JPH0746662B2 - Oil-filled static induction - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static induction electric generator such as a transformer or a reactor which is insulated by a composite insulator of a solid insulator and insulating oil, and has a reduced insulation dimension. The present invention relates to an oil-filled static induction electric machine having an insulating structure suitable for reducing the number of oil-fired electric machines.

[Background of the Invention]

The insulation configuration of an oil-filled static induction generator, such as a power transformer,
It is usually composed of composite insulation of insulating paper and insulating oil. The relative permittivity of the insulating paper is higher than the relative permittivity of the insulating oil, and therefore, the electric field distribution in this composite insulating structure is high in the insulating oil inside where the relative permittivity is low. Therefore, unless the insulating oil quality or the insulating paper is higher than that, dielectric breakdown occurs from the oil gap portion having low dielectric strength. Therefore, the insulation design of a transformer usually determines a predetermined oil gap width so as to increase the insulation strength of the insulation oil gap, and the insulation width dimension is determined by this. It was difficult to achieve the reduction of electric appliances.

As a configuration to overcome this, Hitachi Review VoL.65, No.5 (198
3-5) "3. 3 hybrid insulation" in "Technical Trends of Power Transformers" on pages 5 to 10 is mentioned. In this hybrid insulation, the data of each part of the induction electric device is cross-organized and integrated, and the oil gap subdivision method that divides the oil gap by the insulating paper layer and the filling insulation method that fills the oil gap with the dielectric are combined. , The rationalization of the structure by the best allocation of both. However, there is a limit to the reduction of the hybrid insulation dimension, and the insulation dimension is further reduced.
It was difficult to reduce the size of the static induction machine itself.

[Object of the Invention]

An object of the present invention is to provide an oil-filled static induction electric device which can reasonably reduce the insulation dimension of a composite insulation structure composed of a solid insulation material and insulation oil, except for the above-mentioned drawbacks of the prior art. It is in.

[Outline of Invention]

In order to achieve this object, the present invention, in a composite insulation structure composed of a solid insulator and insulating oil, the solid insulating material near the line side terminal is substantially equal to the specific induction rate of the insulating oil, It is characterized by being composed of an insulator having a relative permittivity lower than that.

Example of Invention

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows an embodiment in which the present invention is applied to a typical two-winding transformer in which terminals are drawn from both upper and lower ends. Main insulation is arranged between the low voltage winding 2 and the high voltage winding 3 wound around the magnetic core 1.

This main insulation consists of three layers of solid insulators 4a, 4 in the illustrated embodiment.
b and 4c, and oil gaps 5a to 5d formed between these solid insulators and between the solid insulators and each winding. 2a, 2b
Is a terminal of the low voltage winding 2, 2a of which is a line side terminal, 3a and 3b are terminals of a high voltage winding 3, and 3a of which is a line side terminal. 6a, 6
b and 7a, 7b are shield rings arranged at the upper and lower ends of the low voltage winding, respectively. Solid L-shaped insulators 8 and 9 are arranged between the low voltage winding 2 and the magnetic core 1 and between the high voltage winding 3 and the magnetic core 1, respectively.

The voltage distribution in the winding height direction of the low voltage winding 2 and the high voltage winding 3 is distributed as shown in FIG.

That E ₁ a maximum voltage of the voltage distribution Eh In line terminal 3a side of the high voltage winding 3, when the highest pressure of the voltage distribution E _l The line terminal 2a side of the low-voltage winding 2 and the E _2, the main insulating section, The portion having the largest voltage sharing is the portion sharing the voltage difference E ₃ between the voltages E ₁ and E ₂ , that is, the vicinity of the upper portion of the winding where the line terminals 2a and 3a are drawn.

In general, in a winding gap in which different voltages are induced, the shared voltage for each component is determined in inverse proportion to the relative permittivity of the insulating material. In other words, in a portion composed of a plurality of insulating materials having different relative permittivities, the lower the relative permittivity, the greater the shared voltage. Therefore, the required insulation dimension is determined by the dielectric strength of the low relative dielectric constant material.

When the main insulation structure of FIG. 1 is modeled as shown in FIG. 3, the thickness of each solid insulator 4a to 4c is l ₁ , their relative permittivity is ε ₁ , the insulating oil gap 5a to The thickness of 5d is l ₂ , their relative permittivity is ε ₂ , the thickness of the main insulation, that is, the width dimension between the high and low voltage windings is l ₀ , the total thickness of the solid insulator 4 is l ₁₀ , the oil gap Let l _{20 be} the total thickness of 5 and V be the differential voltage applied to the main insulating part. L ₀ = l ₁₀ + l ₂₀ (1) The shared voltage of the solid insulator 4 is V ₁ and the insulating oil gap 5 if the divided voltage and V _2, where _{V = V 1 + V 2 ......} (2), since the shared voltage of the insulating component as described above is determined in inverse proportion to dielectric constant, From equation (3) As is clear from this equation (4), by setting ε ₁ ≦ ε _2, that is, by making the relative permittivity of the solid insulator 4 approximately equal to or smaller than the relative permittivity of the insulating oil gap 5. Can be

Normally, the main insulation dimension of the transformer is the one in the part where the shared voltage is maximum. The required insulation dimension is determined by the value of. Low dielectric constant of the solid insulator top 4a ₁ ~4c ₁ part of the solid insulator 4a~4c of sites located windings top of at least the line terminal side in accordance connexion present embodiment, for example, methylpentene, tetra An insulating material obtained by mixing polymer fibers such as fluoroethylene and pulp fibers at an appropriate density is used.

Of course, the solid insulator 4 as a whole may be the mixed insulating material.

Usually, the dielectric constant of the insulating oil is 2.2 to 2.3, and the dielectric constant of the pressboard constituting the insulator is 3.5 to 4.5, but the polymer fibers such as methylpentene and tetrafluoroethylene and pulp fibers The relative permittivity of the insulating material mixed with and can be set to about 2.

Therefore, according to the present embodiment, since the shared voltage in the main insulation can be distributed more to the solid insulator side, which has a higher dielectric strength than the insulating oil, it is possible to reduce the thickness of the solid insulator. The thickness, that is, the width dimension of the main insulator can be reduced by this amount, and the transformer can be downsized.

FIG. 4 shows an embodiment in which the present invention is applied to an upper and lower parallel winding structure in which the line side terminal 3a of the high voltage winding 3 is drawn out from the central portion of the winding 3.

In the winding configuration of FIG. 4, as shown in FIG. 5, the voltage sharing in the winding height direction is such that at least the maximum difference voltage E ₄ in the main insulation is located in the central portion, so In this case, the solid insulators 4a to 4c in the vicinity of the parts are arranged with an insulator having a low specific electric conductivity, which is a mixture of the above-mentioned polymer fibers and pulp fibers.

In the above embodiments, the case where the present invention is applied to the main insulating portion of the transformer is illustrated, but the same effect can be obtained even when applied to the L-shaped insulator interposed between the end of the winding and the iron core. However, detailed description thereof will be omitted.

In addition, reactors that are oil-filled induction devices other than transformers, P
Needless to say, the present invention can be applied to insulation of T, PCT and the like.

〔The invention's effect〕

As described above in detail with reference to the embodiments, according to the present invention, in the composite insulation structure of the solid insulator and the oil gap,
Since it is possible to increase the sharing voltage in the solid insulator portion having high insulation strength and reduce the insulation size, it is possible to provide an oil-filled static induction electric device in which the size of the electric device can be reduced.

[Brief description of drawings]

1 and 4 are longitudinal sectional views of a transformer winding and its insulation structure according to the present invention, FIG. 3 is a modeled view of a main insulating portion, and FIGS. 2 and 5 are respectively FIG. FIG. 5 is a diagram showing a voltage distribution in the height direction of the transformer winding of FIG. 4. 1: Magnetic iron core, 2: Low voltage winding, 3: High voltage winding, 4: Solid insulator,
5 :: insulating oil gap

Claims (3)

[Claims] 1. A magnetic iron core, and at least one winding wound around the magnetic iron core, and electrically between the windings or between the winding and the magnetic iron core by a solid insulator and insulating oil. The static induction inductor insulated according to claim 1, wherein the vicinity of the line side terminal of the solid insulator is made of an insulator having a relative permittivity lower than that of the insulating oil. 2. The oil fill according to claim 1, wherein the vicinity of the line-side terminal is a portion drawn out from at least upper portions of the low-voltage winding and the high-voltage winding in a winding height direction. Stationary induction device. 3. The oil-filled static induction machine according to claim 1, wherein the vicinity of the line-side terminal is at least a portion drawn out from a central portion in the winding direction of the high-voltage side winding.