JPH02146708A - Transformer - Google Patents

Abstract

PURPOSE:To obtain a transformer equipped with a magnetic shield which reduces not only leakage fluxes that are in a state of interlinkage with windings as well as eventual losses but also a mechanical capacity in the case of a short circuit by cooling filament or linear superconductors at a temperature below its critical temperature after winding the above superconductors in a concentric configuration with the windings at least at a place in inner and outer circumferences or inside of the windings so that these windings do not form a closed circuit. CONSTITUTION:Filament or linear superconductors 5 and 5' are wound into sizes larger than the axial directional sizes of windings 2 and 3 in a concentric configuration with the above windings at least at a place in inner and outer circumferences or inside of the windings so that these windings do not form a closed circuit and then these superconductors are cooled at a temperature below its critical temperature. For example, secondary and primary windings 2 and 3 are wound to an iron core 1 to form the mainframe of a transformer. Then superconductors 5 and 5' are wound at the outside of the primary winding 3 and between the secondary winding 2 and the iron core 1 in a concentric configuration so that these superconductors do not form a closed circuit and are wound into sizes larger than the axial directional sizes of the windings 2 and 3. The mainframe of the transformer is put into a cooling vessel 6 and the superconductors 5 and 5' are cooled at a temperature below its critical temperature by the use of a refrigerant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a transformer with improved magnetic shielding structure of the winding.

(Prior Art) Generally, a transformer has a secondary winding 2 wound concentrically around an iron core 1, and a primary winding 3 wound outside of the secondary winding 2 at a required insulation distance, as shown in Fig. 3. The configuration has the following. A transformer generates leakage magnetic flux during operation, but this leakage flux is distributed so that its energy is minimized. Therefore, near the axial center of the winding, magnetic flux has only an axial component and exists only near the air gap of the winding, but near the axial ends of the winding, it has a radial component and is present inside the winding. become widely distributed.

(Problem to be Solved by the Invention) When magnetic flux passes through the winding, eddy currents occur in each conductor of the winding, causing loss. Near the ends of the winding in the axial direction, the magnetic flux is widely distributed as shown by curve B in FIG. 4, and the amount of magnetic flux passing through the winding increases, causing a large loss. In addition, in the event of a short circuit, a large mechanical force is applied to the winding due to the electromagnetic force acting between the short circuit current and the leakage flux proportional to the short circuit current.
The windings and winding support structure are designed to withstand this mechanical force.
It was necessary to make it structurally strong by adding reinforcing materials, which led to an increase in the weight of the transformer.

The present invention reduces loss by changing the distribution of leakage magnetic flux and reducing leakage flux interlinking with the winding, and
An object of the present invention is to provide a transformer having a magnetic shield that reduces mechanical force during a short circuit.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, in the present invention, a wire is provided concentrically with the winding at at least one location on the inner periphery of the winding, the outer periphery of the winding, or inside the winding. It is characterized in that a strip or linear superconductor is wound so as not to form a closed circuit in the axial dimension of the winding, and the superconductor is cooled to below a critical temperature.

(Function) At temperatures below a critical temperature, a superconductor generates a magnetic pole with a polarity opposite to the magnetic flux near the superconductor due to the diamagnetic effect caused by the Meissner effect. As a result, it becomes difficult for magnetic flux to pass near the superconductor, and the number of magnetic fluxes near the superconductor decreases. Therefore, when a superconductor exists near a winding, the magnetic flux passing through the inside of the winding becomes smaller than when there is no superconductor.

(Example) FIG. 1 shows an example of the present invention. Iron core 1 - next winding 2.
The secondary winding 3 is wound to form a transformer body. This transformer body has a - outer side of the secondary winding 3.

The superconductor 5,5' is wound concentrically with the winding and with a dimension greater than the axial dimension of the winding so as not to form a closed circuit between the secondary winding 2 and the iron core 1. The transformer body is then placed in a cooling container 6, and the superconductor 5.5 is cooled to below the critical temperature by a cooling medium.

The superconductor 5.5' below the critical temperature generates a magnetic pole opposite to the nearby magnetic flux due to the Meissner effect.

Therefore, the magnetic flux becomes difficult to pass around the superconductor 5.5,
The magnetic flux will now avoid the superconductor.

Therefore, in the magnetic flux line diagram at this time, as shown in FIG. 1, the radial component is small even at the axial end of the winding, and most of the magnetic flux lines are oriented in the axial direction. Therefore, the magnetic flux distribution at the axial end of the winding becomes like curve A in Figure 4, and the amount of leakage magnetic flux interlinking with the winding can be made smaller than curve B in Figure 4 (conventional case). .

In this way, the leakage magnetic flux interlinking with the winding can be reduced, so
Since losses due to eddy currents can be reduced and the mechanical force acting on the windings during a short circuit can be reduced, the windings and the support structure for the windings can be simplified, and a transformer with one dimension of weight reduced can be provided.

Further, as shown in FIG. 2, the same effect can be obtained by winding the superconductor 5 between the primary and secondary windings 2 and 3. At this time, if the superconductor 5 is grounded, the superconductor 5 can also be used as a contact prevention plate.

[Effects of the Invention] As described above, the present invention can reduce eddy current loss caused by leakage magnetic flux by winding an electromotive conductor at at least one location on the inner periphery, outer periphery, and inside of the winding. Since the short-circuit mechanical force that sometimes occurs can be reduced, the winding and the winding support structure can be simplified, and the weight and size of the transformer can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing a transformer according to the present invention, FIG. 2 is a schematic sectional view showing another embodiment of the invention, FIG. 3 is a schematic sectional view of a transformer in a conventional configuration, and FIG. 2 is a distribution diagram showing the state of magnetic flux distribution at the axial end of the transformer. FIG. 1... Iron core, 2... Secondary winding, 3...-
Next winding. 5.5-...Superconductor. 6...Cooling container. Figure 3

Claims (1)

[Claims] A superconductor in the form of a strip or wire is wound concentrically with the winding at at least one location on the inner circumference, outer circumference, or inside the winding to a dimension greater than or equal to the axial dimension of the winding, and so as not to form a closed circuit. A transformer characterized by being cooled below temperature.