JPS6182410A - Magnetic shielding device of stationary induction electric apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a magnetic deflection device used for the purpose of reducing leakage magnetic flux in a static Itlif device such as a transformer or a reactor.

[Technical background of the invention and its problems] In recent years, as static M conductors such as transformers have become larger in capacity and made smaller and lighter to meet transportation conditions, the amount of magnetic flux leaking from the windings has also increased. There is a tendency.

Therefore, iron core fastening metal fittings, which are components of stationary induction electric appliances,
Leakage magnetic flux intrudes into metal structures such as winding clamps and tanks, and the resulting increase in stray loss and local overheating are viewed as problems from various viewpoints, including the performance and durability of stationary induction appliances. It's starting to look like this.

As a measure to eliminate and reduce the negative effects of such leakage magnetic flux, conventional magnetic shields in the form of annular discs made of silicon steel strips wound around the upper and lower ends of the windings have been installed. ,
A magnetic blocking device is used that actively absorbs leakage magnetic flux from the windings using this magnetic shield to suppress the leakage magnetic flux from entering other structural members such as core clamping plates.

The second factor is a vertical front view of a conventional inner iron type transformer equipped with a magnetic deflection device.
and an outer winding 4 are wound concentrically. As shown in FIG. 3, a silicon steel strip is wound between the upper and lower ends of the inner winding 3 and the outer winding 4 and the core fastening fittings 2 disposed above and below them to form an annular disk shape. Magnetic shield 5 formed in
Attach. This magnetic shield 5 also serves as a view of the winding clamping plate, and actively absorbs the leakage magnetic flux 7 from the windings 3.4 and returns it to the iron core 1, reducing the amount leaking into the tank wall 6. It also prevents leakage magnetic flux from entering metal structures such as the iron core clamp 2, reducing stray loss and preventing local heating.

As described above, by providing the magnetic shields 5 at the upper and lower ends of the windings 3 and 4, leakage magnetic flux is suppressed, localized overheating of the inner structural material due to leakage magnetic flux is prevented, and stray loss is reduced. However, on the other hand, the eddy current loss of the magnetic shield 5 itself due to leakage magnetic flux is not sufficiently reduced.

That is, in the conventional magnetic shield 5 shown in FIGS. 2 and 3, a thin ferromagnetic material such as a silicon steel strip is wound in an annular shape, an adhesive is interposed between the wound layers, and then heated. By curing, the entire magnetic shield is integrally molded, and notches 5a are provided in the radial direction so as not to form one electrical turn.

The silicon steel strip is a thin plate with a thickness of less than 1 mm, and an electrically insulating layer several μm thick is applied to its surface.

Therefore, in theory, each layer of the silicon steel strip is electrically insulated, and even if magnetic flux leaks from the windings and enters the magnetic shield 5, no large eddy current will flow. However, normally, a force error of about 20 μm is generated at the edge of a silicon steel strip when cutting a silicon steel material into a plate of a desired width. Therefore, by winding the silicon steel strip, a force greater than the thickness of the insulating layer will come into contact between the layers at the edges, creating electrical continuity, and the magnetic shield will become as if it were a large, wide metal plate. . As a result, a large eddy current was generated in the magnetic shield 5 due to the invading leakage magnetic flux, and the purpose of the magnetic shield, which was to prevent local overheating and stray loss, could not be sufficiently prevented. In addition, even if the force edges at the edges of the silicon steel strip are removed using a file or a grindstone, the metal parts are still exposed, so if the silicon steel strip is tightly wound, the edges will be extremely conductive. , electrical insulation between layers was difficult, and large eddy currents were likely to flow in the magnetic shield.

[Purpose of the Invention] The present invention provides a magnetic shielding device for stationary induction appliances that eliminates the above drawbacks and suppresses eddy current loss generated in the magnetic shield, reduces stray loss, and prevents local overheating. The purpose is to obtain.

[Summary of the Invention] In order to achieve the above-mentioned objects, the present invention has been made by superimposing and winding a ferromagnetic material constituting a magnetic shield with a polymer non-woven fabric, and impregnating the polymer non-woven fabric with an adhesive to create a ferromagnetic material. By integrating the body, an insulating layer made of non-woven polymer fabric prevents contact conduction of force edges at the edges of the ferromagnetic material, thereby preventing large eddy currents from flowing in the magnetic shield. This is a characteristic feature.

[Embodiments of the invention] An embodiment of the present invention shown in the drawings will be described below.

In FIG. 1, the magnetic shield 5 of the present invention has a plate width of 20 mm.
A ferromagnetic material 8 having a high magnetic permeability with a thickness of 1# or less, for example, a non-oriented silicon steel strip or a grain-oriented silicon steel strip, having a thickness of approximately the same width as the ferromagnetic material 8 is used. and thickness 0
．． 02 trtm to about 0.1 trtm, and is wound to form an annular disk shape of a predetermined size while overlapping the insulating material 9. Generally, when mechanical stress is applied to a silicon steel strip, the magnetic properties deteriorate and the hysteresis loss generated in the material increases, so a material that is wound in a roughly C-shaped circle and annealed is used. In addition, the insulating material to be overlapped with the ferromagnetic material 8 is made of a polymer, so that it can be well impregnated with the adhesive. !
! As the cloth 1, for example, a polyester nonwoven fabric or a polyimide nonwoven fabric with excellent heat resistance is used. The adhesive, such as an epoxy adhesive, is impregnated into the nonwoven fabric under atmospheric pressure or vacuum, so it has extremely good impregnating properties, and the nonwoven fabric and the ferromagnetic material 8 are sufficiently bonded. The magnetic shield 5 is provided with a slit at one location in the radial direction as in FIG. 3 to prevent one electrical turn.

The magnetic shield 5 constructed in this way has an insulating material made of nonwoven fabric inserted between the layers of the ferromagnetic material 8, and because the insulating layer is thick, the ferromagnetic materials 8 come into contact with each other at their edges due to force. However, electrical interlayer insulation can be ensured without conduction. Therefore, even if leakage magnetic flux enters the flat portion of the magnetic shield 5, a large eddy current will not flow through the magnetic shield 5, and local overheating will not occur. In addition, since nonwoven fabric is used as an insulator, the adhesion between the ferromagnetic material 8 and the nonwoven fabric is much better than the adhesion between ferromagnetic materials, and a very strong magnetic shield that is not easily damaged by mechanical balance can be obtained. It will be done.

[Effects of the Invention] As described above, according to the present invention, the ferromagnetic material constituting the magnetic shield is wrapped in a superimposed manner with a polymeric nonwoven fabric, and the ferromagnetic material is integrated by impregnating the polymeric nonwoven fabric with an adhesive. As a result, it is possible to obtain a magnetic shielding device for a stationary induction appliance that suppresses eddy current loss generated in the magnetic shield, reduces stray loss, and prevents local overheating.

[Brief explanation of drawings]

Fig. 1 is a perspective view of the main part of a magnetic shield showing an embodiment of the present invention, Fig. 2 is a longitudinal sectional front view showing a core type transformer equipped with a conventional magnetic shielding device, and Fig. 3 is the same plane. It is a diagram. DESCRIPTION OF SYMBOLS 1... Iron core, 2... Iron core tightening fitting, 3, 4... Winding wire, 5... Magnetic shield, 5a... Slit, 6...
...Tank, 7...Leakage magnetic flux, 8...Ferromagnetic material, 9
...Nonwoven fabric.

Claims (1)

[Claims] A magnetic shield for electrostatic induction appliances in which an annular disc-shaped magnetic shield is installed between the winding wound around the core leg and the clamping fittings installed at the upper and lower ends of the winding. The apparatus is characterized in that a ferromagnetic material having high magnetic permeability is layered and wound around a polymer nonwoven fabric, and the polymeric nonwoven fabric is impregnated with an adhesive to integrate the ferromagnetic material to form a magnetic shield. Magnetic shielding device for stationary induction electric appliances.