and 10B are diagrams illustrating an example of the relationship between each step of a vacuum pressure impregnation process and capacitance. [Figure 5] FIG. 10 is a diagram illustrating an example of a time series change in capacitance reduction rate. [Figure 6] FIG. 10 is a diagram showing an example of an insulation deterioration pattern control chart. [Figure 7] FIG. 2 illustrates an example of a functional configuration of an evaluation support device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. An outline of the vacuum pressure impregnation process (hereinafter referred to as VPI (Vacuum Pressure Impregnated)) will be described with reference to FIGS. FIG. 2 is a diagram showing an example of the configuration of a vacuum pressure impregnation apparatus 100 for carrying out VPI. The vacuum pressure impregnation apparatus 100 includes an impregnation tank (vacuum pressure impregnation furnace) 101, which is a pressure vessel for placing the target device. In this embodiment, the target device is a stator 1 of an electric motor (a stator core 2 to which a coil 3 is assembled), and the stator core 2 and the coil 3 are integrated with resin, which serves as an insulating material. Note that, for example, in the case of a large electric motor, the coil 3 alone may be the target device. A vacuum pump 102 for evacuation and a compressor 103 for pressurizing are connected to the impregnation tank 101. Also, a resin supply source (not shown) for injecting resin is connected to the impregnation tank 101.

[0010] FIG. 1 is a flowchart showing the flow of VPI. In step S1, the stator 1, which is the target device, is placed in the impregnation tank 101. In step S2, the vacuum pump 102 is used to create a vacuum inside the impregnation tank 101, and resin is injected from the resin supply source into the impregnation tank 101. For example, it takes about three hours to maintain the vacuum and about two hours to inject the resin. In step S3, the impregnation tank 101 is left to degas while maintaining a vacuum state inside the tank 101. For example, it takes about 15 hours to degas. In step S4, the inside of the impregnation tank 101 is pressurized with dry air using the compressor 103, and finally the pressure is released, which takes, for example, about 4 to 6 hours. In step S5, the stator 1 is removed from the impregnation tank 101. In step S6, the stator 1 is placed in a drying oven (not shown), heated to dry, and then cooled to the same temperature as the outside air. The drying process completely hardens the resin, improving insulation, strength, and cooling efficiency. For example, it takes about 2 to 3 hours to prepare the stator before placing it in the drying oven, and it takes more than 12 hours to dry it in the oven and cool it down.

[0011] Figure 3 is a diagram for explaining the insulating layer of the stator 1, where (a) is a schematic cross-sectional view of a part of the stator 1 (one groove 4 provided on the inner surface of the stator core 2), and (b) is an enlarged schematic view of part A of (a). As shown in Figure 3(a), a coil 3 wound with insulating tape 5 is fitted into each groove (slot) 4 provided on the inner peripheral surface of the stator core 2. Then, to prevent the coil 3 from falling off, a wedge (not shown) for fixing the coil is driven into the groove 4. In this way, an insulating layer is formed between the coil 3 and the stator core 2, with the wound portion of the insulating tape 5 serving as the main insulating layer.

[0012] As shown in the left diagram of Figure 3(b), when the insulating tape 5 is simply wound around the coil 3, there is a gap inside the insulating tape 5 in the insulating layer, and a gap may also form between the coil 3 around which the insulating tape 5 is wound and the stator core 2, resulting in a state close to air insulation.

[0013] By applying VPI, the state changes from the left side of Figure 3(b) to the center side of Figure 3(b), where resin penetrates into the gaps and cracks in the insulating layer, resulting in a resin-insulated state. In this way, the relative permittivity of the insulating layer changes depending on the amount of resin that penetrates and is held in the insulating layer, and the capacitance also changes. The capacitance C is calculated by dividing the dielectric constant of a vacuum (ε0) by the dielectric constant of a solid insulator (ε s , conductor area S, distance between conductors L, C=ε0ε s If there is no change in the conductor area S or the distance between the conductors L, the capacitance C is expressed as the relative permittivity ε of the solid insulator. s The capacitance of a new coil or coil that has undergone vacuum pressure impregnation treatment is greater than the capacitance in a state close to air insulation (left diagram in Figure 3(b)).

[0014] Furthermore, as shown in the right diagram of Figure 3(b), operation of the motor can cause voids (air bubbles) 6 to form in the insulation layer, or gaps 7 to form between the coil 3 and the stator core 2, which can lead to the progression of insulation deterioration. When voids 6 or gaps 7 exist, the capacitance is smaller than the capacitance when vacuum pressure impregnation processing is performed when a new coil is manufactured or when the coil is rewound (center diagram of Figure 3(b)).

[0015] Here, as an insulation measure for the stator 1 of the electric motor, in addition to applying VPI for the first time (when manufacturing a new motor or when rewinding the coil), VPI may also be applied when repairs are made that require insulation recovery due to operation. Figure 4 shows an example of the relationship between each VPI process and capacitance. The solid characteristic line shows the change in capacitance when VPI is applied for the first time. The dotted characteristic line shows the change in capacitance when VPI is applied during repair. When VPI is applied for the first time, the capacitance at the start is close to that of air insulation (left diagram in Figure 3(b)). Then, as the process moves from the vacuum and resin injection process to the pressure process, the capacitance initially tends to increase, then decreases in the pressure release process, and after the drying process, reaches capacitance C0. This capacitance C0 when VPI is applied for the first time is called the initial value C0.

[0016] When VPI is applied during repair, the capacitance at the start is greater than the capacitance at the start of the first VPI (capacitance in a state close to air insulation). This is because resin from the first VPI remains when VPI is applied during repair. In this case too, when moving from the vacuum and resin injection process to the pressure process, the capacitance initially tends to increase, then decreases during the pressure release process, and after the drying process, becomes capacitance C (C1, C2). The capacitance C when VPI is applied during this repair is called the capacitance C during repair.

[0017] Here, the amount of change in capacitance C at the time of repair relative to the initial value C0 is assumed to be ΔC=C0−C. In Repair 1, ΔC≒0 (C0≒C1), and the capacitance C1 at the time of repair is the same as the initial value C0. In this case, the insulation has been sufficiently restored and there is no irreversible insulation deterioration. On the other hand, in repair 2, ΔC>0, and the capacitance C2 at the time of repair is smaller than the initial value C0. In this case, there are voids 6 and gaps 7 in the VPI where resin penetration is not expected, and it can be said that there is irreparable insulation deterioration. The more voids 6 and gaps 7 in the VPI where resin penetration is not expected, the smaller the capacitance C at the time of repair and the larger ΔC tends to be.

[0018] In this way, by obtaining an index that shows the relationship between the initial value C0 and the capacitance C at the time of repair, it becomes possible to accurately evaluate the insulation deterioration of the target equipment (stator 1) that has undergone VPI. In this case, by using the capacitance after the drying process as the initial value C0 and the capacitance C at the time of repair, it becomes possible to eliminate the effects of ambient temperature, humidity, and the state of surface contamination of the insulator, enabling an accurate and uniform evaluation of insulation deterioration.

[0019] In this embodiment, the initial value C0 and the change ΔC (=C0-C) in the capacitance C at the time of repair relative to the initial value C0 are used as an index representing the relationship between the initial value C0 and the capacitance C at the time of repair. Then, the capacitance reduction rate %Sy is defined as shown in formula (1). %Sy=(ΔC / C0)×100 (1)

[0020] An example of a method for evaluating insulation deterioration of a target device (stator 1) based on the capacitance reduction rate %Sy will be described below with reference to Fig. 5 and Fig. 6. Fig. 5 is a diagram showing an example of time-series changes in the capacitance reduction rate %Sy. Fig. 6 is a diagram showing an example of an insulation deterioration pattern control chart. To evaluate the insulation deterioration of the stator 1, area management is performed, which captures the long-term time series change in the capacitance reduction rate %Sy, and term management is performed, which captures the short-term time series change in the capacitance reduction rate %Sy during the actual operating period.

[0021] (Area Management) In area management, the time series change of the capacitance reduction rate %Sy is calculated for a predetermined period N starting from the timing when VPI was first applied. The predetermined period N is the design life of the motor set by the manufacturer. Timing T0 in Figure 5 is the timing when VPI is performed for the first time. At timing T0, the capacitance reduction rate %Sy = 0. Then, assume that VPI is performed during repair at timing T1. This gives the capacitance C at the time of repair, so the capacitance reduction rate %Sy can be calculated using equation (1). By obtaining a characteristic line that passes through the capacitance reduction rate %Sy = 0 and the capacitance reduction rate %Sy = P1 calculated here, characteristic line 501 can be obtained that represents the time series change in the capacitance reduction rate %Sy over a specified period N.

[0022] Here, to evaluate insulation deterioration after a predetermined period N has elapsed, areas are set up to be ranked in three stages, "Good," "Needs trend management," and "Needs measures," in order of decreasing capacitance reduction rate %Sy. To enable evaluation based on the angle of inclination θ of characteristic line 501 (hereinafter referred to as the deviation angle), the deviation angle θ is expressed mathematically by equation (2). θ=arctan(%Sy / N) (2) Deviation angle θ and threshold θ that separates the three areas a , θ b The relationship between θ≦θ a :Good, θ a <θ≦θ b :Trend management required, θ>θ b :Measures required Let's say.

[0023] (Term Management) In term management, the time series change of the capacitance reduction rate %Sy' is calculated for an actual operating period n that is shorter than a predetermined period N, starting from the timing when VPI was applied during repair. After VPI is applied during repair (for example, timing T1, capacitance reduction rate P1), the capacitance at that time is obtained after the actual operating period n has elapsed. From this, the capacitance reduction rate %Sy=P2 after the actual operating period n has elapsed can be calculated using equation (1). By obtaining a characteristic line that passes through the capacitance reduction rate %Sy=P1 and the capacitance reduction rate %Sy=P2 calculated here, a characteristic line 502 that represents the time series change in the capacitance reduction rate %Sy' during the actual operating period n can be obtained. The capacitance reduction rate during the actual operating period n is calculated as the amount of change ΔP=P1-P2. The reduction rate %Sy' is expressed as in equation (3). %Sy´=(ΔP / P1)×100 (3)

[0024] Here again, in order to enable evaluation using the angle of inclination (hereinafter referred to as the deviation angle) θ' of characteristic line 502, the deviation angle θ' is expressed mathematically by equation (4). θ´=arctan(%Sy´ / n) ···(4) Influenced by operation and the environment, insulation deterioration may progress at a rate different from the insulation deterioration due to the expected lifespan over a specified period N. Term management quantifies this short-term fluctuation, and is a technology that can determine the degree of deterioration over the actual operating time and predict the timing of deviation from the area of ​​area management. Here, the threshold value of deviation angle θ' in term management is set to the threshold value θ of deviation angle θ in area management. a , θ b The threshold value of the deviation angle θ' in the term management is set to the same value as the threshold value θ of the deviation angle θ in the area management. a , θ b It may be a different value.

[0025] In the example of Figure 5, in area management, θ≦θ a However, in term management, θ a <θ´≦θ b In other words, during the actual operating period n, the insulation deterioration progresses at a different degree than that expected for the specified period N. In this way, even if the deterioration suddenly changes due to the influence of operation or the environment while the insulation is deteriorating over time, it is possible to determine the change in the degree of the deterioration.

[0026] (Evaluation based on insulation deterioration pattern control chart) As shown in Fig. 6, an insulation deterioration pattern control chart is created in which the deviation angle θ in area management is plotted on the horizontal axis and the deviation angle θ' in term management is plotted on the vertical axis, with regions divided by thresholds. Note that it is also possible to plot the deviation angle θ' in term management on the horizontal axis and the deviation angle θ in area management on the vertical axis. In the example of FIG. 6, in the region 601 (θ≦θ a and θ´≦θ a ) is the "good" region. a and θ a <θ´≦θ b ), region 603(θ a <θ≦θ b and θ a <θ´≦θ b ), region 604(θ a <θ≦θ b and θ´≦θ a ), region 605(θ≦θ a and θ´>θ b ) is the "trend management required" area. a <θ≦θ b and θ´>θ b ), region 607(θ>θ b and θ´>θ b ), region 608(θ>θ b and θ a <θ´≦θ b ), region 609(θ>θ b and θ´≦θ a ) is the "measures required" area. The "measures required" areas are graded by strength, and area 607 is the strongest area (requiring urgent measures), and "rewinding implementation" is deemed appropriate.

[0027] For example, point K1 in Figure 6 is θ≦θ in area management. a However, in term management, θ a <θ´≦θ b and belongs to the "trend management required" area 602. Also, point K2 is in the area management, and θ≦θ a However, in term management, θ´>θ band belongs to the "trend management required" area 605. Also, point K3 is in the term management mode where θ'≦θ a However, in area management, θ>θ b This means that it belongs to the "measures required" area 609. In area 609, "reducing the repair cycle or considering rewinding" is deemed appropriate. In this way, this is a technology that evaluates insulation deterioration by crossing each other's management levels. By using this insulation deterioration pattern control chart, it becomes possible to comprehensively determine the degree of insulation deterioration, the timing and method of repair, based on the deviation angles θ and θ' obtained from area management and term management, respectively. Although there are two threshold values ​​for the deviation angle θ′ in the term management and two threshold values ​​for the deviation angle θ in the area management, the number is not limited to two.

[0028] FIG. 7 shows an example of the functional configuration of an evaluation support device 700 used in the insulation deterioration evaluation support method of the above-described embodiment. The evaluation support device 700 includes an input unit 701 , a calculation unit 702 , a storage unit 703 , and an output unit 704 . The input unit 701 inputs an initial value C0 measured after the first VPI drying process and a capacitance C at the time of repair measured after the VPI drying process at the time of repair. The input unit 701 also inputs a capacitance measured when n operating periods have elapsed since repair.

[0029] When VPI is applied during repair, the calculation unit 702 calculates the characteristic line 501 representing the time series change in the capacitance reduction rate % Sy over a predetermined period N, and also calculates the deviation angle θ in area management. Furthermore, when the actual operating period n has elapsed since the repair, the calculation unit 702 calculates the characteristic line 502 representing the time series change in the capacitance reduction rate % Sy' over the actual operating period n, and also calculates the deviation angle θ' in term management.

[0030] The storage unit 703 stores the initial value C0 input by the input unit 701, the capacitance C at the time of repair, and the deviation angle θ in area management calculated by the calculation unit 702 so that they can be used later. The storage unit 703 also stores data on the insulation deterioration pattern management chart.

[0031] The output unit 704 outputs the various values ​​calculated by the calculation unit 702 and the various data to be stored in the storage unit 703. The output unit 704 displays the various values ​​calculated by the calculation unit 702 and the various data to be stored in the storage unit 703, for example, on a display (not shown), or transmits them to another device. The output unit 704 displays, on a display, the results of applying the points specified by the deviation angles θ and θ' to an insulation deterioration pattern control chart, as shown in Fig. 6, for example. The evaluation support device 700 thus configured is configured by a computer device equipped with, for example, a CPU, a ROM, a RAM, etc., and the functions of each of the units 701 to 704 are realized by the CPU executing a predetermined program stored in, for example, the ROM.

[0032] Although the present invention has been described above with reference to the embodiments, the above embodiments are merely illustrative of specific examples of how the present invention can be implemented, and the technical scope of the present invention should not be construed as being limited by these embodiments. In other words, the present invention can be implemented in various forms without departing from its technical concept or main features. [Explanation of symbols]

[0033] 1: stator, 2: stator core, 3: coil, 4: groove, 5: insulating tape, 100: vacuum pressure impregnation device, 101: impregnation tank, 102: vacuum pump, 103: compressor, 700: evaluation support device, 701: input unit, 702: calculation unit, 703: storage unit, 704: output unit

Claims

1. An evaluation support method for evaluating insulation deterioration of a target device that has been subjected to vacuum pressure impregnation treatment, comprising: A method for supporting evaluation of insulation deterioration, comprising the step of determining an index representing the relationship between the capacitance when vacuum pressure impregnation treatment is performed for the first time and the capacitance when vacuum pressure impregnation treatment is performed during repair.

2. As the index, the capacitance C 0 and the capacitance C 0 The change in capacitance Δ when vacuum pressure impregnation treatment is performed during the repair Using C, ΔC / C 0 The capacitance reduction rate is defined by an equation including The method for supporting evaluation of insulation deterioration according to claim 1 .

3. 3. The method for supporting evaluation of insulation deterioration according to claim 2, wherein the time series change in the capacitance reduction rate is calculated for a predetermined period starting from the timing when the vacuum pressure impregnation treatment is first performed.

4. 4. The method for supporting evaluation of insulation deterioration according to claim 3, further comprising determining a time series change in the capacitance reduction rate during an actual operation period that is shorter than the predetermined period, starting from the timing when the vacuum pressure impregnation treatment is performed during repair.

5. 5. The method for supporting evaluation of insulation deterioration according to claim 4, wherein a threshold value for evaluating insulation deterioration is set for each of an angle of inclination of the characteristic line representing the time-series change in the capacitance reduction rate during the predetermined period and an angle of inclination of the characteristic line representing the time-series change in the capacitance reduction rate during the actual operation period.

6. 6. The method for supporting evaluation of insulation deterioration according to claim 5, wherein an insulation deterioration pattern control chart is created in which the angle of inclination of the characteristic line during the specified period is plotted on one of the vertical axis and the horizontal axis, and the angle of inclination of the characteristic line during the actual operation period is plotted on the other axis, and the regions are divided by the threshold value.

7. 7. The insulation deterioration evaluation support method according to claim 1, wherein the target device is a stator or a coil of an electric motor.

8. An evaluation support device that can evaluate insulation deterioration of a target device that has been subjected to vacuum pressure impregnation treatment, An evaluation support device for insulation deterioration, comprising a means for calculating an index representing the relationship between the capacitance when vacuum pressure impregnation treatment is performed for the first time and the capacitance when vacuum pressure impregnation treatment is performed during repair.

9. Capacitance C when vacuum pressure impregnation treatment is performed for the first time 0 and the capacitance C 0 Using the change in capacitance ΔC when vacuum pressure impregnation treatment is performed during repair, ΔC / C 0 Define the capacitance reduction rate expressed by an equation including a threshold value for evaluating insulation deterioration is set for each of the angle of inclination of a characteristic line representing the time series change in the capacitance reduction rate during a predetermined period starting from the timing when the vacuum pressure impregnation treatment is first performed, and the angle of inclination of a characteristic line representing the time series change in the capacitance reduction rate during an actual operation period that is shorter than the predetermined period starting from the timing when the vacuum pressure impregnation treatment is performed during repair; a method for creating an insulation degradation pattern control chart, the method comprising: plotting the angle of inclination of the characteristic line during the predetermined period on one of the vertical axis and the horizontal axis, and plotting the angle of inclination of the characteristic line during the actual operation period on the other axis, and creating an insulation degradation pattern control chart in which regions are divided by the threshold value.

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