CN100407345C

CN100407345C - External insulation structure of power transformer

Info

Publication number: CN100407345C
Application number: CN2005101307840A
Authority: CN
Inventors: 张国强; 郭卉; 顾国彪
Original assignee: Institute of Electrical Engineering of CAS
Current assignee: Institute of Electrical Engineering of CAS
Priority date: 2005-12-30
Filing date: 2005-12-30
Publication date: 2008-07-30
Anticipated expiration: 2025-12-30
Also published as: CN1794383A

Abstract

The present invention relates to an external insulation structure of a power transformer. When the external insulation of the power transformer is the air, in order to increase a creepage distance of the peripheral surface in the air insulation from all leading-out wire positions of the head ends, the neutral points, divided lead wires of a high pressure, a medium pressure and a low pressure to other electric potential positions, a transformer lead wire is directly provided with a porcelain sleeve [50] composed of a big umbrella skirt [30] and a small umbrella skirt [40] in the position firmly close to a lead wire [10] outside of the cylinder wall, the tube wall or the side wall [20] when the transformer lead wire is led out from the cylinder wall, the tube wall or the side wall [20] contacting the air of the transformer, and thereby, the creepage distance and the insulation level can be increased. The present invention has the advantages that when the structure is adopted, the electric field distribution of the transformer is improved, and the voltage grade of the transformer can be increased.

Description

A kind of external insulation structure of power transformer

Technical field

The present invention relates to a kind of external insulation structure of power transformer.

Background technology

At present, when transformer does not have metal fuel tank and external insulation medium and is air, conventional dry sleeve is generally adopted in the coil outlet, and the lead-in wire that is about to coil directly is connected with dry sleeve, increases creepage distance to reach the purpose that improves transformer external insulation level by the full skirt on the dry sleeve.But this traditional approach of dry sleeve is set to be had the following disadvantages: be the outer limit size that has strengthened whole transformer on the one hand, be because coil lead is direct and the dry sleeve sealing on the other hand, what sealing place was generally adopted is the insulation of fluid sealant class, when the transformer rated voltage is higher, sealing place is easy to generate partial discharge, even puncture, this has limited the raising of the electric pressure of transformer.

Summary of the invention

For overcoming the deficiency of existing transformer aspect above-mentioned, further improve the electric pressure of transformer, the present invention proposes the external insulation structure of a kind of power transformer in air side, adopt this structure the transformer grade of rated voltage can be brought up to 550kV.

When transformer does not have the metal fuel tank, because the external insulation medium is an air, for the tap lead of the head end that increases high pressure, middle pressure, low pressure and neutral point to the air insulation of other current potential positions along the face creepage distance, when the present invention contacts transformer lead from transformer with air barrel or tube wall are drawn, directly being close to transformer lead outside barrel or tube wall is provided with the insulator of being made up of big full skirt and umbellule skirt, so that the increase creepage distance improves insulation level.(full skirt herein and the full skirt same meaning on the bushing shell for transformer).Because full skirt is set directly on the wall of transformer coil, compare with traditional dry sleeve technology on the one hand, the outer limit size of transformer obviously reduces.On the other hand between the coil wall of transformer and the full skirt or be exactly one originally, or by the higher solid packing filling of insulation level, also fill between transformer coil lead-in wire and the full skirt, avoided sealing place of traditional sleeve a little less than the insulation level relative thin to be easy to generate the problem of partial discharge and insulation breakdown by the higher solid packing of insulation level.

The transformer lead-out wire method that the present invention adopts can be brought up to 550kV with grade of rated voltage.

Description of drawings

The invention will be further described below in conjunction with the drawings and specific embodiments.

Fig. 1 goes out one of line position umbrella skirt construction for transformer of the present invention: big umbellule structural representation: a is a front view, and b is a cutaway view;

Fig. 2 goes out two of line position umbrella skirt construction for transformer of the present invention: umbrella structural representation: a is a front view arbitrarily, and b is a cutaway view;

Among the figure: 10 lead-in wires, 20 barrels or tube wall, 30 little full skirts, 40 big full skirts, 50 insulators.

Embodiment

As depicted in figs. 1 and 2, the coil wall of transformer can be a cylinder type, also can be uneven, or shape arbitrarily; Full skirt can be to be the center equidistant placement to go out line position, as circle, and also equidistant placement not, the arbitrary shape shown in Fig. 2 front view.

When external insulation is air insulation, for the lead-out wire position of the head end, neutral point and the branch wiring that increase high pressure, middle pressure, low pressure in the air insulation of other current potential positions along the face creepage distance, when barrel that contacts with air from transformer at lead-in wire 10 or tube wall (abbreviation barrel, tube wall or sidewall) 20 are drawn, outside barrel, tube wall or sidewall 20, be provided with insulator 50.Insulator 50 is made up of the relative a little bit smaller umbellule skirt 40 with volume of the bigger relatively big full skirt 30 of volume.

As depicted in figs. 1 and 2, what be close to lead-in wire 10 is a big full skirt 30, is close to a umbellule skirt 40 outside the big full skirt 30, is close to a big full skirt 30 outside the umbellule skirt 40, by that analogy; What also can be close to lead-in wire 10 is a umbellule skirt 40, is close to a big full skirt 30 outside the umbellule skirt 40, and then is close to a umbellule skirt 40, by that analogy.Can be one between barrel, tube wall or sidewall 20 and the insulator 50, also can not be one and leave the slit, and fill with solid packing in the slit.Insulator 50 and going between can be filled with solid packing between 10, and the material of solid packing is any.Insulator 50 can be pottery, silicon rubber, epoxy resin or other various solid insulating materials.Insulator 50 also can be all by big full skirt 30 or all form by umbellule skirt 40.The version of full skirt, size, material are any, and the size of each full skirt, shape and material all can be different, the cross sectional shape in the slit between barrel, tube wall or sidewall 20 and the insulator 50 can have any shape, so just make that the envelope at the full skirt edge of cutaway view can be the arbitrary curve among the straight line among Fig. 1, oblique line or Fig. 2 among the figure, the full skirt of the front view among the figure can be circle among Fig. 1 or oval or other arbitrary shapes among Fig. 2 along the limit line.Since the envelope at the full skirt edge on the insulator 50 increased high pressure, middle pressure, low pressure head end, neutral point and branch wiring the lead-out wire position in the air insulation of other current potential positions along the face creepage distance, therefore can improve the insulation level of transformer.

Also can have only a kind of full skirt, i.e. full skirt size homogeneous, or multiple umbrella skirt construction.

Above-mentioned execution mode is all applicable for single-phase transformer and three-phase transformer.

Above-mentioned execution mode is all applicable for on-load tap-changing transformer and No-load changer transformer.

Above-mentioned execution mode is all applicable for two-winding transformer and three-winding transformer.

Above-mentioned execution mode is all applicable for the transformer of the various types of cooling.

The present invention proposes the air side external insulation structure of transformer, both utilized external insulation ripple outlet structure (undaform umbrella skirt construction) to solve the external insulation problem of transformer, improved the electric pressure of transformer.Because the transformer external insulation all is to determine creepagely than distance according to the gradation for surface pollution of environment for use usually, therefore, needs only and rationally to choose umbrella skirt construction and size, just the creepage distance of external insulation can be chosen as the required size of rated voltage 550kV transformer.

Claims

1. an external insulation structure of power transformer is characterized in that being close to the lead-in wire (10) of drawing from transformer barrel, tube wall or sidewall (20) and is provided with insulator (50) outside barrel, tube wall or the sidewall (20) that transformer contacts with air; Insulator (50) is made up of two full skirts, one is big full skirt (30), another is little full skirt (40), the little full skirt of volume ratio (40) of big full skirt (30) is big: a big full skirt (30) is close to lead-in wire (10), the outer little full skirt (40) of being close to of big full skirt (30), little full skirt (40) is outer is close to a big full skirt (30), by that analogy; Also can be that a little full skirt (40) is close to lead-in wire (10), little full skirt (40) is outer be close to a big full skirt (30), and then is close to a little full skirt (40), by that analogy; Insulator (50) also can be all by big full skirt (30) or all form by little full skirt (40); Barrel, tube wall or sidewall (20) and insulator (50) are one, also can leave the slit, and fill with solid packing in the slit; Fill with solid packing between insulator (50) and the lead-in wire (10); The manufacturing materials of insulator (50) is pottery, silicon rubber, epoxy resin or other solid insulating materials.