JPH06349640A - Transformer - Google Patents

Abstract

PURPOSE:To lighten the bending stress imposed on insulating studs due to the tank elastic deformation during the vacuum deaerating step of the tank for avoiding the breakdown of the insulating studs by a method wherein insulating boards are fixed by making gaps between the insulating studs for tightening and fixing the insulating boards. CONSTITUTION:An insulating barrier is composed of a plurality of insulating press boards 10 in thickness of several mm juxtaposed making gaps between respective press boards 10. Next, a plurality of boards 10 are tightened up and fixed on a tank sidewall board by an insulating studs 51. Next, the insulating press boards 10 outside the included front row side board out of the boards 10 is tightened up and fixed by the insulating studs 52 and then outside board 10 is tightened up and fixed by the other insulating studs 53. At this time, the specific dimension between the boards 10 are secured by inserting spacers 7. Through these procedures, the bonding stress imposed on the insulating studs 53 due to the tank elastic deformation during the vacuum deaerating step of the tank can be lightened for avoiding the breakdown of the insulating studs 53.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-high voltage, large capacity transformer of 500 kV or 1000 kV, and more particularly to a transformer having an insulating barrier structure on a tank wall.

[0002]

2. Description of the Related Art With the recent increase in power demand,
Ultra-high voltage transmission of 00kV class has been implemented, and 1000kV class transmission is currently being put to practical use. Such transformers installed in power plants and substations for ultra-high voltage transmission generally have a bank configuration in which a plurality of single-phase units are combined and three-phase wiring is performed to form a three-phase unit. In such a single-phase transformer, due to various transportation restrictions and increase in capacity per unit, the transformer is made compact, and the electrical stress inside each part of the transformer is very high, and the electrical insulation is high. Various measures have been taken against the above. For example, between the winding and the tank inner wall plate, as shown in FIGS. 2 and 3, a plurality of insulating boards are provided between the outer high voltage winding 11 and the tank side wall plate 3 in order to improve the withstand voltage by subdividing the oil gap. Insulating barrier 4 is installed.

The insulating barrier 4 is usually made of a press board having a size of several mm, and a plurality of insulating barriers 4 are insulated from the insulating stud 5 as shown in FIG. 3 while maintaining an appropriate gap in the tank side wall plate 3 facing the outer high voltage winding 11. The nut 6 is tightened and fixed. The insulating stud 5 and the insulating nut 6 are usually processed from an insulating material such as reinforced wood made from wood. Tightening with the insulating studs is performed at a plurality of points on the insulating barrier 4, and if necessary, at a plurality of points inside the insulating barrier. As described above, the transformer contents main body is carefully inserted and fixed in the tank after the insulating barrier is attached to the tank side plate as described above, the cover is placed, and the transformer insulating oil is injected through the vacuum deaeration process.

[0004]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The transformer constructed as described above has the following problems. As mentioned above, the insulating side wall 4 and the insulating stud 5 are attached to the tank side wall plate 3.
After installation, the transformer is vacuum degassed. Although the tank 3 is manufactured to withstand vacuuming, a slight elastic deformation occurs during vacuum processing, and the tank side wall plate is deformed so as to bend inward of the tank. At this time, since tensile stress acts on the insulating barrier 4, a large bending stress acts on the insulating stud 5 that fastens the insulating barrier 4. This bending stress is greater as the insulating stud 5 is longer, so that the higher the voltage class and the greater the number of boards, the greater the bending stress. For this reason, the insulating stud 5 may be damaged by vacuum treatment of the transformer. Therefore, it is necessary to provide a tank structure having high rigidity so that the deformation amount of the tank in vacuum becomes small.

Further, the length of the insulating stud 5 reaches 100 mm to 200 mm in a 1000 kV class transformer due to the structure in which the insulating barrier 4 made up of a plurality of press boards is mounted, and the length of the insulating stud extends in the longitudinal direction. The voltage becomes very large. Since the withstand voltage value of the shared voltage experimentally increases substantially in proportion to the square root of the length, if the length of the insulating stud is large, the shared voltage exceeds the withstand voltage value,
It may cause dielectric breakdown.

The present invention has been made in view of the above points,
It is an object of the present invention to provide a transformer having an insulating barrier structure that has improved mechanical strength against tank deformation and improved withstand voltage performance.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a transformer comprising a winding part wound around an iron core in a tank,
A plurality of insulating boards that electrically insulate and protect the tank side wall plate facing the winding portion are arranged side by side with a plurality of insulating spacers interposed, and the insulating studs that integrally penetrate the insulating spacers and the insulating boards are insulated from each other. An insulating barrier formed by being fixed to the board is fixed to the tank side wall plate. Further, the insulating studs that penetrate the insulating spacers in a juxtaposed direction from the frontmost insulating board facing the tank side wall plate to the last insulating board are used at intervals in the coaxial direction. In the direction, the insulating studs that penetrate the insulating spacers are used to clamp and secure the insulating board at multiple locations.

[0008]

With the structure of the present invention, even when the tank is deformed by vacuuming, the tensile force acting on the insulating barrier is distributed to the plurality of insulating studs, so that the bending stress applied to a single insulating stud is reduced. It is possible to prevent the barria from being damaged.

Further, since a plurality of insulating studs are coaxially used to tighten and fix the boards forming the insulating barrier, the withstand voltage value per stud is reduced.
Since the total withstand voltage of all the plurality is large, the withstand voltage performance of the insulating barrier is also improved.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in FIG. FIG. 1 is a cross-sectional view showing a state in which an insulating barrier according to the present invention is attached to a tank side wall plate.

The insulating barrier 4 is composed of a plurality of insulating pressboards 10 having a thickness of several mm, which are arranged side by side with a gap therebetween. Insulation studs 51 on the tank side wall plate 3
Tighten and fix multiple boards 10 by. Next, the board 10 on the outer side of the board 10 including the board on the front row side is tightened and fixed by the insulating stud 52. Further, a plurality of boards 10 arranged side by side including the board 10 on the outside thereof are tightened and fixed by the insulating studs 53. The gap between the boards 10 has a predetermined size by inserting the spacer 7. The spacer 7 may be formed for each tightening stud, or may be formed as a common rod-shaped spacer between the same boards.

The insulating barrier structure constructed as described above has the following actions. That is, when the inside of the transformer tank is subjected to vacuum deaeration, the tank receives a force f toward the inside as shown in FIG. 4, causing a slight elastic deformation. For this reason, the insulating studs 51 tightened in the tank wall 3 try to face outward with respect to the deformed portion of the tank wall 3, but are pulled inward by the insulating board 41, and bending stress acts. Since this bending stress is proportional to the displacement amount and the length of the insulating stud 51 caused by vacuuming, the displacement of the insulating stud can be changed by using a plurality of insulating studs with coaxial intervals as in the present invention. Both the quantity and the length are small, and therefore the bending stress acting on the insulating stud is small. Also,
Since the insulating stud 52 is fixed to the insulating board 41, not to the tank wall 3, and because the insulating board is somewhat flexible, the insulating board 41 absorbs a part of the displacement of the insulating stud 51 due to vacuuming. As a result, the force acting on the insulating stud 52 becomes weaker, the force acting on the insulating stud 53 becomes weaker, and the force acting on the insulating stud and the board located inside the tank becomes weaker.

As described above, since the insulating studs for clamping and fixing the insulating boards are spaced from each other to fix the insulating boards, the bending which acts on the insulating studs due to the elastic deformation of the tank during the vacuum degassing process of the tank. The stress is small, and damage to the insulating studs can be prevented.

Further, the use of the insulating studs spaced apart from each other is effective not only in terms of mechanical strength, but also in terms of electrical insulation as follows. That is,
Since the withstand voltage of an insulating material is proportional to its length to the power of n (n <1), the larger the length of the insulating stud, the larger the voltage to be shared. Sexuality increases. In particular, in a 1000 kV transformer, the number of insulating boards 4 attached to the tank wall 3 becomes very large, and if the insulating studs are not divided, 1/4 of the outer high voltage winding voltage is applied.
Since 1/2 is shared and electrical insulation cannot be maintained, the use of insulating studs at intervals in the coaxial direction provides a very large effect of preventing discharge.

By using a plurality of insulating studs 5 which are coaxially spaced from each other in the juxtaposed direction of the insulating barriers, the bending stress acting on the insulating studs during the vacuum processing of the tank can be reduced. The tightening structure becomes slightly complicated. As an alternative to this structure, there is a method of using a strong insulating stud itself. For example,
By using an insulating stud made by screwing glass fiber reinforced epoxy resin, it is possible to prevent damage during tank vacuum processing.

By using the insulating studs 5 spaced from each other, the bending stress acting on the insulating studs during the vacuum processing of the tank can be reduced, but as a method of further increasing the structural strength, the maximum bending stress acts on the tank. It is possible to use only glass fiber reinforced epoxy resin for the insulating studs that are directly tightened and fixed to the wall.

[0017]

As described above, according to the present invention,
It is possible to realize a transformer having an insulating barrier structure with improved mechanical strength against tank deformation and improved withstand voltage performance.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an insulated barrier structure of a transformer according to an embodiment of the present invention.

FIG. 2 is a plan view of a transformer in which a conventional insulating barrier is fixed to a tank side wall plate.

3 is a vertical cross-sectional view of the transformer shown in FIG.

FIG. 4 is a view exemplifying the deformation of the tank and the force acting on the insulating stud when the inside of the tank is evacuated by vacuum.

[Explanation of symbols]

1 ... Winding, 2 ... Iron core, 3 ... Tank, 4 ... Insulation barrier,
5 ... Insulation stud, 7 ... Insulation spacer, 41, 42, 43 ... Insulation board, 51, 52, 53, 54, 55 ... Insulation stud.

Claims (3)

[Claims] 1. A transformer comprising a winding part wound around an iron core in a tank, comprising a plurality of insulating boards for electrically insulating and protecting a tank side wall plate facing the winding part. A transformer formed by juxtaposing insulating spacers and juxtaposed with each other, and fixing an insulating barrier formed by fixing insulating studs integrally penetrating the insulating spacer and the insulating board to the insulating board to the tank side wall plate, The insulating studs that penetrate the insulating spacers in a juxtaposed direction from the frontmost insulating board to the last insulating board facing the tank side wall plate are used at intervals in the coaxial direction, and in the insulating barrier vertical direction, The transformer characterized in that the insulating studs penetrating the insulating spacer are used to tighten and fix the insulating board at a plurality of locations. 2. The transformer according to claim 1, wherein the insulating stud is made of glass fiber reinforced epoxy resin. 3. The transformer according to claim 1, wherein only the insulating studs directly fixed to the tank side wall plate are made of glass fiber reinforced epoxy resin.