JPH064574Y2 - Air core reactor - Google Patents

Description

[Detailed Description of the Invention] [Technical field to which the invention belongs] The present invention mainly relates to the structure of an oil-filled air-core reactor provided with a magnetic shield made of an aluminum material.

[Prior art and its problems]

For high-voltage and large-capacity air-core reactors, the air-core coil is housed in a steel tank containing insulating oil to improve the withstand voltage performance and cooling performance of the air-core coil and to make it compact and lightweight. In this case, the tank made of steel with high magnetic permeability serves as a passage for the magnetic flux generated by the air-core coil, and in order to prevent heat generation and electrical loss of the tank from increasing, It is known that a magnetic shield made of a non-magnetic conductive material such as aluminum is formed between the side plate and the side plate so as to surround the air-core coil, and measures are taken to reduce the loss generated in the tank.

FIG. 3 is a schematic side sectional view of an essential part of an air-core reactor with a magnetic shield showing an example of a conventional technique, and FIG. 4 is an A- in FIG.
FIG. 3 is a cross-sectional view taken in the direction A, and auxiliary components such as a coil and magnetic shield tightening support structure, a bushing, a cooling device, and a conservator are omitted. In the figure, 1 is a tank made of steel having an insulating cooling medium 10 such as insulating oil contained therein, 2 is a cylindrical air-core coil immersed in the insulating oil 10, and 3 is an outer peripheral side of the air-core coil 2. It is a magnetic shield made of an aluminum plate arranged between the air-core coil 2 and the side plate 1A of the tank 1 so as to surround it. In the case of the drawing, the magnetic shield 3 is formed in a rectangular frame shape, and at least in the circumferential direction thereof. A gap portion 4 is formed to prevent a one-turn current path from being formed at one location. Further, reference numeral 100 is an isomagnetic line (hereinafter referred to as a magnetic flux line) showing a distribution of magnetic flux generated by an alternating current flowing through the air-core coil 2, and in the inner wall surface 3A portion of the magnetic shield 3 facing the air-core coil 2, the magnetic flux line is shown. Since a part of 100 interlinks with the inner wall surface 3A of the magnetic shield 3, eddy currents along the inner wall surface 3A flow to the surface layer portion of the magnetic shield close to the inner wall surface 3A,
A so-called magnetic shield effect that prevents the magnetic flux lines 100 from deeply penetrating into the magnetic shield 3 by the repulsive magnetic field generated by the eddy current is exhibited.

However, some of the leakage magnetic flux lines 101 reach the side plate 1A of the tank 1 through the upper and lower portions of the magnetic shield 3 where the magnetic shield 3 is not disposed, and the side plate 1 having a high magnetic permeability.
Since A serves as a magnetic path to form a closed loop of magnetic flux, iron loss occurs in the side plate 1A, and this iron loss causes a problem that the side plate 1A is locally heated. As a measure for reducing the leakage magnetic flux 101 entering and leaving the side plate 1A of the tank,
Known methods include increasing the vertical width of the magnetic shield, and increasing the distance between the air-core coil 2 and the magnetic shield 3 as much as possible by making the magnetic shield rectangular with respect to a cylindrical air-core coil. However, there are drawbacks that increase the weight of the magnetic shield, increase the size of the tank, and increase the amount of cooling medium. Further, if the gap 4 provided in the circumferential direction of the magnetic shield 3 is eliminated and a closed loop surrounding the air-core coil 2 is formed, a circulating current flows in the closed loop of the magnetic shield by the magnetic flux line 101, and the tank side plate 1A of the magnetic flux line 101. It is known in principle that it is possible to prevent wraparound to the side, but it is known that the reactance of the air-core coil decreases due to the circulating current, and the thickness of the magnetic shield corresponds to the circulating current. The fact is that it has not been put to practical use because of the drawbacks such as the need to increase

[Purpose of device]

The present invention has been made in view of the above circumstances, and provides an air-core reactor with a magnetic shield that can reduce leakage flux to the tank side without reducing reactance, and that can reduce loss, downsize, and reduce weight. With the goal.

[Key points of device]

The present invention provides a gap between a tank containing a cooling medium and a cylindrical air-core coil housed in the tank to prevent a short turn from surrounding the air-core coil with a predetermined distance. A magnetic shield cylinder made of an aluminum plate, a slit extending radially in a substantially disk shape having a peripheral edge portion coupled to one of the axial ends of the magnetic shield cylinder via an insulating material, and the cooling medium flow hole. Since it is configured to have a cylindrical magnetic shield with a bottom having a gap and a slit, a circulating current generated in the magnetic shield can be blocked, and an eddy current generated in the magnetic shield transmits the magnetic shield. This is to prevent the generation of magnetic flux leaking to the tank side.

[Example of device]

 The present invention will be described below based on embodiments.

1 is a schematic side sectional view of an essential part showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along line BB in FIG. In the figure, reference numeral 20 denotes a magnetic shield made of an aluminum plate formed in a cylindrical shape having a bottom and having a flow hole for the cooling medium 10. The magnetic shield is provided on the outer peripheral side of the cylindrical air-core coil 2 with a distance 6 required for insulation. A magnetic shield cylinder 21 arranged substantially coaxially with the coil 2 and a disc-shaped magnetic shield plate 22, and a support metal fitting 25 and a disc that are protruded inward from the lower end of the magnetic shield cylinder 21. The bottom end of the magnetic shield plate 22 is joined to the peripheral portion of the magnetic shield plate 22 with an insulating material such as an insulating washer 23 and an insulating bolt 24 to form a bottomed cylindrical magnetic shield 20. Further, since the magnetic shield cylinder 21 is provided with one gap 26 in the circumferential direction, the magnetic shield cylinder 21 is formed so as not to form one short-circuited turn, and the disk-shaped magnetic shield plate 22 is formed. Is provided with a slit 27 extending in the radial direction from the center thereof, and a circulating current circulating in the circumferential direction in the magnetic shield cylinder 21 by the gap portion 26 is provided in the slit 27.
By this, currents circulating in the magnetic shield plate in the circumferential direction are respectively blocked. Further, the magnetic shield cylinder 21 and the magnetic shield plate 22 are coupled to each other through an insulating material, so that a circulating current extending between them is blocked. The bottomed cylindrical magnetic shield 20 is connected and supported to a frame (not shown) that applies axial fastening force to the air-core coil 2 via an insulating material, and the magnetic shield cylinder 21 and the magnetic shield plate 22 are provided at one position each. It is held at ground potential by being electrically connected to the frame. Further, the circulation holes 28 and 29 for the cooling medium 10 are provided between the magnetic shield cylinder 21 and the peripheral edge portion of the magnetic shield plate 22 and in the essential portions of the magnetic shield plate, and the cooling medium 10 is passed through these circulation holes. Cooling is performed by convection or forced circulation on the surfaces of the air-core coil 2 and the magnetic shield 20.

In the air-core reactor configured as described above, the magnetic flux lines 10 generated by the alternating current flowing through the air-core coil 2
0 is the magnetic shield tube 21 so as to prevent the magnetic flux lines 100 from penetrating deep into the aluminum plate of the magnetic shield 20.
And the magnetic shield plate 22 penetrates the magnetic shield 20 by an eddy current generated along the inner wall surfaces of the tank 1 and the magnetic shield plate 22.
Since the leakage flux line 101 in FIG. 3 can be eliminated by the so-called magnetic shield effect in which the magnetic flux lines leaking to the side are blocked, the leakage flux lines interlinking with the tank 1 of the magnetic shield 20 formed in a bottomed cylindrical shape. Magnetic flux line 10 spread upwards
2 and only a few magnetic flux lines leaking from the holes of the cooling medium flow passages 28, 29, etc., and it is possible to significantly reduce or prevent the loss generated in the tank 1 and the local heating of the tank. In addition, the gap portion 26, the slit 27, the insulating material 2
Since the circulating current generated in the magnetic shield 20 is blocked by 3, 24, etc., it is not necessary to thicken the aluminum plate forming the magnetic shield, and the distance 6 between the air-core coil 2 and the magnetic shield cylinder can be increased. Since there is no need for magnetic flux leakage prevention measures that expand the vertical dimension of the magnetic shield cylinder, the magnetic shield can be made smaller and lighter, and the tank 1 is formed in a cylindrical shape to make the tank smaller, lighter, and a cooling medium. It is possible to reduce the amount of use of 10, and to reduce the size and weight of the entire air-core reactor. Furthermore, by blocking the circulating current generated in the magnetic shield 20, it is possible to prevent the reactance of the air-core reactor from decreasing, and therefore, there is a measure such as increasing the number of turns of the air-core coil to compensate for the decrease in quatcance. It becomes unnecessary, and the increase in weight of the air-core coil and the increase in man-hours can be prevented.

Although the magnetic shield plate 22 is arranged on the lower end side of the magnetic shield tube 21 in the above-described embodiment, the magnetic shield plate 22 may be arranged on the upper end side of the magnetic shield tube 21. Similar to the embodiment, it is possible to prevent leakage magnetic flux lines to the tank side.

[Effect of device]

As described above, the present invention provides a magnetic shield made of an aluminum plate arranged between a tank made of steel and a cylindrical air-core coil, in a radial direction with a magnetic shield tube having a gap for preventing circulating current. It was configured to have a bottomed cylinder shape having a cooling medium flow hole consisting of a slit-shaped shield plate having an elongated slit and a peripheral edge portion coupled to an axial end portion of a magnetic shield cylinder via an insulating material. . As a result, the magnetic flux lines generated in the air-core coil are prevented from penetrating deeply into the magnetic shield due to the eddy currents flowing in the magnetic shield tube and magnetic shield plate, respectively, and the leakage flux to the tank side, which was a problem in the conventional technology, is closed loop. By providing an air-core reactor with a magnetic shield, the amount of magnetic flux leaking through the tank wall can be significantly reduced, and thus the loss generated at the tank wall is low and the risk of localized heating of the tank is low. You can In addition, since the magnetic flux leakage is reduced by improving the structure of the magnetic shield, the vertical dimension of the magnetic shield tube eliminates the need for measures to reduce leakage magnetic flux lines, such as increasing the distance between the magnetic shield tube and the air-core coil, and the By eliminating the electric current, it is not necessary to take measures such as increasing the thickness of the aluminum plate that constitutes the magnetic shield and adding the number of turns of the air-core coil, so that it is possible to reduce the size and weight of the entire air-core reactor. Therefore, by combining these effects, it is possible to provide an air-core reactor which has low loss and excellent reliability, and which is small and lightweight and is excellent in economical efficiency.

[Brief description of drawings]

1 is a schematic side sectional view of an essential part showing an embodiment of the present invention, FIG. 2 is a sectional view taken along the line BB in FIG. 1, and FIG. 3 is a schematic side sectional view of a main part showing a conventional technique. 4 is a sectional view taken along the line AA in FIG. 1 ... Tank, 2 ... Air core coil, 3, 20 ... Magnetic shield, 6 ... Insulation distance, 10 ... Cooling medium, 21 ... Magnetic shield cylinder, 22 ... Magnetic shield plate, 23, 24 ... Insulating material, 2
5 ... Supporting hardware, 4, 26 ... Gap, 27 ... Slit, 2
8, 29 ... Flow holes, 100 ... Equal magnetic lines (magnetic flux lines), 10
1 ... Leakage magnetic flux line.

Claims (2)

[Scope of utility model registration request] 1. A tank comprising a steel material enclosing an insulating cooling medium, and a cylindrical air-core coil housed in the tank, wherein a predetermined distance is provided between the tank and the outer peripheral surface of the air-core coil. And a magnetic shield cylinder made of an aluminum plate having a gap for short circuit prevention at one circumferential position arranged coaxially with the air-core coil, and insulated at either end of the magnetic shield cylinder in the axial direction. A magnetic shield formed in the shape of a cylinder with a bottom and comprising an aluminum magnetic shield plate having a substantially disk-shaped slit extending in the radial direction and having a circulation hole for the cooling medium connected to each other via a material An air-core reactor characterized by that. 2. In the claim 1 of the utility model registration claim,
An air-core reactor characterized in that a circulation hole through which a cooling medium flows is formed between a magnetic shield cylinder and a peripheral portion of a magnetic shield plate.