JPH1116741A - Static induction equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a static induction equipment against dielectric failures caused by flow charge by a method, wherein a porous low-charge member is provided to the surface of an insulating member where insulating liquid flows. SOLUTION: Flow changing rings 35 to 38 which enable insulating oil 7 flowing through a vertical cooling path 100B to flow through a horizontal fooling path 100A are provided to the inner circumferential surfaces of an insulating cylinder on a core 1 side and another insulating cylinder on a tank side respectively. Porous fluororesin layers 104, 111, and 112 of porous low- charge member are provided to the surfaces of insulating members near the inlets and outlets of the flow-changing rings 35 to 38 and provided to the inner circumference of an intermediate cooling hole as indicated by circles. The porous fluororesin layer is formed through such a manner that polytetrafluoroethylene(PTFE) films are pasted together. A PTFE pipe is of resistivity 10<14> (Ω.cm) in a current density range of 1 to 10 (pA/cm<2> ).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static induction device, in particular, to a structure in which a cooling passage is formed in a heating portion of a stationary induction device main body accommodated in a tank, and an insulating liquid is circulated by a pump through the cooler. In particular, it relates to a static induction device such as a high-voltage large-capacity transformer.

[0002]

2. Description of the Related Art In general, a static induction device such as an oil-filled iron-type transformer has a low-voltage winding around an iron core leg and a high-voltage winding concentrically arranged around the iron leg with a main insulation distance. When each winding is formed of a disc coil, the insulation is maintained by interposing a spacer between the coils, and a horizontal cooling passage for cooling the winding by circulating the insulating oil is secured. In addition, an insulating cylinder barrier and a linear spacer are arranged along the winding between the main insulations, and a vertical cooling passage for holding the insulation and cooling the winding is formed. In addition, a cooler and a pump are arranged outside the transformer main tank, connected by piping, and the insulating oil is circulated through the inside of the transformer winding.

In a circulation path, for example, a passage in a winding, charge separation occurs at a boundary surface between the insulating oil and the insulator, and the insulating oil has a positive charge and the insulator has a negative charge, so-called electrostatic charging occurs. The magnitude of the charge changes depending on the properties of the insulating oil, the places where the flow velocity is fast, and the surface condition of the insulator, but when the accumulated charge density increases, the electric field in that part increases, causing electrostatic discharge, and the AC voltage During the operation of the transformer, a dielectric breakdown accident progresses.

[0004] These are generally known as a flow charging phenomenon of a transformer, and are described in a literature (referred to as a known example 1), IEEJ, Vol. 99, p. 913, 1979 ("Flow charging phenomenon in a large capacity transformer"). Tamura et al.). In Japanese Patent Application Laid-Open No. 52-156335 (hereinafter referred to as "known example 2"), the edge and the bend of the insulator serving as an oil path to the transformer winding are provided with a roundness of 5 to 50 mm to cause electrostatic charging. The ones that are not included are described.

In Japanese Patent Application Laid-Open No. 53-15518 (hereinafter referred to as "known example 3"), an ether bond or a thioether is added to an electrically insulating paper serving as an insulator, or methyl cellulose, ethyl cellulose, polyethylene sulfide,
It describes a method of applying a mixture of polysulfide, ethylcellulose and polyether or the like, or formalizing an electric insulating paper to make the specific resistance of the electric insulating paper an appropriate value to suppress the accumulation of static electricity.

[0006]

In a large-capacity oil-filled transformer, it is necessary to increase the cooling efficiency in order to increase the capacity and reduce the size, and therefore it is necessary to increase the flow rate of the insulating oil for cooling. However, when the flow velocity is increased, the amount of static charge generated by the flow electrification increases, and the risk of discharge in oil increases. Even if the curved portion of the cooling duct is rounded to smooth the flow and the turbulence is suppressed as in the known example 2, even if the turbulence is suppressed, it is necessary to further increase the flow rate and to prevent electrostatic charging corresponding to a high flow rate. Not enough.

Further, as described in the known example 3, even if the surface treatment is performed so that no electric charge remains on the surface of the electrically insulating paper, there is no effect on the generation of the electric charge, and a large amount of the insulating fluid is used. It flows with excess charge, charge relaxation occurs in the slow flow areas, and the charge is accumulated, causing electrostatic charging. It is also conceivable to attach a material with low static charge generation to the oil passage surface with a high flow rate and a large amount of generated charge to suppress the amount of generated static electricity. Although the amount of generated electric charge is small, it has a disadvantage that the resistivity is very large, the generated electric charge is easily accumulated, and electrostatic discharge easily occurs.

An object of the present invention is to provide a stationary induction device which prevents an insulation accident due to flow electrification that occurs when an insulating liquid flows through an insulator at high speed.

[0009]

In order to achieve the above-mentioned object, a static induction device according to the present invention comprises a tank in which an iron core and a winding in which a conductor attached to the iron core is covered with an insulating member are housed. Pipes communicating between the cooler and the tank arranged outside and the pumps provided in these are operated to circulate the insulating liquid between the tank and the cooler to cool the iron core and windings , A porous low-charge member is provided on the surface of the insulating member through which the insulating liquid flows.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIGS.
This will be described with reference to FIG. FIG. 1 shows a configuration of a transformer according to one embodiment of the present invention. A winding 2 is wound concentrically around an iron core 1, an insulating cylinder 3 is provided outside the winding 2, and the transformer is fixed to a flow rate adjusting plate 14. ing. The iron core 1 is fastened and fixed by a lower common cooling passage 12 and an upper fastener 13 and housed in a tank 4. In addition, a conservator 5 is provided on the upper part of the tank 4,
An insulating oil 7 as an insulating liquid is filled up to the partition film 6 in communication with the tank 4. The partition film 6 responds to the expansion and contraction of the insulating oil 7, and fills a gas into the upper surface thereof to adjust the pressure.

From the side of the tank 4, the upper pipe 10
And the lower pipe 11 are led out, connected to the cooler 8 and the circulation pump 9, and the flow of the insulating oil 7 is indicated by the arrow as the circulation pump 9 → the lower pipe 11 → the common cooling passage 12 → the winding 2 → the upper part is tightened. The insulating oil 7 is circulated from the metal fitting 13 to the upper pipe 10 to the cooler 8. Although the flow of the liquid on the surface of the iron core 1 is not shown, a passage is provided between the winding 2 and the iron core, and a passage is provided in the iron core to cool the iron core 1.

FIG. 2 is an enlarged sectional view of a lower portion of the winding 2 of FIG. The winding 2 is formed by stacking a plurality of disc coils 25 and disc coils 26, and the inner peripheral disc coil 2
A horizontal cooling passage 100A is formed between 5 and 25, and the horizontal cooling passage 100A between the disk coils is supported by a spacer (not shown). Also, the outer-side disk coils 26 and 26
A horizontal cooling passage 100A is also formed between them. The transformer oil enters the common cooling passage 12 from the lower pipe 11, and flows between the insulating ring 131 and the insulating cylinder 32, and the insulating ring 13.
3 and the insulating tube 33 flows upward, and the disk coils 25, 2
Flow to 6.

The disk coil 25 and the disk coil 26 are respectively connected to the inner insulating cylinders 31 and 32 and the outer insulating cylinder 3.
3 and 34, a plurality of disk coils 2 communicating with the horizontal cooling passage 100A and corresponding to the insulating cylinders 31 to 34.
Vertical cooling passages 100B are formed along the stacking directions of the cooling layers 5 and 26. Insulating cylinders 32 to 3 are formed so that flow paths 35, 36, 37 and 38 are prevented from flowing through vertical cooling passage 100B.
3 at predetermined intervals and apply insulating oil 7 to a plurality of disc coils 2
The flow in the winding is meandered as indicated by the arrows in each of the blocks 5 and 26 so that the cooling in the winding is uniform.

The flow rate of the insulating oil on the surfaces of the disk coils 25 and 26 increases as the flow rate increases in order to increase the cooling efficiency, and the charge separation easily occurs accordingly. Therefore, in the embodiment of the present invention, as shown in FIG. 3, the insulated wire constituting the disc coil is formed by winding the insulating paper 211 around the conductor 210 and winding the film 212 made of porous fluororesin on the outermost layer surface. It is composed. The reason why charge separation is unlikely to occur when a fluorine-based resin is used in a portion where the insulating oil 7 flows as described above will be described. When the porous fluororesin is observed with an electron microscope, a gap where the fibers 212A are entangled with each other can be referred to as a pore 212B. In other words, they are intertwined like a dried gourd.

That is, the charge amount was examined using a pipe model using the insulating oil 7 as an example of the insulating liquid. FIG. 4 shows the current density (pA / cm ² ) per unit area of the inner wall surface of the pipe when the insulating oil flows through the pipe, and the size changes depending on the pipe material. Among these, the one having the lowest current density is a polytetrafluoroethylene (hereinafter abbreviated as PTFE) pipe, which is a porous fluororesin, which is about the same as paper of a press board or the like constituting an oil passage of a normal transformer. It is 1/20. It is considered that the reason why the flowing current of the PTFE pipe is small as described above is that it is a nonpolar polymer material having no polar group in the molecule, and thus it is difficult for ions to be adsorbed. Current density of PTFE pipe (pA /
cm ² ) as long as the current density is in the range of 1 to 10 (pA / cm ² ). The reason for this is that if it is 10 (pA / cm ² ) or more, excessive current will flow excessively and the surface potential will rise too much,
Dielectric breakdown easily occurs. On the other hand, if the current density is 1 or less, it is not possible to use because of special production and high cost.

Next, the resistivity of the material in the oil immersion state (Ω.c)
m) are shown in FIG. FIG. 5 shows a comparison of representative values. Although the resistivity of PTFE is more than two orders of magnitude higher than the resistivity of oil immersion press board, porous PTFE
In the case of E, it is about two orders of magnitude smaller than the case of the oil immersion press board, and is comparable to insulating oil. If the resistivity of the porous PTFE is 10 ¹⁴ (Ω.cm), the flow current is small, and the resistivity is close to that of oil because of the porosity, so that charge separation hardly occurs and charge accumulation is difficult. In addition, electrostatic charging can be suppressed. The product of the resistivity and the flowing current density in FIG. 4 corresponds to the surface potential, which is shown in comparison with FIG. It can be seen that the PTFE has a surface potential value higher than that of the oil immersion press board, but the porous PTFE shows a value smaller than that of the press board by about one digit.

The reason why the surface potential of the porous PTFE is small is that the flowing current is small and the resistivity is close to that of oil due to the porous nature. Therefore, when a cooling device is connected to a stationary induction device to form a cooling path for circulating insulating oil with a circulating pump, a surface in contact with the insulating oil is formed of a porous flow-charging suppressing member, for example, a porous fluororesin. In this case, since charge separation hardly occurs and charge is hardly accumulated, electrostatic charging can be suppressed.

In FIG. 3 described above, the insulating paper 211 is attached to the conductor 210.
Is wound, and a film 212 made of a porous fluororesin is wound on the outermost layer surface, so that the insulating liquid flows into the insulating paper 211.
Is covered with a porous fluororesin film so that electric charge separation hardly occurs at the boundary surface thereof, electric charge is hardly accumulated, and electrostatic charging is suppressed. As the porous fluororesin film or sheet, a porous PTFE film or sheet obtained by uniaxially stretching or biaxially stretching is used. In addition, fine holes are formed by PTE using other methods.
It is possible to use an E film or a sheet that has been made porous by opening it.

As a specific example of the electric wire coating, even if a coil is formed by winding a porous fluororesin film in all layers, the effect of suppressing electrostatic charging is the same, but the liquid flow rate is slow and charge separation occurs. The part of the coil that is not used is a conventional insulated wire, and a part with a large turbulence or a part with a high flow velocity, for example, a porous fluorine resin film is coated only on the coil at the lower part of the winding that becomes the liquid inlet. In addition, electrostatic charging can be suppressed. Therefore, an inexpensive static induction device can be provided by partially applying the porous fluororesin film.

An insulating ring is provided on a common cooling passage communicating with the one-side pipe, and an intermediate cooling hole is provided between the common cooling passage and the insulating ring so that a part of the insulating ring communicates with the intermediate cooling hole. A vertical cooling passage formed in the stacking direction of the disc coils connected to the inner cooling tube and the outer insulating tube between the tank and the iron core, and formed in the horizontal cooling passage between the respective disc coils and the intermediate cooling holes. And a porous low-charge member is used on the surface of the insulating member between the inlet and outlet of the flow ring and the inner peripheral surface of the intermediate cooling hole.

For example, insulating rings 131 and 132 are arranged on the common cooling passage 12 communicating with the lower pipe 11 of FIG.
A cooling hole 120A is provided between the common cooling passage 12 and the insulating rings 131 and 133, and insulation on the inner peripheral side between the tank 4 and the iron core 1 is provided on the insulating ring so that a part thereof communicates with the intermediate cooling hole 120A. Cylinders 31 and 32 and insulating cylinder 3 on the outer peripheral side
3 and 34, a plurality of the above-mentioned disk coils 25 and 26 are laminated in both insulating cylinders, and the disk coils 25 and 26 communicate with the horizontal cooling passage 100A and the intermediate cooling hole 120A between the disk coils. And a vertical cooling passage 100B formed between the two insulating cylinders.

The flow-circulation rings 35 to 38 for flowing the insulating oil 7 in the vertical cooling passage 100B to the horizontal cooling passage 100A are formed on the inner peripheral surface of the core-side insulating cylindrical portion of both insulating cylinders and the inner peripheral surface of the tank-side insulating cylindrical portion. And the folding rings 35 to 38 indicated by circles.
The porous fluororesin layers 104, 111 and 112, which are porous low-charge members, are provided on the surface of the insulating member between the entrance and exit of the substrate and the inner peripheral surface of the intermediate cooling hole. In other words, the flow rings 35 to 38 for flowing the insulating oil 7 blocking the vertical cooling passage 100B on the iron core 1 side and the tank side to the horizontal cooling passage 100A are provided on the inner peripheral surfaces of both insulating cylinders. A porous low-charge member is provided on the surface of the insulating member between the inlet and outlet and the inner peripheral surface of the intermediate cooling hole. Needless to say, the present invention can be applied to a transformer using a single insulating cylinder.

As a result, it is possible to suppress the flow electrification at a place where the flow rate of the insulating oil 7 is higher, to enable high-speed liquid circulation, to perform high-efficiency cooling, and to use a conventional static electricity without using a porous PTFE film. The capacity of the static induction device of the present invention can be greatly increased as compared with the induction device.

FIG. 7 shows a specific structure of the insulating tube 32 shown in FIG. 2. A porous fluororesin film 320 is provided on the surface of the insulating tube 32 formed by molding a thick insulating paper board. The membrane 320 is formed by laminating a thin porous PTFE film.

FIG. 8 shows a specific configuration of the insulating ring 131 shown in FIG. 2. Insulating pieces 135 are arranged at predetermined intervals between insulating plates 136 to form the insulating ring 131. Further, the liquid flow rate adjusting plate 132 is disposed between the coil 2 and the insulating ring 131, and adjusts a protrusion size from the insulating ring 131 to adjust a liquid amount flowing to the upper coil. The surfaces of the insulating ring 131 and the liquid flow rate adjusting plate 132 are portions where the liquid flows at high speed, and the surfaces are covered with a porous fluororesin in order to reduce the amount of generated static electricity. That is, a porous PTFE film is bonded and configured. By using the porous PTFE film, the liquid impregnation property is not hindered, the charge accumulation is suppressed, and the electrostatic charge can be effectively suppressed.

FIG. 9 shows the structure of a transformer according to another embodiment of the present invention. The transformer main body composed of the iron core 1, the winding 2, the common cooling passage 12, and the upper fastener 13 is housed in an insulating container 21 having a rubber film 60 on the upper part, filled with insulating oil 7, and penetrates the tank 4 from the upper part. And pull out the upper pipe 10 and connect it to the cooler 8 to make the common cooling passage 1
2, the lower pipe 11 is drawn out through the tank and connected to the circulation pump 9, so that the insulating oil 7 is circulated as indicated by the arrow.

The insulating container 21 of the transformer constructed as described above.
Is an insulating oil 7 on the inner side, a gas side 50 on the outer side, and a portion where the liquid flows between the winding 2 and the inner side. Since the insulating container 21 requires a certain level of mechanical strength, the GFR
Made of P (glass fiber reinforced plastic). GFRP is a material having a high degree of charge, and is unsuitable as a material for an insulating container of a transformer from the viewpoint of suppressing flow charge. In this embodiment, the liquid side of the GFRP is covered with a porous fluororesin in order to reduce electrostatic charging.

FIG. 10 shows that a porous fluororesin layer 22 is provided inside an insulating container 21. The porous fluororesin layer 22 can be implemented by bonding a porous PTFE film. By doing so, charge separation inside the insulating container 21 can be suppressed, and electrostatic charging of the insulating container 21 can be reduced.

The insulating liquid applied to the present invention is not limited to transformer oil, but can effectively flow even if it is a perfluorocarbon liquid or a mixture of a perfluorocarbon liquid and another liquid such as perchlorethylene. The charge can be suppressed, and the flow charge can be suppressed by covering the contact surface with the liquid with a porous material having a small charge degree other than the fluororesin.

[0030]

As described above, according to the static induction device of the present invention, since the flow-charging suppressing member, for example, the porous PTFE film is disposed on the surface of the insulating member that comes into contact with the flowing insulating liquid, the circulation of the cooling liquid is achieved. The static induction device according to the present invention can suppress the flow electrification in the system and can perform high-speed liquid circulation, so that high-efficiency cooling can be performed and compared with the conventional static induction device not using a porous PTFE film. Capacity can be greatly increased. Further, it is possible to obtain a static induction device suitable for a high-voltage large-capacity transformer or the like which is highly reliable and does not cause an insulation accident due to flow electrification due to small electrostatic charging.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a stationary induction device according to an embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view of the vicinity of a winding used in FIG.

FIG. 3 is an enlarged perspective view of a winding used in FIG. 1;

FIG. 4 is a comparison diagram of flow charging characteristics of various materials of the stationary induction device.

FIG. 5 is a comparison diagram of the resistivity of various materials of the stationary induction device during oil immersion.

FIG. 6 is a comparison diagram of the flow charging characteristics of various materials of the stationary induction device.

FIG. 7 is a perspective view illustrating a configuration of an insulating cylinder according to another embodiment of the present invention.

FIG. 8 is a perspective view showing a configuration of an insulating ring according to another embodiment of the present invention.

FIG. 9 is an explanatory view of a stationary induction device according to another embodiment of the present invention.

FIG. 10 is a perspective view showing a configuration of an insulating container according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Iron core, 2 ... Winding, 3 ... Insulating cylinder, 4 ... Tank, 7
... insulating oil, 8 ... cooler, 9 ... circulation pump, 10 ...
Upper piping, 11: Lower piping, 22: Porous fluororesin layer, 212, 320 ... Porous fluororesin film.

Claims (5)

[Claims] 1. A tank containing an iron core and a winding in which a conductor attached to the iron core is covered with an insulating member in a tank, and a pipe communicating between a tank and a cooler disposed outside the tank, and a pipe connected thereto. The pump provided is operated to circulate the insulating liquid between the inside of the tank and the cooler to cool the iron core and the windings, etc., wherein a porous low-charge member is provided on the surface of the insulating member through which the insulating liquid flows. A static induction device characterized by comprising: 2. A pipe which accommodates an iron core and a disk coil in which a conductor attached to the iron core is covered with an insulating member in a tank, and which communicates between a tank and a cooler disposed outside the tank, and By operating the pump provided in the above, the insulating liquid is circulated between the inside of the tank and the cooler to cool the iron core and the winding, and an insulating ring is provided on a common cooling path communicating with one side pipe, An intermediate cooling hole is provided between the cooling path and the insulating ring, and an insulating cylinder is disposed between the tank and the iron core such that a part thereof communicates with the intermediate cooling hole on the insulating ring. The disk coils are stacked, and a horizontal cooling passage between the disk coils and a vertical cooling passage formed between an insulating cylinder and a stacking direction of the disk coils communicating with the intermediate cooling holes are provided. Block part of the vertical cooling passage on the side A folding ring for flowing in the flat cooling passage was provided on the inner peripheral surface of the insulating cylinder, and a porous low-charge member was provided on the insulating member surface near the inlet and outlet of the folding ring and the inner peripheral surface of the intermediate cooling hole. A static induction device characterized by the following. 3. The static induction device according to claim 1, wherein the porous low-charge member contains a fluorine-based resin. 4. The method according to claim 1, wherein said porous low-charge member is porous polytetrafluoroethylene.
Or the static induction device according to 2. 5. A current density of 1 to 10 (pA / p.m.) On the surface of the insulating member through which the insulating liquid flows as the porous low-charge member.
The static induction device according to claim 1 or 2, wherein a porous polytetrafluoroethylene having a resistivity of 10 < ¹⁴ > ([Omega] .cm) in a range of ² cm <2> is used.