JPS5988810A - Coil edge insulation structure of gas insulated transformer - Google Patents

Abstract

PURPOSE:To make short the dimention of insulator at the coil edge without lowering insulation strength by covering a shield ring with an insulating layer through an insulating ring having the prescribed shape. CONSTITUTION:An insulating ring 7, which is formed in such a manner that the section in the axial direction is protruded, the protruded surface is placed in contact with the flat surface in the axial direction of the shield ring 2 and the ring 2 is located within the range of the axial direction width, is arranged. An insulating layer 8 is provided in such a way as covering the ring 2 through the insulating ring 7. Thereby, a partial discharge generating voltage at the shield ring 2 becomes high and development of partial discharge can be suppressed. Dimension of insulator at the coil edge can be reduced without lowering insulation strength.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an improvement in the winding end insulation structure of a gas insulated transformer.

[Prior art]

FIG. 1 shows a sectional view of a main part of a conventional winding end insulation structure in a gas insulated transformer. A high-voltage winding 1 is wound coaxially with an iron core (not shown), and a shield link 2 for mitigating the electric field is arranged on the end surface of the high-voltage winding 1. In order to support the wire 1 and the shield ring 2 and maintain an insulation distance between them and the winding support fitting 3, a prismatic insulating spacer, that is, an insulating stand 4 is provided.
are placed in several places around the circumference. On the other hand, although not shown, there is a gap between the high-voltage winding 1 and the low-voltage winding, which is wound coaxially with the iron core inside the high-voltage winding 1, in order to maintain an insulating distance and form a cooling duct. As an insulating spacer, a cylindrical insulating tube 5 and square rod-shaped @ line duct pieces 6 are inserted at several places around the entire circumference.

In such a winding end insulation structure, there is a wedge-shaped gas gap a, b between the corner of the shield link 2 and the insulating frame 4, and a wedge-shaped gas gap a, b between the corner of the shield link 2 and the straight duct piece 6. Gas gaps c and d are formed, respectively. However, the dielectric constant of the insulating material used for the insulating spacer is 3 to 5 times higher than that of the insulating gas sealed in the tank. Therefore, in the wedge-shaped gas gaps a and d, the distance between the equipotential lines is extremely narrow. 1, that is, these portions have a commercial electric field compared to the gas gap at the three corners of the shield ring that do not face the insulating spacer. However, the dielectric strength of the insulating spacer itself is generally higher than that of insulating gas.

Therefore, in the shield link 2, partial discharge is likely to occur from the wedge-shaped gas gaps a and d, and this partial discharge is caused by winding along the surfaces of the insulating spacers such as the straight duct piece 6, the insulating frame 4, and the insulating tube 5. There is a possibility that the damage will progress in the wire axis direction and eventually lead to dielectric breakdown between the shield link 2 and the winding support fitting 3.

In this case, the insulation distance between the shield link 2 and the winding support fitting 3, so-called end insulation dimension, and the insulation distance between the high-voltage winding l and the low-voltage winding coaxially wound with it, so-called The larger the main insulation dimension is, the more the electric field strength in the wide gas gaps a and d can be completely reduced, and the creeping electric field strength of the insulation spacer also becomes lower, so the partial broadcast generation voltage increases by more. Moreover, since the progress of partial discharge is also suppressed, the dielectric strength of the winding ends is improved. However, increasing the end insulation dimensions and the main insulation dimensions is undesirable because it increases the dimensions of the transformer itself, which increases the size of the transformer.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a winding end insulation structure for a gas insulated transformer that can reduce the insulation dimension by increasing the voltage at which partial discharge occurs in the shield ring and suppressing the progress of partial discharge. .

[Summary of the invention]

The present invention provides a winding end insulation structure for a gas insulated transformer, which has a fully convex axial cross section, the protruding surface of which is in contact with a radially flat surface of a shield ring disposed at the winding end, Further, the present invention is characterized by providing an insulating link configured such that the shield ring is located within the range of the radial width, and an insulating material layer that completely covers the insulating ring and/or the lead link.

[Embodiments of the invention]

Embodiments of the present invention will be explained with reference to FIGS. 2 to 4.

In FIG. 2, 7 has a convex axial cross section, and its protruding surface is in contact with the radially flat surface of the shield link 2, and the shield link 2 is positioned within the range of its radial width. The constructed insulating ring 8 is connected to the insulating ring 7 through the insulating ring 7.
An insulating layer covering the shield ring 2, for example, an insulating layer formed by winding an insulating tape, or a U
It is constructed by stacking two shaped insulating barriers facing each other and wrapping the outer periphery with insulating tape. Note that the radial inner end surface of the insulating ring 7 is adjacent to the insulating tube 5 with the insulating layer 8 interposed therebetween, so that the radial position of the insulating link 7 is fixed. Further, the shield link 2 is bonded to the insulating ring 7 with an adhesive to fix its radial position.

In such a winding end insulation structure, all the corners of the seal re-dag 2 face the gas gap 9, so that there is no possibility of forming a wedge-shaped gas gap that causes electric field concentration as in the conventional case. In addition, an insulating ring 7 is attached to the radially flat surface of the shield link 2.
Since the protruding surfaces of the insulating ring 7 are in contact with the shield link 2, the axial creepage of the insulating ring 7 is formed in this part, but since the creeping direction is almost the same as the direction of the electric field, the electric field of the gas gap in this part is The concentration is smaller than in a conventional wedge-shaped gas gap. For this reason, the electric field strength of the gas gap on the surface of the shield link 3 can be reduced to a wedge-shaped gas %I/
Since it can be lowered compared to C, Shield Link 2
The voltage at which partial discharge occurs is higher than before. Even if a partial discharge occurs, the insulating layer 8 is provided so as to cover the shield ring 2. Therefore, the partial discharge will be contained within the insulating layer 8, and will not be exposed to the outside. teeth,
Progress is not easy. Therefore, shield link 2
The dielectric breakdown voltage from to the winding support fitting 3 can be lowered compared to the conventional case.

FIG. 3 shows a complete alternative embodiment. The difference from FIG. 2 is that the insulating ring 7' is disposed on the side of the winding 1 and is shaped like a flat plate without any protrusions.

In this case, a wedge-shaped gas gap e is formed between the corner of the shield link 2 facing the high-voltage coil 2 and the insulating ring 7'.
, f are formed, but since the potential difference between the opposing high voltage winding ffMl and the shield link 3 is small, the insulating link 7
If the thickness of ′ is set to an appropriate value, a wedge-shaped gas gap [
The 'Ii field strength of e and f can be lowered. Therefore, this embodiment has the same effects as those in FIG. 2, but since the cross section in the axial direction has a convex shape, the number of insulating rings 7 that are time-consuming to manufacture is limited. This can be halved compared to the case shown in Figure 2.

FIG. 4 shows still another embodiment in which the water is divided. The difference from FIG. 2 is that a groove is provided in the radially flat surface portion. The protrusion of f [
Insert shield ring 2' and insulation ring 7.
This is the point where all the parts are joined. In this configuration, a wedge-shaped gas gap that becomes an electric field is not formed, so it has the same effect as the embodiment shown in FIG. Since the position can be adjusted, the positional relationship between the two can be maintained completely.

〔Effect of the invention〕

According to the present invention, it is possible to measure the partial discharge inception voltage at the shield ring arranged at the end of the winding of a gas insulated transformer, and furthermore, it is possible to suppress the progress of partial discharge, so that the dielectric strength The insulation dimension at the end of the winding can be shortened without reducing the winding.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a main part of a winding end insulation structure of a conventional gas-insulated R transformer, and Fig. 2 is a cross-sectional view of an embodiment of the winding end insulation structure of a gas-insulated transformer according to the present invention. 3, &' and 4 are a sectional view of FIG. 2 and a cylindrical portion of another embodiment of the present invention. 1...5, masterpiece wire, 2.2'...shield ring,
3... Winding support metal fitting, 7, 7'... Insulation ring, 8
...Insulation Figure 1 Figure 2 Figure 49 Figure 3 tJ-Figure

Claims (1)

[Claims] 1. A winding wound around an iron core in a tank filled with insulating gas, a shield ring placed at both ends of this winding, and supporting the winding and shield ring from the axial and radial directions. In a device consisting of a plurality of insulating spacers to be fixed, the cross section in the axial direction has a fully convex shape, and the protruding surface is
The entire insulating layer is connected to the shield ring through an insulating ring that is arranged so that the shield ring is in contact with the radially flat surface of the shield ring and that the shield ring is located within the range of the radial width. Features a gas transformer winding end insulation structure.