JP2011066266A - Electromagnetic induction apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shield capable of improving insulation reliability with an iron core corner part, achieving clear grounding of the iron core with a small component structure, and relaxing an electric field, in an electromagnetic induction apparatus. <P>SOLUTION: In an iron core of this electromagnetic induction apparatus formed by laminating a plurality of metal plates each having an electric insulation coating applied to a surface thereof, this shield 7a for relaxing an electric field, mounted to each connection corner part between an electromagnetic induction apparatus iron core leg and iron core yokes 1a, 1b, 1c, 1d for relaxing an electric field comprises: a bendable insulation material; a conductive material arranged in the insulation material or on one surface thereof; and a grounding wire electrically connected to the conductive material, wherein the shield is arranged by being covered with a shape smoothly curved along an iron core corner part; the conductive material of the shield and both ends in the lamination direction of the electromagnetic induction apparatus iron core are grounded by the grounding wire; and electric field relaxation with a high-voltage charge part facing the vicinity and the grounding are achieved at the same time at both ends in the lamination direction of the electromagnetic induction apparatus iron core formed of the laminated metal plates, by the single shield. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a shield for relaxing an electric field attached to a corner of an iron core in an electromagnetic induction device.

  In general, an electromagnetic induction device such as a power transformer or a reactor includes an iron core leg, a winding, and an iron core yoke that magnetically connects the iron core legs as main elements. Many iron core legs and iron yokes used in transformers have a structure in which a plurality of thin metal plates having an electrically insulating coating on the surface are laminated.

  Therefore, as shown in FIG. 9a, the cross-sectional shape of the iron core is four corners 31a when stacked in a square shape, and when stacked in a circular shape, it has a stepped shape as shown in FIG. 9b. A corner portion 31b is formed in each of them, and both have a shape including the corner portion. Further, as shown in FIG. 8, a corner portion 31c is also formed at the joint portion between the iron core leg 2c and the iron core yoke 1c.

  That is, when the adjacent high-voltage lead wire 6 is disposed in the adjacent winding 4 or 31c with these 31a, 31b, a large potential difference is generated between each corner and the charging section, and corona discharge or insulation is caused. There is a risk of destruction.

  Therefore, conventionally, in such a place, an electric field is relaxed with a shield for reducing the electric field interposed therebetween, or the insulation of the lead wire is increased to improve the withstand voltage, and measures against these problems have been taken. In particular, in order to alleviate these electric field concentrations, a shield for reducing the electric field may be provided on the outer peripheral portion of the iron core leg (see Patent Document 1, Patent Document 2, and Patent Document 3).

  On the other hand, when the winding 4 is charged, a current temporarily flows toward the grounding point through the electrostatic capacitance existing between the winding 4 and the electromagnetic induction device core. Since this electric current flows in the stacking direction of the stacked metal plates in the iron core, a large potential difference is generated between the metal plates coated with the insulating coating. Further, since the insulating film does not exist in the portion where the metal plate is cut, the withstand voltage is lowered, and corona discharge or dielectric breakdown may occur.

  As countermeasures to prevent potential difference between the metal plates from increasing, insert grounding conductors at several locations between the laminated metal plates of the electromagnetic induction device core, or to resist the portion of the cut surface of the laminated metal plates where there is no insulation coating. Measures are taken to reduce the voltage by connecting the body (see Patent Document 4).

Japanese Patent Laid-Open No. 11-67557 JP-A-9-74029 JP 61-27613 A JP 58-165308 A

  However, since many members such as a shield, a resistor, a ground wire, and a connection terminal are required and a great deal of cost is required, a reduction in the number of parts has been demanded. In addition, as the number of parts increases, the size of the equipment is increasing, and at the same time, miniaturization is required.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a shield and an arrangement thereof for reducing electric field composed of a single component that simultaneously relaxes the electric field between the above-mentioned charging section and the core corner, and also performs grounding between the laminated metal plates. It is in.

  In order to achieve the above object, the present invention provides an electromagnetic induction device core configured by laminating a plurality of metal plates having an electrical insulating coating on the surface thereof, and a connection angle between the electromagnetic induction device core leg and the iron core yoke. A shield for reducing electric field attached to a portion, wherein the shield for reducing electric field is electrically connected to a bendable insulator, a conductor disposed inside or on one side of the insulator, and the conductor. The shield is covered with a smoothly curved shape along the corners of the iron core, and both ends of the shield conductor and the electromagnetic induction device iron core in the stacking direction are connected by a ground wire. And

  According to a second aspect of the present invention, there is provided an electromagnetic induction device core comprising a plurality of metal plates each having a surface coated with an electrical insulating film, wherein the electromagnetic induction device core is provided. A shield for electric field relaxation attached to a leg, wherein the electric field relaxation shield is electrically connected to a bendable insulator, a conductor disposed inside or on one side of the insulator, and the conductor. The shield is covered with a smoothly curved shape along the corners of the iron core legs, and both ends of the shield conductor and electromagnetic induction device iron core in the stacking direction are grounded with the ground wire. Features.

  As a result, a single shield can alleviate the electric field concentrated on the corners of the iron core, and withstand voltage with high-voltage windings and lead wires can be secured, preventing corona discharge and breakdown. . In addition, by connecting ground wires to both end faces of the electromagnetic induction device core in the stacking direction, the core can be clearly grounded, a large potential difference between the stacks can be reduced, and corona discharge generated between the metal plate end faces It is also possible to prevent dielectric breakdown.

  In other words, by arranging one shield for electric field relaxation according to the present invention, it is possible to simultaneously realize electric field relaxation and grounding that have been realized in many parts, and as a result, it is possible to reduce the number of members and downsize the equipment. It becomes possible.

It is a side view of the three-phase tripod iron core which shows Example 1 of this invention. It is sectional drawing of AA of FIG. FIG. 2 is a perspective view of a portion B in FIG. It is an expanded view of the invention product of FIG. It is a side view of the three-phase pentapod core which shows Example 2 of this invention. It is sectional drawing of the DD cross section of FIG. FIG. 6 is a development view of the product of FIG. 5. It is the schematic of a three-phase tripod iron core transformer. It is a laminated structure schematic of an iron core. FIG. 3 is a detailed view of part E in FIG. 2. It is a shield effect contrast diagram.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, the configuration of the shield 7a for reducing the electric field according to the present invention will be described. As shown in FIG. 4, the shield 7a is formed by laminating a plurality of insulators 33 (for example, press boards), and incorporating or attaching a conductive material therein or applying a conductive paint. A conductor 8a portion is provided. FIG. 4 shows an example in which a conductive material is incorporated inside. Further, a ground wire for reliably grounding is attached to both ends of the conductor 8a as a ground wire 10a. The conductive material 8a is preferably bonded to the insulator 33, but may be sandwiched between the insulators 33. The conductive material 8a may use other conductive materials such as other metal foils and conductive tapes. The size of the conductor 8a is smaller than that of the insulator 33 so as not to lower the withstand voltage.

  1, 2 and 3 show application examples of the first embodiment of the present invention. Example 1 is a case where the shield 7a of the present invention is applied to the joint corner portion 31c of the iron core leg 2 of the three-phase tripod iron core and the iron core yoke 1. As shown in FIG. 1, the three-phase tripod iron core has the windings 4 attached to the three iron core legs 2a, 2b and 2c, and the upper and lower ends of the tripod are magnetically connected by the iron core yokes 1a, 1b, 1c and 1d. It has a structure. Further, the iron core and the winding are clamped in the stacking direction of the iron core by the iron core clamp 5 and the fastening rod 12, and the vertical direction of the winding is held by the upper and lower fastening members 19, and the iron core and the winding are not displaced by the fastening rod 12. It is tightened like this.

  Next, the arrangement of the shield 7a for reducing the electric field according to the present invention will be described. As shown in FIG. 1, the shield 7a for reducing the electric field is disposed so as to face the high-voltage lead wire 6 and bend smoothly at the corner of the iron core. As described above, the shield is composed of several insulators 33, which can be easily bent and has a through insulation strength of the insulator 33, so that it is possible to secure a withstand voltage with respect to the power application section. . It is desirable that the shield 7a has a thickness corresponding to the working voltage in consideration of the penetration dielectric strength of the insulator. Of course, as long as the bending is possible, a molded insulator may be used instead of the stacked members.

  Next, the attachment of the shield 7a for reducing the electric field to the iron core will be described with reference to FIGS. First, attachment of the insulating support member 9a will be described. FIG. 2 is a cross-sectional view taken along a line AA in FIG. As shown in FIG. 2, an insulating support member 9a (for example, insulating wood) is inserted between the iron core and the shield 7a for reducing the electric field, and the insulating support member attached to the shield 7a for reducing the electric field is inserted. The hole 21 and the string 16a are tied and fixed, and the refrigerant is attached to the iron core while securing the flow path. The insulating support member 9a may be inserted only for the purpose of supporting the shield 7a for reducing the electric field when heat generation of the iron core is not a problem.

  Next, the connection between the ground wire and the iron core will be described. FIG. 10 shows details of the E part in FIG. FIG. 10 shows a method in which the insulating film is peeled off at both ends in the stacking direction of the metal plates and the shield grounding wire 10a for electric field relaxation according to the present invention is sandwiched between the metal plates and electrically connected. In this case, for example, the grounding wire 10a is formed by applying a conductive paint to a strip-shaped thin press board, and a part of the insulating coating 32 between the metal plates is peeled off and connected to the grounding wire 10a. Thereby, it becomes possible to electrically connect to the conductor 8a of the shield 7a for reducing the electric field. For connection, a general conductive adhesive or the like is used, but other methods may be used as long as electrical connection is possible.

  Finally, a method for fixing the shield 7a to the iron core for reducing the electric field will be described. The shield mounting hole 20 and the fastening rod 12 and the winding pressing member 19 are tied and fixed with a string 16b at a plurality of places. As shown in FIG. 1, the corners of the iron core are curved and smoothly covered. After determining the shape in this way, it is fixed with the string 16b.

  With the above configuration, since the ground wire connected to the shield conductor is connected to the end of the metal plate as described above, the conductor has a zero potential. Of course, it is assumed that the iron core is connected to ground. Therefore, the potential generated between the metal plates during operation decreases, and it becomes difficult for dielectric breakdown and corona discharge to occur at the end of the metal plate.

  Further, when the shield 7a for reducing the electric field is disposed at the iron core joint corner portion 31c, a member having a high dielectric constant is interposed between the high voltage lead wire 6 due to the shielding effect in the electric field, so that the electric field strength in the vicinity of the iron core corner portion 31c is increased. become weak. The electric field strength at the iron core corner portion 31c adjacent to the shield is shown in FIG. As can be seen from FIG. 11, the electric field is much relaxed compared to the case without a shield. In the case of the present invention, when the electric field strength was calculated, it was found that electric field relaxation of 40% or more could be realized at maximum by increasing the radius of curvature of the shield. That is, by arranging the shield so as to smoothly cover the iron core corner portion 31c, an effect is obtained in which the sharp corner portion is a curved surface having a large curvature radius.

  In other words, when trying to solve the grounding of the iron core and the electric field of the iron core corner portion 31c with the prior art, a plurality of resistors assembled to the metal plate and a shield for reducing the electric field are separately required. In addition, the attachment positions of these members are newly required in the equipment. This inevitably increases the size of the device. In the present invention, electric field relaxation and grounding can be realized at the same time with a single shield as described above, so the number of parts is minimized, and the number of parts is also small, so the installation space is also minimal, and the overall equipment is compact. Can also contribute to

  FIG. 7 shows a shield 7b for reducing the electric field according to the second embodiment. Since the basic structure of the shield 7b for reducing the electric field is the same as that of the shield 7a for reducing the electric field, overlapping portions are not described. As shown in FIG. 7, the shield 7b is structured to be wound around the iron core, and therefore, the place where the ground wire is attached is different from the shield 7a for reducing the electric field. In addition, no mounting holes are required for winding. The total length of the shield 7b for reducing the electric field needs to be at least long enough to wind the winding once. The other components are the same as the shield 7a for reducing the electric field.

  5, 6 and 7 show a second embodiment of the present invention. Example 2 shows the case where it applies to the side leg 3 of a three-phase five-legged iron core. Three-phase five-legged iron cores are often used for transformers with large capacities, and among the five legs, the inner tripod is the iron core leg to which the winding 4 is attached, and the outer two legs are the sides to which the winding 4 is not attached. Leg 3.

  In the case of the second embodiment, since the transformer capacity is large, the iron core fastener 5 is also large, and the joint corner between the side leg 3 and the iron yoke 1c may be hidden by the iron core fastener 5 as shown in FIG. However, when the protrusion of the iron core corner portion 31c becomes a problem, it is a matter of course that the shield for reducing the electric field as in the first embodiment can be applied. However, as described above, in a large transformer, it is necessary to take measures to alleviate the electric field at the corners of the metal plate of the iron core legs.

  FIG. 6 shows a cross-sectional view taken along the line DD in FIG. The shield 7b for reducing the electric field of the present invention is made to make one turn in the circumferential direction of the side leg 3, and is arranged so as to cover the laminated corner portion 31b. Furthermore, it electrically connects with the conductor 8b which the shield 7b which aims at electric field relaxation at the both ends of an iron core with the ground wire 10b. At this time, in order not to electrically form a closed loop, the conductive material 8 is not in contact with the overlapping portion. Finally, around the shield 7b for reducing the electric field, the bind tape 11 is wound several times around the shield 7b for reducing the electric field to fix the shield 7b for reducing the electric field.

  At that time, the insulating member 9b is arranged at intervals of 90 degrees starting from the flat portion where the laminated metal plates are laminated, and the flow path of the cooling medium is ensured as in the first embodiment. The insulating member 9b used here is a square member such as a general wooden pillar, and the side of the square member can be secured to a side height that does not contact the iron core when the shield 7b for relaxing the electric field is wound from FIG. Good. The length in the vertical direction only needs to be about the same as the length of the shield 7b for relaxing the wound electric field. In addition, the refrigerant flow path is secured to provide an iron core cooling effect. The insulating support member 9b may be inserted only for the purpose of supporting the shield for reducing the electric field when heat generation of the iron core is not a problem.

  Finally, there is a connection method between the shield 7b and the iron core for reducing the electric field, but since this is connected in the same manner as in the first embodiment, a detailed description is not described. If necessary, the shield for reducing the electric field of the present invention may be arranged not only on the side legs 3 but also around other iron core legs (inside the windings 4).

  When the shield 7b is arranged at the iron core junction corner portion 31b in this way, a member having a high dielectric constant is interposed between the high voltage winding 4 due to the shielding effect in the electric field, so that the electric field strength near the iron core corner portion 31b is weakened. . That is, as in the first embodiment, an effect is obtained in which a sharp corner is a curved surface having a large curvature radius.

  That is, if it is going to relieve the electric field of an iron core leg and an electricity application part with a prior art, the several resistor assembled to a metal plate and the shield which aims at electric field relaxation are needed separately. In addition, the attachment positions of these members are newly required in the equipment. This inevitably increases the size of the device. In the present invention, electric field relaxation and grounding can be realized at the same time with a single shield as described above, so the number of parts is minimized, and the number of parts is also small, so the installation space is also minimal, and the overall equipment is compact. Can also contribute to

1a, 1b, 1c, 1d Iron core yoke 2a, 2b, 2c Iron core leg 3 Side leg 4 Winding 5 Iron core fastening bracket 6 High-voltage lead wire 7a, 7b Shield 8a, 8b Conductive material 9a, 9b Insulating support member 10a, 10b Ground Wire 11 Binding tape 12 Clamping rod 14 Metal plates 16a and 16b String 19 Winding pressing member 20 Shield mounting hole 21 Insulating support member mounting holes 31a, 31b and 31c Corner 32 Insulating coating 33 Insulator a b Circular cross-sectional view

Claims (2)

  In an electromagnetic induction device iron core constructed by laminating a plurality of metal plates with an electrically insulating coating on the surface, a shield for reducing the electric field attached to the connecting corner between the electromagnetic induction device iron core leg and the iron core yoke The shield for reducing the electric field includes a bendable insulator, a conductor disposed inside or on one side of the insulator, and a ground wire electrically connected to the conductor, and the shield is the iron core. A shield for reducing the electric field of electromagnetic induction equipment, characterized by covering the corners with a smoothly curved shape and connecting both ends of the shield conductor and electromagnetic induction equipment core in the stacking direction with ground wires .   An electromagnetic induction device core configured by laminating a plurality of metal plates having an electrical insulating coating on a surface thereof, a shield for reducing an electric field attached to the electromagnetic induction device core leg, wherein the electric field relaxation is performed The shield is composed of a bendable insulator, a conductor disposed inside or on one side of the insulator, and a grounding wire electrically connected to the conductor, and the shield is smoothly smoothed along the core leg corners. A shield for reducing the electric field of an electromagnetic induction device, characterized in that it is covered with a curved shape, and both ends of the shield conductor and the electromagnetic induction device core are grounded by a ground wire.

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