JPS5821308A - Winding end insulating unit for gas insulated transformer - 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 The present invention relates to a winding end insulator for a gas insulated transformer.

Figure 1 shows a cross-sectional view of a general winding fixing structure of a gas insulated transformer, in which a low voltage winding 2 and a high voltage winding 3 are placed coaxially with an iron core 1 in a tank (not shown) filled with insulating gas. Between the low-voltage winding 2 and the high-voltage winding #3, linear spacers 5 are inserted at multiple locations around the insulating cylinder 4 and around the entire circumference in order to maintain insulation and form a cooling duct. On the other hand, a shield ring, a so-called clamp ring 6, is installed at the end of the winding and wire to alleviate the electric field.
Further, an insulating support column 8 is arranged on the axially outer side of the clamp ring 6 in order to support the winding and the clamp ring 6 and to maintain an insulation distance between the clamp ring 6 and the winding support fitting 7. are placed at several locations around the circumference.

In the above structure, for example, at the lower end portion of the high voltage winding 3 surrounded by the broken line frame A in FIG. 1, as shown in detail in FIG. In the section, a wedge-shaped gas gap a is formed between the linear spacer 5 and the linear spacer 5.
Further, a wedge-shaped gas gap c is formed between the insulating support pillar 8 and the insulating support pillar 8, respectively. However, the linear spacer 5 and the insulating support column 8 are generally made of insulating paper or plastic insulating material, but these solid insulating materials have a dielectric constant of about 3 compared to the insulating gas sealed in the transformer. It will be more than twice as large. Therefore, a wedge-shaped gas gap at be C
The gap between the equipotential lines becomes very narrow in this region. That is, these wedge-shaped gas gap areas have a higher electric field than other clamp ring surface areas.

As mentioned above, the dielectric strength of the insulating gas sealed in the transformer is lower than that of solid insulating materials, so dielectric breakdown generally occurs due to
It starts from the insulation part. Therefore, wedge-shaped gas gaps a, b, and c are formed on the surface of the clamp ring 6 to form high electric field areas.
Partial discharge is likely to occur from this area, and this partial discharge is
There is a risk that the damage will develop along the surfaces of the insulating cylinder 4 and the insulating support column 8 in the winding axial direction, and eventually lead to dielectric breakdown between the clamp ring 6 and the winding support fitting 7. For this reason, in the past, the main insulation distance between the high voltage winding 3 and the low voltage winding 2 and the clamp ring 6 were The end insulation distance between the winding support fitting 7 and the winding support fitting 7 was determined.

However, in order to reduce the size of transformers in the future, it will be essential to shorten these insulation dimensions, which are the main factors determining the size of transformers.

The present invention has been made in view of the above situation, and provides a winding end insulating device for a gas insulated transformer that can shorten the insulation dimension of the winding end without reducing the dielectric strength of the winding end. It is intended to.

The winding end insulating device for a gas insulated transformer of the present invention comprises a winding and an insulating cylinder arranged around the outer periphery of an iron core with a plurality of linear spacers interposed in a tank filled with insulating gas, and A shield ring disposed at the axial end, a plurality of insulating support columns arranged circumferentially outside the shield ring in the axial direction, and the winding, the shield ring, the insulating support columns, etc. arranged in the axial direction. A winding support bracket is provided to integrally support and fix the winding, and the insulating support column has a groove formed in the radial direction on the end face opposite to the high voltage winding, and the connecting rod fitted in the groove respectively. an inner ring electrode that is fixed and disposed at a position in contact with the inner and outer peripheries of the insulating support column so as to be flush with the end surface of the insulating support punch, and whose inner periphery side protrudes from the inner periphery of the high voltage winding; and an outer periphery of the high voltage winding. An outer ring electrode with an outer circumferential side protruding further outward, and an insulating ring sandwiched between the high-voltage winding and the insulating support pillar and disposed so as to be in contact with the outer periphery of the insulating cylinder and in contact with the end face of the linear spacer. It is.

Hereinafter, an example of the winding end insulating device for a gas insulated transformer according to the present invention will be described with reference to FIGS. 3 to 5, with the same parts as those in the prior art designated by the same reference numerals and explanations of the same parts omitted. 3 is a detailed view of the same portion as A in FIG. 1, FIG. 4 is a cross-sectional view of the shield ring in FIG. 3, and FIG. 5 is a perspective view of the insulating support column in FIG. 3. 11 is a shield ring, shield ring 1
1 is an inner ring electrode 12, an outer link electrode 13 disposed outside the inner ring electrode 12, and an inner and outer ring electrode 12.
．． It consists of a plurality of connecting rods 14 that connect between the connecting rods 13. The insulating support column 15 is provided with a radial groove 16 at a depth into which the connecting rod 14 is inserted. shield link 1
The inner ring electrode 12 and the outer ring electrode 13 of No. 1 are disposed in contact with the inner and outer peripheries of the insulating support column 15 and on the same plane as the end surface of the insulating support column 15, respectively. It is attached so as to contact the sandwiched disc-shaped insulating ring 9. Further, the insulating ring 9 is in contact with the outer periphery of the insulating rtJ4 and is also in contact with the end surface of the linear spacer 5. In addition, the inner and outer ring electrodes 12.13
A gap is provided in a part of the circumferential direction of the shield ring 11 to prevent eddy current from flowing in the inner circumferential direction of the ring, thereby suppressing stray load loss within the shield ring 11.

In the above insulation structure, a linear spacer 5 is provided on the surface of the shield link 11 arranged at the end of the winding as in the conventional case.
The high electric field gas wedge caused by the insulating support pillar 8 is not formed, and the maximum electric field on its surface (the electric field applied to point d) is reduced compared to the value of a conventional gas wedge. This means that if the winding end insulation distance and the main insulation distance are the same as conventional ones, and the curvature of the inner and outer ring electrodes 12.13 is 10++ m, the maximum electric field at point d will be the same as the gas wedges a, b of the conventional structure. It is clear from the electric field analysis results that the electric field at point c can be reduced by about 0%. In addition, since the ring electrodes 12 and 13 are arranged to protrude from the inner and outer surfaces of the high voltage winding 3, as shown in FIG. It is possible to reduce the degree of intrusion between the wire and the spectacular winding wire 3. The electric field generated by the insulating ring 9 in the gas wedge e at the inner corner of the high voltage winding 3 and the gas wedge f at the outer corner of the end of the high voltage winding 3 is prevented from becoming higher than the conventional value at the same portion. can.

Therefore, at the end of the winding, the voltage generated by partial discharge from the shield link 11 can be increased compared to the conventional method without causing a decrease in the dielectric strength of the winding, and the dielectric strength of the end of the winding can be increased. You can improve. Therefore, the dimensions of the end insulation distance and the main insulation distance at the ends of the winding can be reduced compared to the conventional case. In this case, the latter needs to be dimensioned to satisfy the condition that no dielectric breakdown occurs from the winding side, and it is necessary to achieve insulation coordination between the main insulation part and the end of the winding.

In this way, the winding end insulating device of the gas insulated transformer of this embodiment can prevent the winding ends from decreasing, which is the main factor determining the size of the transformer, without reducing the dielectric strength of the winding ends. Since the end insulation distance and the main insulation distance can be reduced, the transformer can be made smaller and lighter.

As described above, the winding end insulating device for a gas insulated transformer of the present invention has the effect of reducing the end insulation distance and main insulation distance at the ends of the winding, thereby making the transformer smaller and lighter. be.

[Brief explanation of the drawing]

Figure 1 shows a conventional gas insulated transformer. 2 is a detailed view of part A in FIG. 1, and FIG. 3 is a second embodiment of the winding end insulating device for a gas insulated transformer according to the present invention.
4 is a cross-sectional view of the shield ring of FIG. 3, and FIG. 5 is a perspective view of the insulating support column of FIG. 3. 1... Iron core, 2... Low voltage winding, 3... High voltage winding,
4... Insulating tube, 5... Linear spacer, 7... Winding support fitting, 9... Insulating ring, 11... Shield ring, 12... Inner ring electrode, 13... Outer side Ring electrode, 14...Liquid cylinder 10 Sake 2 diagram

Claims (1)

[Claims] 1. A winding and an insulating cylinder arranged around the outer periphery of an iron core with a plurality of linear spacers interposed in a tank filled with an insulating gas;
a shield ring disposed at the axial end of the winding;
A plurality of insulating support columns arranged circumferentially on the axially external side of the shield ring, and a winding support fitting for integrally supporting and fixing the winding, the shield ring, the insulating support columns, etc. in the axial direction. The insulating support column has a groove formed in the radial direction on the end face facing the high voltage winding, and the insulating support column is fixed to the connecting rod fitted in the groove and is in contact with the inner and outer periphery of the insulating support column. an inner ring electrode arranged flush with the end surface of the insulating support punch and having an inner circumferential side protruding from the inner circumferential surface of the high voltage winding; and an outer ring electrode having an i circumferential side protruding from the outer circumferential surface of the high voltage winding; A winding end of a gas insulated transformer, comprising: a high voltage winding; and an insulating ring sandwiched between the insulating support pillars and disposed in contact with the outer periphery of the insulating tube and in contact with the end face of the linear spacer. Part insulation device.