JP2017183477A - Flow charge evaluation diagnosis method for electrical equipment, and flow charge evaluation diagnosis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diagnosis method capable of evaluating flow charge of electrical equipment for both an insulative liquid of a transformer being used at present and a solid insulator.SOLUTION: The present invention relates to a flow charge evaluation diagnosis method for electrical equipment in which a solid insulator and an electrification body are immersed in an insulative liquid. The flow charge evaluation diagnosis method for the electrical equipment is characterized in that the insulative liquid sampled from the electrical equipment and solid insulator particles contained in the insulative liquid are charged and flow charge is evaluated.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method and a diagnostic apparatus for diagnosing easiness of flow charge generation in an electrical apparatus including an insulating liquid and a solid insulator.

Flow electrification in a transformer is a phenomenon in which electric charge is separated at the interface of a solid insulator due to the flow of insulating oil inside the transformer, and charge is accumulated in the insulator inside the winding and around the oil passage. is there. In a transformer with insulating oil, an insulating oil flow path is provided to improve the flow of the insulating oil. This is called an oil passage. In the portion where the charge is accumulated, the direct current potential may increase and electrostatic discharge may occur, and there is a risk of dielectric breakdown depending on conditions.
As described above, in an electric device using insulating oil as an insulating liquid, a flow electrification phenomenon may occur between the insulating liquid and the solid insulator, which may threaten the insulating property of the electric device.
For this reason, conventionally, as a method for evaluating the degree of fluid charging with respect to actual electrical equipment, the mini electrostatic tester method described in Non-Patent Document 1 and the accumulated charge density method described in Non-Patent Document 2 have been studied. .

The mini electrostatic tester method is evaluated by measuring the current through a metal mesh with a paper filter, charged with insulating oil collected from a local transformer and a paper filter (simulated structure of the solid insulation of the transformer). It is a method to do.
However, when the mini electrostatic tester method is implemented, the paper filter does not sufficiently reproduce the insulation in the transformer in operation, so the mini electrostatic tester method has an effect on the flow charge of the insulating liquid alone. Can be evaluated, but solid insulators cannot be evaluated.

  On the other hand, in the accumulated charge density method, it is necessary to collect an insulating liquid and a solid insulator from the inside of an electric device. However, since it is difficult to directly collect the solid insulation from the electrical equipment in operation, it was actually collected from the electrical equipment in operation to a new solid insulation without collecting the solid insulation from the actual electrical equipment. It is necessary to impregnate with insulating oil and apply the accumulated charge density method. In addition, since the accumulated charge density method requires a large construction period and cost, it is not easy to apply it to actual equipment.

Electric Cooperative Research Vol. 54, No. 5 (Part 1) “Maintenance Management of Oil-filled Transformers” by Electric Power Transformer Maintenance Management Special Committee, Electric Cooperative Research Society February 1999, P133, 7 -2-1 Electric Cooperative Research Vol. 65 No. 1 “Power Transformer Reform Guidelines” by Electric Power Transformer Maintenance Management Special Committee, Electric Cooperative Research Society, February 2009, P198 ~, Appendix 7

  From the background described above, it is not easy to evaluate transformers and electrical equipment used in the field in any of the conventionally known mini electrostatic tester method and accumulated charge density method, and it is a method different from the conventional method, There is a need for the development of a test method that can be used to evaluate the insulating liquid and solid insulation of transformers currently in use.

  Accordingly, an object of the present invention is to provide a diagnostic method capable of evaluating the state of fluid charging in an electric device while taking into account the state of the insulating liquid and the solid insulator of the electric device such as a transformer used in the field. To do.

The flow charge evaluation and diagnosis method of the present invention is a flow charge evaluation and diagnosis method for an electric device in which a solid insulator is immersed in an insulating liquid, and the insulating liquid collected from the electric device in operation and its insulating property It is characterized in that fluid charge is evaluated by charging solid insulating fine particles contained in a liquid.
In the present invention, an insulating liquid containing the solid insulating fine particles collected from the electrical equipment in use is caused to flow through a liquid circulation channel, and a metal filter provided in the middle of the liquid circulation channel is used to store the insulating liquid in the insulating liquid. It is preferable to evaluate the flow charge by collecting the solid insulating fine particles and measuring the generated charge density generated in the metal filter with an ammeter connected to the metal filter.

In the present invention, an insulating liquid collected from the electrical equipment in use is stored in a container, and the insulating liquid in the container is continuously supplied to the liquid circulation path to be circulated, and the insulating filter is supplied to the metal filter. The solid insulating fine particles in the conductive liquid are continuously collected, the generated charge density is measured over time by the ammeter, and the flow charge is evaluated from the value of the generated charge density measured over time. It may be a fluid charging evaluation diagnostic method.
In the present invention, an insulating liquid containing the solid insulating fine particles collected from the electrical equipment in use is allowed to flow through a vertically extending flow path, and the flow from the positive electrode and the negative electrode provided on the left and right sides of the flow path. A method may be used in which an electric field is applied to the solid insulating fine particles descending the path, and the flow charge is evaluated according to the moving direction of the solid insulating fine particles.
In the present invention, a bifurcated branch channel is provided below the channel extending vertically, the positive electrode and the negative electrode are installed on the left and right of the channel above the branch channel, and the positive electrode and the negative Observing the situation where the solid insulator particles move to the branch flow path by the electric field applied by the electrode, and grasping the number of movements of the solid insulator particles to the branch flow path side to evaluate the flow charge, The method to do is also good.

  The flow electrification evaluation diagnostic apparatus for electrical equipment according to the present invention is a flow charge evaluation diagnosis apparatus for electrical equipment in which a solid insulator and a current conductor are immersed in an insulating liquid, and stores the insulating liquid collected from the electrical equipment. An insulating liquid connected to the container, a circulation pump for sending the insulating liquid in the container to the circulation flow path and returning it to the container, and a middle of the circulation flow path And an ammeter connected to the metal filter and measuring a generated charge density through the metal filter.

  The flow electrification evaluation diagnostic apparatus for an electrical apparatus according to the present invention is a flow charge evaluation diagnostic apparatus for an electrical apparatus in which a solid insulator and a current conductor are immersed in an insulating liquid, wherein the flow path extends in the vertical direction. An introduction pipe for injecting an insulating liquid containing the solid insulating fine particles collected from the electrical equipment in use, a positive electrode and a negative electrode installed on the left and right of the introduction pipe, and the introduction pipe And a bifurcated branch pipe connected to the lower end portion of the tube.

When an insulating liquid is collected from an electrical device in operation, the insulating liquid contains solid insulating fine particles. In an electric device, a part of the surface of the solid insulator becomes fine particles and is discharged into the insulating liquid over time by energization of the energizing body. The amount of the fine particles released changes with time depending on the energization state and use state of the electric equipment. And the state in which the flow electrification occurs in the electrical equipment containing the insulating liquid has a correlation with the deterioration state of the solid insulator and the insulating liquid. For this reason, by grasping the state accompanying charging of the solid insulating fine particles in the insulating liquid, it is possible to evaluate the generation of flow charge in the electric device in use.
When diagnosing the occurrence of flow electrification by charging solid insulator particles, the metal filter collects the solid insulator particles while flowing the insulating liquid containing the solid insulator particles, By measuring the generated charge density with a connected ammeter, it is possible to evaluate the easiness of flow charge generation even in an electric device in use.

1 shows a transformer that is an example of a subject for performing flow electrification evaluation diagnosis according to the present invention, where (A) shows an overall configuration diagram of the transformer, and (B) shows an iron core and a coil housed inside the transformer. FIG. BRIEF DESCRIPTION OF THE DRAWINGS An example of the apparatus which performs the flow charge evaluation diagnosis based on this invention is shown, (A) is a whole block diagram of a flow charge evaluation diagnostic apparatus, (B) is a fragmentary sectional view which shows a metal filter installation part. The fragmentary sectional view which shows the structure before and behind the metal filter installation part provided in the apparatus. The graph which shows an example of the measurement result of the charging degree calculated | required with the same apparatus. The block diagram which shows the other example of the apparatus which performs the flow charge evaluation diagnosis based on this invention. 3 is a graph showing generated charge density and tan δ measured over time by heating the insulating liquid to 95 ° C. using the fluidized charge evaluation / diagnosis apparatus shown in FIG. 2.

<First Embodiment>
Hereinafter, the case of performing the fluid charging evaluation diagnosis according to the present invention will be described with reference to the drawings, taking an oil-filled transformer as an example.
FIG. 1 shows an example of the structure of an oil-filled transformer. In the oil-filled transformer 1 of this example, a plurality of coil bodies 3 are accommodated inside a tank 2 with their central axes facing up and down. Is filled with insulating oil. An iron core 5 made of a magnetic material such as a silicon steel plate is inserted through the central portion of each coil body 3, and each iron core 5 is integrated with an upper iron core 6 made of a magnetic material such as a silicon steel plate at the upper and lower ends.
A frame-shaped clamp part 7 is provided so as to surround both ends of each iron core 5 and the periphery of the upper iron core 6, and a clamp 8 is extended and formed on the upper and lower clamps 7. The coil bodies 3 are sandwiched from above and below, and a tightening force is applied to each coil body 3.

In this embodiment, the coil body 3 includes an outer coil 9 and an inner coil 10 as shown in FIG. 1B, and the outer coil 9 moves a winding (electrically conductive body) 11 and an insulating spacer (solid insulator) 12 up and down. The stacked body is sandwiched between the upper insulator 13 and the lower insulator 15. The inner coil 10 is configured by sandwiching a laminated body in which a winding (electrical conductor) 16 and an insulating spacer (solid insulator) 17 are vertically stacked between an upper insulator 18 and a lower insulator 19.
By sandwiching the upper insulators 13 and 18 and the lower insulators 15 and 19 with the upper and lower clamping brackets 8, a clamping force is applied to each coil body 3 from above and below, and in this state, the coil bodies 3 are immersed in insulating oil. ing.

Since the transformer 1 having the above-described configuration is used for the purpose of stepping down a high voltage sent from a power transmission line or the like near a power user, the winding 11 (electrical conductor) included in the outer coil 9 and the inner coil 10 is used. , 16 (conducting body) is constantly supplied with current. Since an electromagnetic force acts by passing a current through the windings 11 and 16, the electromagnetic force acts on the coil body 3 and the iron core 5, and these vibrate.
In addition, when a short circuit accident or a ground fault occurs in the transmission line, a large current that reaches 10 to several tens of times the rated load current may flow through the windings 11 and 16 of the transformer 1. Forces and vibrations can act.
Insulating spacers 12 and 17 which are aggregates of insulating paper and insulating paper wound around 9, 10, 11 and 16 on which these tightening forces and vibrations are always applied, insulating materials 13, 15, 18 and 19, iron core 5 and coils 3 from the insulator (not shown) that separates the coil 3 and the insulator (not shown) that separates the coil 9 and the coil 10, some of the fibers constituting the insulating paper become fine particles and are separated into the insulating oil over time. Come.
On the other hand, the insulating oil of the transformer 1 gradually deteriorates with time due to various factors.
The inventor of the present application assumed that the degree of progress of the deterioration of the insulating oil and the state of the fine particles of the fibers released from the insulating paper into the insulating oil represent the ease of generating the flow charge of the transformer 1.
Therefore, a part of the insulating oil containing fiber fine particles is collected for evaluation and diagnosis from the transformer 1 in actual use, and diagnosed by the fluidized charge evaluation and diagnosis device described below, thereby the transformer in actual use. In 1, it is possible to diagnose the ease of occurrence of flow charge.

FIG. 2 (A) shows an embodiment of a fluid charge evaluation diagnostic apparatus. A fluid charge evaluation diagnosis apparatus 30 of this embodiment includes a container 32 for storing insulating oil 31 collected from the transformer 1, and a container A circulation flow path 33 connected to 32, a circulation pump 35 incorporated in a part of the circulation flow path 33, a static electricity generation part 36 incorporated in a part of the circulation flow path 33, and a static electricity generation part 36 The connected ammeter 37 is mainly used.
A heater 38 is wound around the peripheral surface of the container 32, and the heater 38 is connected to a power supply (not shown), and the insulating oil 31 in the container 32 can be heated to a target measurement temperature by the heat generated by the heater 38. It is like that.

A lid 39 is detachably attached to the opening of the container 32, and a lead pipe 40 and a return pipe 41 are provided so as to penetrate the lid 39 up and down and reach the insulating oil 31 in the container. .
A circulation pump 35 is incorporated in the middle of the extraction pipe 40, and an annular flow path 43 is connected to the external terminal side of the extraction pipe 40 via a first three-way valve 42. The annular flow path 43 includes a first pipe line 43A connected to one port of the first three-way valve 42, and a second pipe connected to the first pipe line 43A via a second three-way valve 45. Path 43B and a third pipe 43C connected to the second pipe 43B via a static electricity generator 36. The terminal side of the third pipe 43C is connected to another port of the first three-way valve 42. Has been. Further, the relay pipe 46 is connected to one port of the second three-way valve 45, and one end of the return pipe 41 is connected to the terminal end side of the relay pipe 46 via the velocimeter 47.

In the above-described structure, the extraction pipe 40, the return pipe 41, the annular flow path 43, the first and second three-way valves 42 and 45, and the relay pipe 46 constitute the circulation flow path 33.
The insulating oil 31 is extracted from the container 32 through the extraction pipe 40 by the circulation pump 35, sent to the first three-way valve 42 side, and passed through the static electricity generating part 36 through the third pipe 43C to the second pipe 43B side. The insulating oil 31 can be sent to the container 32, the insulating oil 31 can be sent to the return pipe 41 via the second three-way valve 45, and the insulating oil 31 can be returned to the container 32.

  The static electricity generation unit 36 is provided between the upper holder 50 and the lower holder 51, and the joint type upper holder 50 connected to the second pipe line 43B and the joint type lower holder 51 connected to the third pipe line 43C. It consists of a disk-shaped metal filter 53 sandwiched through a seal ring 52. A connection port 50 a for connecting to the second pipe line 43 </ b> B is formed on the upper side of the upper holder 50, and a downwardly expanding widening path 50 b is formed on the inner bottom side of the upper holder 50. A connection port 51 a for connecting to the third pipe line 43 </ b> C is formed on the lower side of the lower holder 51, and an upwardly expanding widening path 51 b is formed on the inner upper side of the lower holder 51. The hole diameter (pore size; eye roughness) of the metal filter 53 is set to about 50 μm.

Since the metal filter 53 is provided so as to be sandwiched between the expansion path 50b of the upper holder 50 and the expansion path 51b of the lower holder 51, the insulating oil 31 flows from the third pipeline 43C to the second pipeline 43B side. The fine particles of the fibers contained in the insulating oil 31 are supplemented by the metal filter 53.
The insulating spacers 12 and 17, the insulators 13, 15, 18, and 19, the insulator that separates the iron core 5 and the coil 3, and the insulator that separates the coil 9 and the coil 10 are provided in the transformer 1 described above. Is made of coniferous pulp, and its fibers are 20-50 μm long and about 2 μm thick. Therefore, the coarseness of the metal filter 53 is made up of fine particles of fibers of the above size. The size is set so that it can be collected.
An opening / closing valve 55 is incorporated in the second pipeline 43B above the upper holder 50, and an opening / closing valve 56 is incorporated in the third pipeline 43C below the lower holder 51.

  A detection line 37 a that penetrates the inside of the lower holder 51 and is connected to the metal filter 53 is provided. An ammeter 37 is connected to the detection line 37 a that extends to the outside of the lower holder 51, and the ammeter 37 is It is grounded via the ground line 37b. The ammeter 37 is provided for detecting the electric charge accumulated in the metal filter 53.

Inside the container 32, an electrode 60 for measuring tan δ of insulating oil is provided immediately below the lower end of the extraction pipe 40, and a measuring device connected to the electrode 60 via a wiring 61 penetrating the lid 39 on the side of the container 32. 62 is provided.
In addition, a supply pipe 63 that penetrates the lid 39 and communicates with the space below the lid 39 is provided, and an air supply source is connected to the supply pipe 63 via a desiccant container 65 such as silica gel. A nitrogen gas supply source is connected to 63 via an oxygen trap 66.

Next, an example in which the flow charge diagnosis is performed using the flow charge evaluation diagnostic apparatus 30 shown in FIG. 2 will be described.
In the configuration shown in FIG. 1A, a necessary amount of insulating oil is extracted from the transformer 1 in use. An amount of insulating oil necessary for diagnosis can be collected from the inside of the tank 2 through a valve provided in the tank 2 of the transformer 1.
If the transformer 1 is continuously used, the coil 11 or 16 including the windings 11 and 16 is energized by the electromagnetic force generated by the windings 11 and 16 when the windings 11 and 16 which are current conductors are energized. Vibration occurs. Further, the insulating spacers 12, 17, the insulators 13, 15, 18, 19 and the insulator that separates the iron core 5 from the coil 3 and the insulator that separates the coil 9 from the coil 10 are made of insulating paper. Factors such as being exposed to current flow, being vibrated by the effects of energization or electromagnetic force, or being affected differently by the occurrence of short circuits or ground faults. A part of the fiber is peeled off and released into the insulating oil as fine particles.
When the insulating oil is collected from the transformer 1 in use, the insulating spacers 12 and 17, the insulators 13, 15, 18 and 19, the insulator that separates the iron core 5 and the coil 3, the coil 9 and the coil are contained in the insulating oil. Part of the fibers constituting the insulator separating 10 is inevitably mixed as fine particles.

A required amount of insulating oil 31 collected from the transformer 1 in use is put into a container 32 of the apparatus shown in FIG. 2 in an airtight state, and the opening of the container 32 is closed with a lid 39. Further, when the opening of the container 32 is closed by the lid 39, only the nitrogen gas is fed into the upper space of the container 32 with the lower end of the supply pipe 63 positioned above the oil surface position of the insulating oil 31 to perform nitrogen sealing.
Next, the circulation pump 35 is operated to suck up the lubricating oil 31 from the container 32 and send it to the annular flow path 43. In the annular flow path 43, the insulating oil flows from the third flow path 43 </ b> C toward the static electricity generation unit 36, so that the insulating oil 31 passes through the metal filter 53 and then returns to the container 32 via the return pipe 41.
When this operation is repeated for a predetermined time, a minute amount of fine particles contained in the insulating oil are sequentially captured and accumulated on the lower surface side of the metal filter 53.

The trapped fine particles come into contact with oil and flow charge and charge flows through the metal filter 53, and this charge can be measured by the ammeter 37. If the above-described circulating operation of the insulating oil is performed for a predetermined time, charging continues because the oil continues to flow, and the charge density can be measured sequentially. The measurement time can be several hours to several hundred hours.
The temperature of the insulating oil is heated and held at, for example, about 50 ° C. by the heater 38, and the charge density is measured by setting the flow rate of the insulating oil 31 to a constant value, for example, about 5 cm / s. By this measurement, the amount of charge generated at a rate of several pC / mL can be measured.

As the surface area of the paper fiber in contact with the insulating oil is larger, the amount of charge generated by flow electrification is considered to increase. Therefore, the number, average length, and average width of the paper fibers captured by the metal filter 53 are measured with a fiber shape measuring instrument. Then, after calculating the surface area, calculate the charge generated per unit paper area (generated charge density, unit [pC / mL / mm ² ]), and based on this value, it is easy to charge between insulating oil and paper fiber Can be evaluated.
If this generated charge density is measured with insulating oil of a plurality of transformers and accumulated as information for each transformer, what level of generated charge density is likely to cause flow charging, I can grasp it.
For example, when the generated charge density is about 1 to 10 [pC / mL / mm ² ], it can be understood that the transformer is a transformer in which flow electrification hardly occurs. As information that can be estimated and grasped by utilizing measurement information such as a conventionally known mini electrostatic tester method, the generated charge density measured by the flow charge measuring device of this embodiment is several hundred [pC / mL / mm ² ]. At the level, it can be estimated that there is a high risk of flow charge generation in the transformer.

According to the flow charge evaluation and diagnosis apparatus 30 shown in FIG. 2, the insulating oil necessary for the evaluation is extracted from the transformer 1 in use, and the charged state of the fine particles of the fibers contained in the insulating oil is measured by the ammeter 37. Therefore, it is possible to diagnose and evaluate the ease of flow charging of the insulating oil accommodated in the transformer 1 in use without stopping the transformer 1 and without disassembling the transformer 1.
Further, according to the fluidized charge evaluation / diagnosis apparatus 30, the temperature of the insulating oil in the container 32 can be measured after adjusting with the heater 38. Therefore, it is possible to diagnose the ease of flow charge generation according to the temperature of the insulating oil. In addition, by setting the temperature of the insulating oil to a high temperature and measuring the charge of the metal filter 53, it is possible to perform an acceleration test as in the examples described later to determine the ease of fluid charge generation of the insulating oil.

Second Embodiment
FIG. 5 shows a second embodiment of the flow charge evaluation and diagnosis apparatus according to the present invention. A flow charge evaluation and diagnosis apparatus 70 according to the second embodiment includes an introduction pipe 71 extending in the vertical direction, Bifurcated branch pipes 72 and 73 connected to the lower end portion of the introduction pipe 71, a positive electrode 75 and a negative electrode 76 which are arranged on the side wall of the lower end portion of the introduction pipe 71 so as to be opposed to each other on the left and right, Mainly a power source 77 connected to the electrode 75 and the negative electrode 76.

In the fluid charging evaluation diagnostic apparatus 70, the introduction pipe 71 is vertically supported by a clamp member 78, the clamp member 78 is supported by a support 80 via a muff member 79, and the support 80 is erected on a stand 81. The introduction pipe 71 is supported in a vertical direction, and the branch pipes 72 and 73 are arranged at an inclination angle of 120 ° with respect to the introduction pipe 71. Therefore, the introduction pipe 71 and the branch pipes 72 and 73 are arranged in an inverted Y shape when viewed from the side.
The introduction pipe 71 has a structure in which an upper pipe 71a and a lower pipe 71b are added, and an opening 71c for supplying insulating oil is formed at the upper end of the upper pipe 71a.
The power source 77 is a power source that can apply a DC voltage of about several hundred volts DC, for example, about 500 volts DC, to the positive electrode 75 and the negative electrode 76.

The flow charge evaluation and diagnosis apparatus 70 of the second embodiment mixes the fiber fine particles of insulating paper in the insulating oil, and stirs the insulating fiber and the insulating oil by stirring and settles along the insulating oil in the introduction pipe 71. The ratio of the insulating fibers moved to the branch pipe 73 and the insulating fibers moved to the branch pipe 73 by applying electrostatic fields from the positive electrode 75 and the negative electrode 76 to the settled insulating fiber fine particles and depending on the charged state of the insulating fibers It is a device that performs flow charge diagnosis according to the above. During charging, the oil is charged positively and the insulating fiber is charged negatively.
For this reason, the flow charge diagnosis can be performed by measuring (number of insulating fibers in the branch pipe 72) / (number of insulating fibers in the branch pipe 73). Since the branch pipe 72 is close to the positive electrode 75 and the branch pipe 73 is close to the negative electrode 76, the insulating fibers are charged negatively. Therefore, a large amount of the insulating fibers are collected on the branch pipe 72 side.
If the ratio is a value close to 1.0, it can be estimated that the number of charged insulating fibers is small or the amount of charge is small. It can be determined that it is difficult to occur. If the ratio is a large value away from 1, it can be determined that fluid charging is likely to occur in the fluid charging diagnosis of the transformer from which the insulating oil has been recovered.

<First embodiment>
A metal filter having a pore size (pore size) of 50 μm was prepared, and this metal filter was sandwiched between an upper holder and a lower holder of the fluid charging evaluation diagnostic apparatus shown in FIG.
Primary voltage 275kV, secondary voltage 56kV, rated capacity 190MVA, oil-filled power transformer made in 2000, oil for 10L is taken from the transformer used for 15 years, the fibers are collected, and flow charging The ease of occurrence was diagnosed.
1.3L of insulating oil is contained in a container, the temperature of the insulating oil in the container is adjusted to 50 ° C, and the insulating oil is circulated with a circulation pump so that the flow rate in the circulation channel is 5.3cm / s. The flow charge was measured. Note that the wide joint type upper holder 50 and the lower holder 51 shown in FIG. 2B are schematic views, and the shaft joint type upper holder 50 and the lower holder 51 shown in FIG. The test was conducted using a holder having a structure in which a metal filter 53 was provided therebetween. A pipe made of polytetrafluoroethylene is incorporated in the middle of the pipe on the upper side of the holder, and a pipe made of polytetrafluoroethylene is also incorporated in the middle of the pipe on the lower side.
When collecting the insulating oil from the transformer, it is not desired to oxidize the insulating oil as much as possible. Therefore, when the insulating oil is collected in a container such as a tin can, the joint-type holder is connected to the on-off valve 55 in the middle of the sampling pipe. , 56 and used as an intermediate pipe for collection. After collecting the insulating oil from the transformer, the holders can be removed from the pipes for the portions of the on-off valves 55 and 56, and the apparatus shown in FIG. When incorporated in the apparatus of FIG. 2, the metal filter 53 is electrically floated by upper and lower polytetrafluoroethylene pipes. Of course, the insulating oil may be collected directly from a transformer into a container such as a tin can without using this holder.
The test results are shown in FIG.

As shown in FIG. 4, this insulating oil had a charge generation amount of about 4.2 pC / mL. The number of paper fibers on the metal filter, the average length, and the average width are measured with a fiber shape measuring instrument to determine the surface area, and then the charge generated per unit paper area (generated charge density) is calculated. The ease of fluid charging between the insulating oil and the paper fiber was evaluated.
The surface area of the insulating paper fiber was determined to be 1.84 [mm ² ], and the generated charge density was determined to be 2.28 [pC / mL / mm ² ].
This generated charge density is a sufficiently low value, and it was diagnosed that the transformer is a transformer in which flow electrification hardly occurs.

<Second embodiment>
Using another insulating oil recovered from the transformer used in the first embodiment, only the insulating oil obtained by partially filtering this insulating oil and removing the insulating fiber fine particles is obtained from the branch pipes 72 and 73 of the apparatus shown in FIG. After injecting halfway through the introduction pipe 70, the insulating oil containing the insulating fiber fine particles was then injected into the upper pipe 71 a of the introduction pipe 71. That is, the insulating oil that was not filtered after being taken out from the transformer was poured while being stirred for a certain period of time.
A DC 500 V power source was connected to the positive electrode and the negative electrode, and an electrostatic field was applied from each electrode to the lower side of the introduction tube 70.

Since the insulating fiber fine particles are contained in the insulating oil on the upper side of the introduction pipe 70, the insulation fiber fine particles settle inside the introduction pipe 70 due to gravity, and are electrically charged by the electrostatic field according to the charged state. The fine particles of the fibers settle to move toward the branch pipe 72, and the fine particles of the insulating fibers that are not charged or have a small charge amount settle to move toward the branch pipe 73.
When the ratio of the number of insulating fiber fine particles settled on the branch pipe 72 and the number of insulating fiber fine particles settled on the branch pipe 73 side was measured with a fiber shape measuring device, the ratio was 1.05, which is close to 1.0 and a small value. Met. For this reason, it can be diagnosed that the previous transformer is a transformer in which flow electrification hardly occurs.

<Example 3>
Using another insulating oil recovered from the transformer used in the first example, a heating deterioration acceleration test was performed using the fluid charging evaluation diagnostic apparatus shown in FIG.
Bare copper foil as a catalyst is mixed with 0.5 cm ^{2 of} 1.0 L of insulating oil in the insulating oil in the container of the fluid electrification evaluation diagnostic apparatus, nitrogen gas is supplied into the container and nitrogen is sealed, and the container is insulated. The oil was heated to 95 ° C. and heated for 190 hours to accelerate degradation. Assuming that the average oil temperature is 45 ° C, the temperature increase of 95 ° C-45 ° C = 50K is about 141 accelerating as a half rule of 7 ° C, and heating for 190 hours is 190 hours × 141 = 26790 hours = about 3 years Such deterioration was simulated.

FIG. 6 shows the results of continuous measurement of the generated charge density and tan δ during the 95 ° C. accelerated heating test. The generated charge density and tan δ are measured with the temperature of the insulating oil set at 95 ° C. and the flow rate of the insulating oil set at 1.5 cm / s.
As a result, the generated charge density, which was about 6.3 [pC / mL / mm ² ] at the beginning of heating, increased to about 14 [pC / mL / mm ² ] by heating for 190 hours.
From this result, it can be estimated that the transformer used in this test has an increased risk of generating flow electrification in the future, but the risk increase tends to slow down as shown in FIG. For this reason, it can be estimated that the insulating oil used in this test is an insulating oil that can withstand long-term use.
On the other hand, as shown in FIG. 6, tan δ increases linearly with time. This measurement result suggests that the oxidative deterioration of the insulating oil is gradually progressing, and that the generated deterioration products increase tan δ, and that tan δ needs to be continuously monitored. ing.

  DESCRIPTION OF SYMBOLS 1 ... Transformer, 2 ... Tank, 3 ... Coil body, 5 ... Iron core, 6 ... Upper iron core, 7 ... Fastening member, 8 ... Fastening metal fitting, 9 ... Outer coil, 10 ... Inner coil, 11, 16 ... Winding ( (Electrical conductor), 12, 17 ... insulating spacer (solid insulator), 30 ... fluid charging evaluation diagnostic device, 31 ... insulating oil, 32 ... container, 33 ... circulating flow path, 35 ... circulating pump, 36 ... static electricity generating part, 37 ... Ammeter, 38 ... Heater, 40 ... Drawer tube, 41 ... Return tube, 50 ... Upper holder, 51 ... Lower holder, 53 ... Metal filter, 70 ... Fluid charge evaluation diagnostic device, 71 ... Introduction tube, 72, 73 ... Branch pipe, 75 ... Positive electrode, 76 ... Negative electrode, 77 ... Power supply.

Claims (6)

A fluid charging evaluation diagnostic method for electrical equipment in which a solid insulator is immersed in an insulating liquid,
A fluid charging evaluation diagnostic method for an electrical device, wherein the fluid charging is evaluated by charging an insulating liquid collected from the electrical device in operation and solid insulating fine particles contained in the insulating liquid.   An insulating liquid containing the solid insulating fine particles collected from the electrical equipment in use is caused to flow through the liquid circulation channel, and the solid insulator in the insulating liquid is provided by a metal filter provided in the middle of the liquid circulation channel. The flow charge of an electric device according to claim 1, wherein the flow charge is evaluated by collecting fine particles and measuring a generated charge density generated in the metal filter by an ammeter connected to the metal filter. Evaluation diagnostic method.   Insulating liquid collected from the electrical equipment in use is stored in a container, and the insulating liquid in the container is continuously supplied to the liquid circulation path and circulated, and the metal filter contains the insulating liquid in the insulating liquid. 3. The solid insulator fine particles are collected, the generated charge density is measured over time by the ammeter, and the flow charge is evaluated from the value of the generated charge density measured over time. Method for evaluating the flow charge of electrical equipment.   An insulating liquid containing the solid insulating fine particles collected from the electrical equipment in use is caused to flow in a channel extending vertically, and descends from the positive electrode and the negative electrode provided on the left and right sides of the channel. 2. The method for evaluating the flow charge of an electric device according to claim 1, wherein an electric field is applied to the solid insulator fine particles, and the flow charge is evaluated according to a moving direction of the solid insulator fine particles.   A fluid charging evaluation diagnostic apparatus for an electrical device in which a solid insulator and a current conductor are immersed in an insulating liquid, the container storing the insulating liquid collected from the electrical device, and the insulating property connected to the container A liquid circulation channel, a circulation pump for sending the insulating liquid in the container to the circulation channel and circulating it back to the container, a metal filter provided in the middle of the circulation channel, and the metal filter A flow electrification evaluation diagnostic apparatus for an electric device comprising an ammeter connected to measure the generated charge density via the metal filter. A fluid charging evaluation diagnostic apparatus for electrical equipment in which a solid insulator and a current conductor are immersed in an insulating liquid,
An inlet pipe that constitutes a flow path extending in the vertical direction and injects an insulating liquid containing the solid insulating fine particles collected from the electrical equipment in use, and a positive pipe installed on the left and right of the inlet pipe. A fluid charging evaluation diagnostic apparatus for an electric device, comprising: an electrode, a negative electrode, and a bifurcated branch pipe connected to a lower end portion of the introduction pipe.

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