JP2018166164A - Molded transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain beauty of a molded transformer and furthermore to allow for easy diagnosis of deterioration in the molded transformer due irradiation with light or X-ray.SOLUTION: The molded transformer is provided which comprises an iron core and a molded coil molded with an insulating resin, and in which coating is applied to the surface of the molded coil, and a non-coated portion is provided on a part of the surface of the molded coil, and a seal is attached to the non-coated portion.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a molded transformer, and more particularly to a deterioration diagnosis of a molded transformer.

  There is a technique for performing deterioration diagnosis by irradiating light or X-rays in a molded transformer in which a coil of a transformer is molded with an insulating resin.

  Patent Document 1 describes a technique for irradiating a mold resin of a transformer with two types of light having different wavelengths using an optical fiber and determining the degree of deterioration from a difference in reflection absorbance or a ratio of reflection absorbance between the two wavelengths. (See Example 4).

Japanese Patent Laid-Open No. 10-74628

  The molded coil of the transformer is painted in order to maintain the appearance. Since this coating cannot transmit light and X-rays, the coating must be peeled off when performing the deterioration diagnosis of the coil. Moreover, there is a problem that the surface state may be changed by mechanical peeling with emery paper or the like, and the aesthetic appearance cannot be maintained even when the paint is peeled off. Patent Document 1 does not describe anything about coating.

  An object of the present invention is to make it possible to easily perform deterioration diagnosis by irradiation of light or X-rays while maintaining the beauty of a coil.

  In order to solve the above-described problems, in the present invention, a non-coating portion is created in advance when a mold coil is manufactured, and a seal is attached to the portion as an appearance improvement or a mark of a measurement site.

  An example of the molded transformer of the present invention is a molded transformer comprising an iron core and a molded coil molded with an insulating resin, and the surface of the molded coil is coated, A non-painted portion is provided on a part of the surface of the sheet, and a seal is attached to the non-painted portion.

  According to the present invention, it is possible to easily perform deterioration diagnosis by irradiation with light, X-rays or the like. In addition, since the deterioration diagnosis can be performed without removing the paint with emery paper or the like, the appearance of the coil can be maintained. Furthermore, since deterioration diagnosis at the same location is possible, there is an advantage that an aging tendency can be easily observed.

It is a perspective view of the mold transformer of Example 1. FIG. It is a perspective view of the mold transformer of Example 2. FIG. 6 is a front view of a three-phase coil of Example 3. FIG. It is a perspective view of the mold transformer of Example 4. It is a perspective view of the mold transformer of Example 5. FIG. It is a flowchart showing an example of the diagnostic method of the mold transformer of this invention in steps. It is a schematic diagram showing the distribution of the thermal stress applied to the interface between the energized part and the resin mold for electrical insulation and the resin mold for electrical insulation in the mold transformer. It is a block block diagram showing an example of the diagnostic system of the mold transformer of this invention. It is a figure showing an example of the fatigue life curve obtained from the fatigue life test of the resin mold for electrical insulation. It is a figure showing an example of the relationship between the stress concerning an interface part, and equivalent elapsed years created using the fatigue life curve. It is a figure which shows an example of the diagnostic method of the mold transformer of this invention. It is a figure which shows the external appearance of the mold transformer which has the resin mold for electrical insulation. It is a block block diagram which shows an example of the test | inspection means and display means of the diagnostic system of the mold transformer of this invention. It is an example of the display method of the diagnostic result of a mold transformer.

  Hereinafter, embodiments of the molded transformer of the present invention will be described with reference to the drawings. Note that, in the drawings for explaining the embodiments, the same constituent elements are given the same names and symbols as much as possible, and the repeated explanation thereof is omitted.

  In FIG. 1, the perspective view of the mold transformer of Example 1 of this invention is shown. FIG. 1 shows a molded transformer 100 having a three-phase tripod structure.

  In the figure, reference numeral 1 denotes an iron core, reference numeral 2 denotes a coil of each phase, reference numeral 3 denotes an upper metal fitting, and reference numeral 4 denotes a lower metal fitting. The coil 2 is obtained by molding a coil wound with a primary winding and a secondary winding with an insulating resin. The surface of the mold coil 2 is painted with a paint to keep the appearance beautiful.

  In the molded transformer of the present embodiment, a non-coating portion 7 is provided in a part of the coating portion 6 of the molded coil 2. The non-coating portion 7 is disposed in the upper corner portion (corner portion, R portion) of the coil where maximum stress is likely to occur. The size of the non-coating portion 7 is preferably about 10 mm in diameter, that is, 4 to 15 mm in diameter, since the diameter of the X-ray irradiation spot is about 4 mm at the maximum. The shape of the non-coating portion 7 is preferably substantially circular because it irradiates light or X-rays, and may be oval or square.

  A seal (covering member) 8 is attached to the non-coating portion 7 so as to cover the non-coating portion 7 in order to prevent contamination and maintain aesthetics. The seal 8 is preferably one that is easily peeled off during deterioration diagnosis.

  When diagnosing deterioration of the mold transformer 100, the deterioration of the mold resin of the coil is diagnosed by removing the seal 8 and irradiating the non-coating portion 7 with light or X-rays. By using light or X-rays, deterioration diagnosis can be performed in the operating state of the mold transformer. Details of the deterioration diagnosis method using light and X-rays are described in Patent Document 1, Example 6, and the like.

  According to the present embodiment, since the non-painted portion is provided on the surface of the mold coil and the seal is attached so as to cover the non-painted portion, light and X-rays are applied to the non-painted portion by removing the seal at the time of deterioration diagnosis. Irradiation makes it easy to diagnose deterioration. Further, by sticking the seal to the non-painted portion, it is possible to prevent the non-painted portion from being stained and to maintain the appearance of the appearance.

  In FIG. 2, the perspective view of the mold transformer of Example 2 of this invention is shown. In Example 2, as a sticker affixed to the non-coating part 7, what can understand the temperature of a coil like a thermo label is used. The thermo label 8a changes color according to temperature. As the affixing position, the upper corner portion where the heat of the resin is likely to accumulate and the thermal stress to the resin is likely to be generated is used.

  According to the present embodiment, since the seal that knows the temperature of the coil, such as a thermo label, is used, in addition to the effects of the first embodiment, the temperature during operation of the molded transformer can be observed.

  In FIG. 3, the front view of the mold transformer of Example 3 of this invention is shown. The rear view of the mold transformer is also the same as FIG. In Example 3, in the coil 2 of each phase, the non-coating part 7 is provided in the upper four corner parts (corner part, R part). Then, as in the first embodiment, a seal 8 is attached to the non-painted portion 7.

  According to the present embodiment, since the non-painted portions are provided at the upper four corner portions in the coils of each phase, in addition to the effects of the first embodiment, when the transformer is housed in the cubicle, No matter how it is stored, deterioration diagnosis using light or X-rays can be performed.

  In FIG. 4, the perspective view of the mold transformer of Example 4 of this invention is shown. In the fourth embodiment, a seal 8 b having a color different from the color of the paint on the painted portion 6 is used as a seal to be attached to the non-painted portion 7. By using the seal 8b having a color different from the color of the paint, it is easy to specify the position where light or X-rays are irradiated.

  According to the present embodiment, by using a seal having a color different from the color of the paint, in addition to the effects of the first embodiment, it is possible to easily specify the position where light or X-rays are irradiated during deterioration diagnosis. .

  In FIG. 5, the perspective view of the mold transformer of Example 5 of this invention is shown. In Example 5, a transparent seal 8c is used as a seal to be attached to the non-coating portion 7. By using a transparent seal, deterioration diagnosis using light or X-rays can be performed without removing the seal.

  According to the present embodiment, by using a transparent seal as a seal to be affixed to the non-painted portion, in addition to the effects of the first embodiment, the deterioration of irradiating light or X-rays without removing the seal at the time of deterioration diagnosis Diagnosis can be made.

  An example of a diagnostic method for the molded transformer of the present invention will be described in detail as Example 6.

(Form 1)
FIG. 6 is a flowchart showing in a stepwise manner an example of the mold transformer diagnosis method of the present embodiment.

  As shown in FIG. 6, the mold transformer diagnosis method of the present embodiment includes a first step (measurement of stress applied to the surface layer portion of the resin mold) and a second step (stress applied to the surface layer portion of the resin mold). Conversion to stress at the interface with the energized part), and a third step (conversion of stress at the interface with the energized part of the resin mold into a corresponding elapsed time).

  As shown in FIG. 6, in order to obtain the diagnosis result 13, analysis, test, and measurement are performed on each of the electrical device 11 and the test piece 12 of the resin mold material included in the electrical device. In addition, the test piece 12 of the resin mold material with which an electric equipment is equipped may be the test piece cut out directly from the electric equipment 11 which actually operate | moves, and it has the completely same chemical composition and composite material composition as this, and resin manufactured separately It may be a test piece of material. In addition, in a present Example, the electric equipment 11 is the mold transformer demonstrated in Examples 1-5.

  The flow from 11A to 11C shown in FIG. 6 relates to numerical analysis by the finite element method for the electric device 11, and is performed before actually diagnosing the electric device, and the result is stored in the database. Specifically, in the electrical device modeling 11A, finite element modeling is performed based on the component structure of the electrical device. For each element of the model created in the electrical device modeling 11A, the material properties of the material that actually configures each part of the electrical device 11, such as a current-carrying part or a resin mold, are input. Here, the material physical properties are mechanical physical properties such as Young's modulus and Poisson's ratio, and thermal physical properties such as linear expansion coefficient and thermal conductivity.

  In the thermal stress analysis 11B, the thermal stress analysis of the electrical device 11 is performed using the model created in the electrical device modeling 11A. At this time, in order to reproduce the state in which the electrical device 11 is exposed to the energization load, the current value is obtained from Ohm's law using the electrical resistance and voltage at the energization site in the model, and then the heat is generated from Joule's law. Find the amount.

  Thermal stress analysis is performed in consideration of heat generation at the energized portion. For example, when the energization site is a coil, the electrical resistance and voltage can be calculated from the total length of the windings constituting the coil and the cross-sectional area of the windings. When the thermal stress analysis 11B is performed, the distribution of stress applied to the resin mold included in the electrical device 11 can be found. The obtained stress value includes the residual stress resulting from the shape of the resin mold in addition to the thermal stress generated when the heat generated at the energized portion is transferred to the resin mold.

  Here, as shown in FIG. 7, the stress distribution is a value of stress at each position from the interface portion 23 between the energized portion 21 and the resin mold 22 for electrical insulation to the surface layer portion 24 of the resin mold. means.

  FIG. 7 is a schematic diagram of the stress distribution, and the stress S1 applied to the interface portion 23 and the stress S2 applied to the surface layer portion 24 are extracted from the distribution. In FIG. 7, the stress S <b> 2 applied to the surface layer portion 24 is shown to be smaller than the stress S <b> 1 applied to the interface portion 23, but the stress S <b> 2 applied to the surface layer portion 24 may be greater than the stress S <b> 1 applied to the interface portion 23. It doesn't matter if they are equal.

  In the resin mold stress ratio database 11 </ b> C, the ratio between the stress S <b> 1 and the stress S <b> 2 obtained from the thermal stress analysis, that is, the value of S <b> 1 / S <b> 2 is created as a database. The thermal stress analysis is performed on the electrical device 11 having various dimensions, output, and energized state. Therefore, the stress ratio obtained from the thermal stress analysis is functionalized according to the size, output, usage environment, energized state, etc. of the electrical equipment 11 when creating a database.

  Here, the usage environment includes information such as the temperature, humidity, and air pollution level of the place where the electric device 11 is operated, and the energized state refers to the average energization time per year and the current peak value in one day. It includes information such as the hold time and what percentage of the maximum output of the electrical equipment is used.

  In addition to the flow from 11A to 11C shown in FIG. 6, the flow from 12A to 12B is also performed before actually diagnosing the electric device, and the result is stored in the database. The flow from 12A to 12B relates to a fatigue life test for the test piece 12 of the resin mold material included in the electric device.

  Specifically, in the fatigue life test 12A, a fatigue life test is performed on the test piece 12 of the resin mold material included in the electric device. The fatigue life test is performed by processing a test piece 12 of a resin mold material included in an electrical device into, for example, a strip shape or a dumbbell shape, fixing one end of the processed test piece, and applying a tensile load to the other end. Done.

  The size of the test piece may be in accordance with, for example, JIS K 7139 standard. The tensile load is repeatedly applied, and the repetition frequency and the maximum value of the load are arbitrary. When a repeated tensile load is applied, the test piece breaks at a certain number of repetitions.

  A fatigue life curve can be obtained by performing such a test several times while changing the maximum value of the tensile load, and plotting the number of repetitions leading to fracture on the horizontal axis and the maximum value of the tensile load on the vertical axis. .

  The fatigue life curve obtained as a result of the fatigue life test has a stress value when a logarithmic scale is used for the number of repetitions leading to the rupture of the horizontal axis in accordance with empirical formulas such as exponential Basquin rule and Coffin-Manson rule. It becomes a decreasing curve.

  When the fatigue life curve is approximated by the above empirical rule, the tensile strength is obtained from the intercept, and a coefficient representing the degree of attenuation of the stress value is obtained from the exponent part, that is, two material fatigue constants are obtained. In the material fatigue constant database 12B, this material fatigue constant is databased as a numerical value unique to the test piece 12 of the resin mold material provided in the electric equipment.

  The fatigue life test can be performed on the test piece 12 made of a resin mold material provided in an electric device having various material compositions. Therefore, the material fatigue constant obtained from the fatigue life test is functionalized according to the material composition of the test piece 12 of the resin mold material included in the electric device when the database is created.

  Here, the material composition means the types of resin main agent, curing agent, colorant, reinforcing agent, and the like and the mixing ratio thereof that constitute the test piece 12 of the resin mold material provided in the electric device.

  The flow from 11A to 11C and the flow from 12A to 12B shown in FIG. 6 make preparations for diagnosing the electrical device 11. From here, three diagnostic steps will be described.

  In <1st process S101> in FIG. 6, the stress S2 concerning the surface layer part 24 of the resin mold for electrical insulation with which the electric equipment 11 is provided is measured. The stress is measured by a nondestructive inspection method. At this time, the electrical device 11 may be in an energized load state or in a power failure state.

  The obtained stress value includes the residual stress resulting from the shape of the resin mold in addition to the thermal stress generated when the heat generated at the energized portion is transferred to the resin mold. The nondestructive inspection is performed using a stress measuring device using synchrotron radiation such as X-rays. Irradiation of radiation light such as X-rays is applied to the non-coating portion 7 of the mold transformer of Examples 1 to 5. In this case, the stress is measured from the X-ray diffraction of the inorganic filler compounded with the resin mold. The stress acting on the powdered composite inorganic filler may be regarded as the stress applied to the resin mold itself.

  This is because the measured stress value reflects the adhesion state between the inorganic filler and the resin base material at the micro level. Specifically, at the time of resin molding, the inorganic filler and the resin base material are firmly adhered at a micro level, and an equivalent and non-zero stress acts on both the inorganic filler and the resin base material. When aged or a thermal load is applied, the adhesion between the inorganic filler and the resin base material becomes weak, and the stress is eventually released.

  Therefore, by measuring the stress acting on the inorganic filler, it is possible to measure the stress S2 applied to the surface layer portion 24 of the resin mold for electrical insulation provided in the electrical device 11 that changes due to aging or thermal load.

  The microstructure of the powder of inorganic filler compounded in the resin mold for electrical insulation may be either crystalline with regular atomic arrangement or amorphous with irregular atomic arrangement, but stress measurement by X-ray In the case of conducting, it is necessary to be crystalline having a clear diffraction pattern.

  Examples of the crystalline inorganic filler include crystalline silica, aluminum oxide, aluminum hydroxide, calcium carbonate, iron oxide, titanium oxide, zirconium oxide, cesium oxide and the like. Moreover, the compounding quantity of an inorganic filler is arbitrary.

  In other words, the first process described above is a resin internal state inspection process, a surface layer stress inspection process, or an interface stress inspection process.

  In the <second step S102>, the stress S2 applied to the surface layer portion 24 of the resin mold for electrical insulation provided in the electrical device 11 obtained in the <first step S101> and the stress ratio accumulated in the stress ratio database 11C The product of (S1 / S2) is calculated and converted to the stress S1 applied to the interface 23 with the energized part.

  As described above, since the stress ratio is functioned according to the size, output, and energization state of the electrical device 1, a stress ratio that matches the status of the electrical device used for diagnosis is input.

  In the <third step S103>, the stress S1 applied to the interface part 23 between the energized part and the resin mold for electrical insulation obtained in the <second step S102> is applied to the fatigue life curve, and the number of repeated stress loads is calculated. Convert.

  The fatigue life curve is created by substituting the two material fatigue constants in the database obtained in 12B into an empirical expression such as an exponential-type Basquin rule or Coffin-Manson rule. By substituting the stress S1 of the interface 23 for the fatigue life curve, the number of repetitions corresponding to the stress can be obtained.

  As described above, since it is functionalized by the material composition of the test piece 12 of the resin mold material provided in the electric equipment, a material fatigue constant corresponding to the situation of the electric equipment used for diagnosis is input.

  In other words, the second process described above is a resin mold stress specifying process, a resin mold internal stress specifying process, a current-carrying part stress specifying process, or an interface stress specifying process.

  In <third step S <b> 103>, the number of repetitions obtained from the fatigue life curve is converted into the number of elapsed years of the electrical device 11. For example, if you continue to use an electrical device at maximum output for a long period of time and the thermal load on the resin mold is repeated, the electrical device has accumulated more years than actually passed from the date of manufacture of the electrical device. It becomes equal to the state of.

  The equivalent age is the number of years that have elapsed in the use of electrical equipment, which is obtained in consideration of such usage conditions. In the above, an example in which the equivalent elapsed years are longer than the actual elapsed years has been shown. However, the equivalent elapsed years may be shortened, for example, when the electronic device is stored without being used at all.

  Conversion of the number of repetitions obtained from the fatigue life curve to the equivalent elapsed years is performed by a conversion coefficient. For example, when an electric device is operated continuously regardless of day and night, the thermal stress increases and decreases once due to the temperature difference between day and night.

  In this case, the conversion coefficient is 1 day / time. By multiplying the number of repetitions obtained from the fatigue life curve by this conversion coefficient and making it a year unit, an equivalent elapsed time can be obtained.

  In the third step, based on the material fatigue constant obtained from the material fatigue constant database, the relationship between the stress applied to the interface and the corresponding elapsed time is obtained, and this relationship is obtained in the second step. Alternatively, the stress applied to the surface layer portion may be applied to obtain the equivalent elapsed years.

In addition, the remaining life can be obtained by subtracting the number of elapsed years of the electrical equipment from the design life of the electrical equipment.
The remaining life means the remaining number of years that the electrical equipment can be safely used while ensuring electrical insulation. When the remaining life shows a negative value, the electric device has already reached the state exceeding the design life.

  In other words, the above-described third step is equivalent age specification processing, resin mold equivalent age specification processing, or mold transformer equivalent life specification processing.

  FIG. 8 is a block diagram showing a diagnostic system for a molded transformer according to this embodiment. The electrical equipment diagnosis system includes a surface layer stress measurement device 30 and a diagnosis device 40.

  The surface layer stress measuring device 30 is a device that measures the stress S2 applied to the surface layer portion 24 of the resin mold for electrical insulation provided in the electric device 11, and uses, for example, an X-ray stress measuring device that measures stress from X-ray diffraction. be able to.

  The diagnostic device 40 includes an interface stress calculator 42, a resin mold stress ratio database 43, an equivalent elapsed years calculator 44, a material fatigue constant database 45, and a display 46. The resin mold stress ratio database 43 performs finite element modeling based on the component structure of the electrical equipment, performs thermal stress analysis of the electrical equipment, and obtains the stress ratio S1 / S2 between the surface layer stress and the interface stress, It is a database.

  Further, the material fatigue constant database 45 is a database in which the fatigue life curve is obtained by conducting a fatigue life test on the test piece of the resin mold material provided in the electric equipment, and the material fatigue constant obtained from the fatigue life curve is made into a database. .

  The interface stress calculation unit 42 calculates the product of the surface layer stress S2 measured by the surface layer stress measurement device 30 and the stress ratio accumulated in the resin mold stress ratio database 43, and calculates the stress S1 applied to the interface. To do.

  The equivalent elapsed year calculation unit 44 applies the interface stress obtained by the interface stress calculation unit 42 to a fatigue life curve created based on the material fatigue constants in the material fatigue constant database 45 to obtain the number of stress load repetitions.

  Then, the number of stress load repetitions is converted into an equivalent number of years of electrical equipment. The display part 46 displays the equivalent elapsed years of the obtained electrical equipment. The display unit 46 may be provided in the diagnostic device 40, or may be a tablet terminal or the like that is separate from the diagnostic device, and a display signal may be transmitted from the diagnostic device thereto. In FIG. 8, the surface layer stress measuring device 30 and the diagnostic device 40 are described as separate devices, but the two devices may be integrated into one device.

  The diagnostic method and diagnostic system for a mold transformer described above is based on the thermal stress applied to the resin mold at the interface 23 between the energized portion inside the mold transformer and the resin mold, which regulates the failure of the mold transformer. It is possible to provide a highly accurate diagnostic technique for obtaining the equivalent age and remaining life of a transformer.

  Next, this embodiment will be described more specifically.

  The transformer used for diagnosis includes a coil wound with a copper wire as a current-carrying portion, and a resin mold around the coil for electrical insulation. The resin mold is made of a composite material of epoxy resin and contains crystalline silica as a main filler.

[1] Derivation of stress ratio by thermal stress analysis The mold transformer was modeled by a finite element, and thermal stress analysis was performed by the finite element method. Using the test piece, the mechanical and thermal properties of the constituent materials were measured in advance and assigned to each element. In the thermal stress analysis, the heat generation amount at the energized portion was obtained from the total length of the windings constituting the coil and the cross-sectional area of the windings, and the heat transfer to the resin mold was taken into consideration.

  From the resulting stress distribution on the resin mold, the ratio (S1 / S2) of the stress on the resin mold at the interface with the coil and the stress on the surface layer of the resin mold was determined.

  Table 1 shows the analysis results of the stress ratio for three transformers having different dimensions, outputs, and energized states. No. 1, No. 2, No. 3 All transformers have been used for 10 years since the start of energization. In the dimensions, the height of the coil portion is shown as a representative value.

  The energization load factor is the ratio of the load factor in actual use to the maximum capacity of the transformer. The larger this value, the greater the heat generation, and the greater the generation of thermal stress. No. in Table 1 1 and No. From the comparison of 2, it can be seen that the stress ratio increases as the energization load factor increases.

  No. 2 and No. From the comparison of 3, it can be seen that the stress ratio increases when the dimensions are large. Table 1 is an example of a resin mold stress ratio database 11C.

[2] Derivation of material fatigue constant by fatigue life test Transformer No. shown in Table 1 1, No. 2, No. A fatigue life test was performed on a composite resin test piece having the same material composition as that of the resin mold for electrical insulation 3. The test piece was dumbbell shaped according to the JIS standard for plastic test pieces as described above.

  In the fatigue life test, ten types of stress values were set, and repeated tensile tests were performed at each stress value, thereby obtaining the number of repetitions until the resin test piece was broken.

  FIG. 9 shows a fatigue life curve obtained from the fatigue life test. The fatigue life curve is plotted with an exponential Basquin rule. No. 1, No. The curve 2 has an intercept of 110 MPa and an exponential coefficient of -0.04. The three curves have an intercept of 100 MPa and an exponential coefficient of -0.08.

  Transformer No. The resin mold material used for 3 is transformer no. 1, No. Compared with the resin mold material used in 2, the material fatigue constant, that is, the tensile strength obtained from the intercept and the coefficient representing the degree of attenuation of the stress value obtained from the exponent part are both small.

  From this, transformer no. The resin mold material used for 3 is transformer no. 1, No. It can be seen that the amount of decrease in the stress value increases with an increase in the number of repetitions in addition to the original tensile strength being smaller than the resin mold material used in 2. Table 2 shows an example of the obtained material fatigue constant database 12B.

[3] Diagnosis of Mold Transformer Using the stress ratio S1 / S2 obtained in [1] and the material fatigue constant obtained in [2], the mold transformer was actually diagnosed.

  <First Step> First, using a surface layer stress measuring device, transformer No. 1, No. 2, No. 3 The stress acting on the surface layer portion of each resin mold for electrical insulation was measured. In these resin molds, crystalline silica is blended as a filler. Therefore, the stress acting on the surface layer portion of the resin mold was measured by the X-ray diffraction stress measurement method.

  <Second Step> Next, the stress applied to the surface layer portion of the resin mold is calculated by using the stress ratio S1 / S2 stored in the stress ratio database obtained in [1] at the interface stress calculation section. Converted into stress acting on the resin mold at the interface with the coil to be molded.

  <Third Step> Finally, in the equivalent elapsed years calculation unit, using the material fatigue constant stored in the material fatigue constant database obtained in [2], the resin mold at the interface with the coil molded by the resin mold is used. The acting stress was converted into the number of repetitions in the fatigue life curve, and then converted into an equivalent number of years using a conversion coefficient.

  The transformer of this example is operated continuously regardless of day and night, and because the increase and decrease in thermal stress occurs once a day due to the temperature difference between day and night, the conversion coefficient was set to 1 day / time. In order to obtain the equivalent elapsed years, the relationship between the stress applied to the interface portion created in advance and the equivalent elapsed years may be used, and an example is shown in FIG. Table 3 shows the transformer no. 1, No. 2, No. The diagnostic results for each of the three were summarized.

  No. 1 and No. From the comparison of 2, it can be seen that even with the same transformer, the greater the energization load factor, the greater the thermal stress applied to the interface portion of the resin mold, and thus the greater the number of elapsed years. No. 2 and No. From the comparison of 3, it can be seen that even when the current load factor is the same, if the transformer size is large, the residual stress and thermal stress applied to the interface part of the resin mold increase, and the corresponding elapsed time increases. .

  As described above, No. 1, No. 2, No. 3 All transformers have been used for 10 years since the start of energization. No. One transformer is diagnosed as having an actual age equivalent to the equivalent age. On the other hand, No. 2 and No. Transformer 3 is diagnosed with a substantial age that exceeds the actual age.

  No. 1, No. 2, No. 3 All transformers are designed with a lifetime of 30 years. By subtracting the equivalent number of years from the life of 30 years, the remaining life of the transformer is No. 1 No. 19.9, No. 1 2 for 15.2 years, No. 2 3 can be calculated as 7.4 years, and from the outside of the transformer, the signs of internal interface peeling and resin mold cracking that cause failure can be digitized and diagnosed appropriately.

  As described above, the peeling of the interface between the energized portion inside the electric device and the resin mold and the cracking of the resin mold are due to repeated thermal stresses that are naturally applied during operation of the electric device. In the above embodiment, it is possible to directly know precursors such as peeling of the interface between the energized portion and the resin mold and cracking of the resin mold, which cannot be visually observed from the outside of the electric device. It was shown that accuracy can be achieved.

(Form 2)
FIG. 11 is a diagram illustrating an example of an inspection method by nondestructive inspection of a resin mold according to the present embodiment. The mold transformer 100 has a resin mold 110. A state in which the resin mold 110 is imaged by the inspection means 120 is shown. A state in which light or X-rays are irradiated from the inspection unit 120 and reflected from the resin mold 110 is shown. The life information of the mold transformer 100 to be described later is displayed on the display means 150, and the display result is observed by the inspector 200.

  FIG. 12 shows an example of a diagnosis region of the mold transformer 100 having the resin mold 110 to be diagnosed shown in FIG. Diagnosis areas described later may be performed with areas or resolutions, but are described here as areas A111, B112, and C113.

  An example of the configuration of the inspection unit 120 and the display unit 150 illustrated in FIG. 11 will be described with reference to FIG. The inspection means 120 is used to observe or image the resin mold 110. Although the inspection unit 120 will be described as an inspection, it may be imaging or photographing, and may be any unit that can observe the surface state of the resin mold 110.

  The inspection unit 120 will be described later using a detection unit 121 that images the surface of the resin mold 110, a storage unit 122 that stores the captured image of the resin mold, and an image of the resin mold 110 stored in the storage unit 122. It has a control unit 123 that calculates the number of elapsed years and a communication unit 124.

  Moreover, you may have the display part 125 in the test | inspection means 120 as needed. The display unit 125 displays the image and data acquired by the detection unit 121 and displays information received from the communication unit 124.

  The detection unit 121 images the surface of the resin mold 110 formed so as to cover the coil of the mold transformer 100. The storage unit 122 stores temperature distribution information on the surface of the resin mold 110. Further, the method described in the first embodiment may be used without using the temperature distribution information.

  In this embodiment, the imaging method uses thermography for observing the surface temperature distribution of the resin mold 110. In the present embodiment, it is only necessary to observe the surface temperature distribution, and not only thermography but also an imaging method capable of acquiring the infrared wavelength as a numerical value from the inspection object.

  Further, it is not essential to measure the surface temperature of the entire resin mold 110 such as thermography in order to specify the surface stress using thermal stress analysis. The surface layer stress can be specified only by measuring a part of the temperature. In this case, for example, it can be carried out if the temperature of the portion irradiated with the laser light can be measured. The method is not limited to laser light, and a method of measuring the temperature of the resin mold 110 by means such as a thermometer may be employed. More accurate thermal stress analysis can be performed by measuring a wider area than pinpoint temperature measurement.

  Here, the detection unit 121 can acquire the temperature distribution on the surface of the resin mold 110 by performing it while the mold transformer 100 is in operation (also referred to as an operating state). This is because in order to calculate the thermal stress from the surface temperature distribution of the resin mold 110, it is necessary to acquire the temperature distribution during operation.

  The method of thermal stress analysis is performed using the temperature distribution on the surface of the resin mold 110 in the operating state. The resin mold stress ratio database 11C and the thermal stress analysis 11B shown in FIG.

  Specifically, the control unit 123 acquires or converts the surface temperature distribution of the image captured by the detection unit 121, and then processes in the order of the first step S101, the second step S102, and the third step S103. . The life or deterioration state of the mold 110 is specified by such processing steps.

  The first to third steps S101 to S103 may be performed by the control unit 153 of the inspection unit 120 or the control unit 153 of the display unit 150, or may be performed by another computer or the like.

  The principle of specifying the remaining life or the deterioration state using the surface layer stress and the interface stress will be briefly described. The resin mold 110 at the time of shipment of the mold transformer 100 has a shrinkage stress on the coil. The shrinkage stress is generated by shrinkage when the resin mold 110 before solidification covering the coil is solidified. Insulating property can be maintained by covering the coil with the resin mold 110 which is an insulating member.

  In the resin mold 110, since the resin deteriorates with the use time, the shrinkage stress decreases with time from the production of the mold transformer 100.

  In addition, the resin mold 110 is heated by the operation of the mold transformer 100, and then the cooling or heat dissipation is performed by decreasing the load factor. At this time, the resin mold 110 undergoes thermal expansion and contraction, and the load stress (interfacial stress) between the coil and the resin mold 110 changes.

  By repeating this, the force for holding the coil of the resin mold 110 becomes weak, and the load stress of the resin mold 110 gradually decreases from the time of manufacture.

  Further, when the load stress is lowered, there may be a gap between the coil and the resin mold 110 and partial discharge may occur. When the value of the partial discharge exceeds a predetermined value, the mold transformer 100 needs to be replaced. Further, it is considered that the partial discharge can also be caused by scattering of silica inside the resin mold 110.

  From the above, by specifying the load stress of the resin mold 110 at the time of shipment and the operating state of the transformer, that is, the state of thermal contraction and thermal expansion of the resin mold, the value of the gap between the resin mold and the coil is converted. Can be identified.

  The control unit 123 calculates the surface stress of the resin mold 110 by performing thermal analysis using the temperature distribution information on the surface of the resin mold 110 stored in the storage unit 122. The voids can be specified using the processing method for specifying the interface stress using the stress ratio described in the first embodiment. Also, it is better to specify the gap at the interface between the coil of the same model and the resin mold 110 and the stress at the interface, and if possible, specify the amount of the gap more accurately by matching with the data when disassembled in the past. can do.

  Here, the control unit 123 may also specify the temperature distribution information on the surface of the resin mold 110. For example, when the detection unit 121 has a means for detecting the wavelength of infrared rays, calculation and conversion from the wavelength and intensity to temperature distribution information can be performed.

  An example of a method for calculating the interface stress using the temperature distribution information will be described. First, the interface stress at the time of shipment is specified for the transformer to be measured. Interfacial stress measurement is not limited to those using thermal stress analysis, but is compared with actual data of interfacial stress measured by disassembling the resin mold of a transformer of the same model or model number, and the resin to be measured The mold may be compared and specified.

  Further, similarly to the first embodiment, the equivalent elapsed years (also referred to as equivalent use years or substantial transformer age) of the imaged mold transformer 100 may be specified using the surface layer stress and the interface stress.

  Here, the equivalent elapsed years is a concept of a virtual elapsed years considering a use state specified from an actual use environment, unlike the time when the mold transformer 100 is actually used.

In other words, the service life of the mold transformer 100 is specified assuming a predetermined operating state and a load factor to be used. However, if the use is continued in an environment where the load factor is high with respect to the predetermined operating state, etc., If it is assumed that a large amount of time has passed and the use is continued in an environment where the load factor is low with respect to a predetermined operation state or the like, the number of years elapsed is considered to be small.
Note that when the load factor is low with respect to a predetermined operation state or the like, the influence of the deterioration of the resin mold 110 due to thermal stress is small, so that the considerable elapsed time may coincide with the actual use time.

  As an example to explain the concept of equivalent elapsed years, if the usage load factor is continuously used at 120% with respect to the load factor used when calculating the life of the transformer, it is determined that the equivalent elapsed year has also passed as 120%. That's what it means. In other words, a transformer that has been used for 10 years with a load factor of 120% is equivalent to 12 years.

  Here, the identified equivalent elapsed years are displayed on the display means 150 shown in FIG. You may display on the test | inspection means 120 as needed.

  As shown in FIG. 13, the display unit 150 is operated by the communication unit 154 that communicates with the inspection unit 120 and other devices, the control unit 153 that calculates and calculates the communication information, and the control unit 153. A storage unit 152 that stores the received information, and a display unit 155 that displays the information stored in the storage unit 152 and the communicated information. You may have input means, such as a touch panel, a keyboard, and a mouse | mouth.

Next, a display method of the equivalent elapsed years will be described with reference to FIG.
Transformer surface temperature distribution information 500 is displayed in the upper left area of the display unit 155 of the display means 150. Further, a measurement region 501 corresponding to the transformer surface temperature distribution information 500, a surface temperature 502, and a measurement value 503 are displayed on the upper right side of the display unit 155.

  Further, in the lower part of the display unit 155, the model information 511 of the measured mold transformer 100, the size information 512 of the transformer, the stress gradient value information 513, the actual age information 514 (the actual age, the actual age) Equivalent age information 515 (also called real transformer age) is displayed. It is not necessary to display all of these pieces of information, and at least the equivalent elapsed year information 515 can be displayed.

  Further, the transformer surface temperature distribution information 500 divides the area into large areas, and in this example, three areas A, B, and C are displayed. Each region can be colored or hatched to visualize the surface temperature.

  On the upper right side, the average temperature of the areas A, B, and C of the measurement area 501 and the temperature at the position of the cursor 505 are displayed as the surface temperature 502. The surface portion stress 503 calculated from the surface temperature information is displayed.

  The cursor 505 moves by operating the touch panel or operating the cursor 505, and appropriately displays the temperature at the position of the cursor 505. As a result, the transformer surface temperature distribution information 500 can know not only the rough surface temperature in the region using the color map but also the detailed surface temperature at a specific position.

  In the lower part, the equivalent elapsed years 515 specified using the information on the surface stress 503 and the interface stress 504 are displayed. In addition, the actual number of years 514 (the actual usage time of the transformer) is displayed. This makes it possible to compare the actual usage time with the equivalent elapsed years of the transformer. In this case, it means that the diagnosed mold transformer 100 has been used for four years more than the actual usage time.

  Further, the stress gradient rate 513 specified based on the amount of change in the surface portion stress 503 may be displayed. The stress gradient rate indicates the amount of change between shipment and measurement. The stress gradient rate 513 may be specified using the interface stress 504. In any case, by displaying the stress gradient value 513, it is possible to indicate the degree of progress of the assumed usage time with respect to the actual usage time of the mold transformer 100.

  In this example, in the case of a molded transformer with a service life of 30 years, the actual use time was 25 years, but the elapsed time (actual transformer age) is 29 years. Because there is, it turns out that the exchange time is near. That is, it can be seen that the mold transformer 100 to be measured was used in an environment where the estimated usage time is added to the actual usage time, and can be notified to the user that replacement is necessary. Therefore, it is possible to know the replacement time of the mold transformer using the corresponding elapsed years.

  In addition to the surface temperature 502, the surface portion stress 503 may display the surface portion stress calculated by observing the surface portion of the resin mold 110 using the X-ray of the first form.

  Furthermore, it is possible to specify the equivalent elapsed years with higher accuracy by inspecting a portion having a high temperature in the measurement region using the X-ray from the transformer temperature distribution information 500 and the surface temperature 502.

  Furthermore, since the mold transformer 100 is often operated for a long time in a predetermined load state at a predetermined time zone, the temperature distribution on the surface of the resin mold 110 for one day is observed over time such as time-lapse observation. The thermal stress of the resin mold up to can be estimated more accurately.

  Moreover, if the temperature distribution of the surface of the resin mold 110 according to the load factor (load state) of the mold transformer 100 is acquired, the relationship between the load factor and the surface temperature distribution can be specified, and the surface stress with higher accuracy can be specified. As a result, a highly accurate life diagnosis can be performed.

  It is also possible to compare with the outside air temperature together with the imaging of the detection unit 121. In this case, the relationship between the outside air temperature and the surface temperature distribution of the resin mold 110 can be obtained, which can contribute to highly accurate life diagnosis.

DESCRIPTION OF SYMBOLS 1 ... Iron core, 2 ... Coil, 3 ... Upper metal fitting, 4 ... Lower metal fitting, 6 ... Painted part, 7 ... Non-coating part, 8 ... Seal (covering member), 8a ... Thermo label, 8b ... Color different from a coating part Seal, 8c ... transparent seal,
DESCRIPTION OF SYMBOLS 11 ... Electrical equipment, 11A ... Modeling of electrical equipment, 11B ... Thermal stress analysis, 11C ... Resin mold stress ratio database, 12 ... Test piece, 12A ... Fatigue life test, 12B ... Material fatigue constant database, 13 ... Diagnosis result,
21 ... Current-carrying site, 22 ... Resin mold for electrical insulation, 23 ... Interface part, 24 ... Surface layer part,
DESCRIPTION OF SYMBOLS 30 ... Surface part part stress measuring device, 40 ... Diagnostic apparatus, 42 ... Interface part stress calculation part, 43 ... Resin mold stress ratio database, 44 ... Equivalent elapsed years calculation part, 45 ... Material fatigue constant database, 46 ... Display part,
S101 ... 1st process, S102 ... 2nd process, S103 ... 3rd process,
S1 ... stress at the interface, S2 ... stress at the surface layer,
DESCRIPTION OF SYMBOLS 100 ... Mold transformer, 110 ... Resin mold, 111 ... Area | region A, 112 ... Area | region B, 113 ... Area | region C, 120 ... Inspection means, 121 ... Detection part, 150 ... Display means, 155 ... Display part, 200 ... Inspector .

Claims (14)

A mold transformer comprising an iron core and a mold coil molded with an insulating resin, the surface of the mold coil being coated,
A non-coating part is provided on a part of the surface of the mold coil,
A molded transformer, wherein a seal is affixed to the non-painted portion. The molded transformer according to claim 1,
The molded transformer, wherein the seal can be peeled off. The molded transformer according to claim 1,
The molded transformer, wherein the non-coating portion is provided at an upper corner portion of the molded coil. The molded transformer according to claim 1,
The non-painted portion is a substantially circular shape having a diameter of 4 to 15 mm. The molded transformer according to claim 1,
The molded transformer, wherein the seal is a seal whose color changes according to temperature. The molded transformer according to claim 1,
The said non-coating part is provided in the upper four corner parts in the mold coil of each phase, The mold transformer characterized by the above-mentioned. The molded transformer according to claim 1,
The mold transformer is characterized in that the seal is a seal having a color different from the color of the paint in the painted portion. The molded transformer according to claim 1,
The molded transformer, wherein the seal is a transparent seal. In the mold transformer according to any one of claims 1 to 8,
The non-painted part is a non-painted part for irradiation with light or X-rays. A transformer having an iron core and a coil wound around the iron core,
The outer peripheral side of the coil is covered with a resin member,
The said resin member has a coating area | region and a non-coating area | region on the surface, The transformer characterized by the above-mentioned. The transformer according to claim 10,
The transformer is characterized in that the non-coating region is disposed at an upper corner portion of the coil. The transformer according to claim 10,
The said non-coating area | region is provided with the coating | coated member which covers this non-coating area | region. The transformer according to claim 12,
The transformer is characterized in that the covering member can be peeled off. The transformer according to any one of claims 10 to 13,
The non-painting region is a non-painting region for light or X-ray irradiation.

Images