JPS6372105A - Insulating structure of lead wire - Google Patents

Abstract

PURPOSE:To improve the dielectric strength of a lead wire by a method wherein a part of the insulation at the middle part of a lead wire, i.e. the connection part or bending part, is composed of an insulating layer which is continuous with the insulating layers of the other parts. CONSTITUTION:After a transformer is installed, connecting conductors 5a and 5b are connected. After 1st insulation 7c is applied by taping to the part between 2nd insulation 7a and 3rd insulation 7b, a continuous insulating layer 9a is formed by taping over the connected middle part B and the other parts of a lead wire 3. With this construction, the insulations are mutually bound mechanically and oil gaps are not created between the insulations even if a little external force is applied. Moreover, with this construction, as the surface part of the conductor, where an electric field is highest, is covered with an insulating layer 9b, even if a fine oil gap is created between the insulations, partial discharge is suppressed. With this constitution, the dielectric strength and the mechanical strength of the lead wire can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lead wire insulation structure for a static inductor such as a transformer, and more particularly to a lead wire insulation structure that improves the dielectric strength of the lead wire.

A conventional static inductor of this type, in particular a transformer by way of example, is illustrated in FIGS. 1, 2 and 3. In Figure 1, (1) is the transformer coil, (2) is the bushing,
(3) is a lead wire, and (4) is a tank.

As shown in FIG. 1, the transformer is provided with a lead wire (3) in the DC link (4) for guiding the current of the coil (1) to the bushing (2). ) is divided into two at the middle part (■) and a connection part is provided as shown in Figure 2, or a lead wire is installed at the middle part (■) due to structure, work, or railway transportation limitations. It is necessary to remove the insulator (3) and bend it.

Figure 2 shows the case where the lead wire (3) is divided into two parts during transportation, for example, it is made up of four connections (5a) and (5b) made of two twisted wires or flat copper wires. , and a first insulating material (7c) such as crepe paper is placed in advance around the middle portion ■ and the connecting conductors on both sides thereof.
and second. Third insulators (7a) (7b) are taped. The first insulator (
7c) is removed, and the lead wire (3) is inserted in the middle part ■.
It can be divided into Furthermore, when installing the transformer after transportation, the connection terminals (6a) and (6b) attached to the tips of the connection conductors (5a) and (5b) are electrically connected at the intermediate portion (■), and the The first insulator (7
c) Taping 1 Figure 3 shows how to tape the lead wire (3) during transportation.
) is folded, and the first insulator (7c) in the center, which is taped around the connecting conductor (5) made of, for example, a twisting wire, is the lead wire (3) before transportation. is removed so that it can be bent, leaving the second insulator (7a) and third insulator (7b) on either side of the fold.

During on-site assembly, the lead wire (3) is stretched back to its original state and the first insulator (7c) is taped around the bent portion.

However, the middle part (■) of the lead wire (3) as described above has a bamboo-like shape, and therefore the second and third
between the insulators (7a), (7b) and the first insulator (7c) taped between them, there may be a gap between the insulators (7a) and (7b) and the first insulator (7c) that is disconnected from the conductor surface due to problems with work or shrinkage due to drying of the middle part (2).
A minute oil gap (8) may occur that continues to the surface of the sewing item. If such a minute oil gap (8) occurs, when a high voltage is applied to the lead wire (3), a partial discharge will occur in the minute oil gap (8), especially near the conductor surface where the electric field is highest. There was a drawback that the lead wire (3) eventually suffered dielectric breakdown from this part.

This invention was made in order to eliminate the drawbacks mentioned above, and it is necessary to make a part of the insulating material at the middle part of the lead wire, that is, the connecting part or the bending part, continuous with the insulating layer in other parts. It is an object of the present invention to provide an insulating structure for a lead wire that improves the dielectric strength of the lead wire (3).

Embodiments of this invention will be described below with reference to FIGS. 4, 5, and 6.
This will be explained with a diagram.

FIG. 4 is an enlarged cross-sectional view of the middle portion (3) of the lead wire (3) which is divided into two parts during transportation, and the continuous insulating layer is indicated by the symbol (9a).

As shown in Figure 4, the connection conductor (5
Connect a) and (5b) to form the second insulator (7a)
and the first insulator (7c) between the third insulator (7b)
After taping, taping is performed over the entirety of the intermediate part (2) where the connection was made and other parts of the lead wire (3) (for example, from the base of the coil (1) to the bushing connection part) to form a continuous insulating layer ( 9a). As a result, the insulators are mechanically restrained, and even if a small amount of external force is applied, no oil gap will occur between them.

FIG. 5 is an enlarged cross-sectional view of the intermediate portion of the lead wire (3) which is bent during transportation, and the continuous insulating layer is indicated by the reference numeral (9b).

In the case shown in Fig. 5, when the taping at the bent part is removed prior to transportation, the thickness of the insulating layer in contact with the lead wire (3) is left so that it will not damage the insulating layer when it is bent. After stretching the bent part during installation, the continuous wire 11i1 is used as an inner continuous insulating layer (9b).
A first insulator (7c) is taped to the outer part of (9b).

According to this structure, even if a minute oil gap occurs between the insulators, the part f of the conductor surface where the electric field is highest is the absolute R layer (9b
), the occurrence of partial number 〒 is suppressed.

FIG. 6 shows an example in which, in addition to the inner continuous insulating layer (9b) shown in FIG. 5, the outer continuous insulating layer (9a) shown in FIG. 4 is also applied.

As explained above, in the case where the lead wire constructed according to the present invention is provided with the outer continuous insulating layer (9a), minute oil gaps are not generated due to the restraint by the insulating layer (9a), and In the case where the inner continuous R layer (9b) is provided, the conductor surface, which is the electrically weakest point, is connected to the layer (9b).
Because it is covered with b), there are no minute oil gaps on the conductor surface.
Therefore, the dielectric strength and mechanical strength of the lead wire are improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a part of a general static inductor; FIGS. 2 and 3 are cross-sectional views of a lead wire for explaining a conventional method of insulating the lead wire; 4 to 6 are cross-sectional views of the lead wire for explaining the method of cutting and sewing the lead wire according to the present invention. In the figure, (3) is the lead wire, (s), (5a)
and (5b) C connecting conductor, (6a) and (6b) connecting terminals, and (7a). (7b) and (7c) are insulators (M, faint line layer), (
9a) and (9b) are the outer and inner continuous insulating layers respectively.

Claims (1)

[Claims] The middle part of the lead wire is a connection part that can be separated and connected for transportation of the device, etc., and the middle part is in contact with a first insulator formed in the middle part and both ends of this first insulator, respectively. In the insulating structure of the lead wire composed of second and third insulators formed in the non-containing portion, the respective insulators are mechanically bonded to each other on the outer surface of the first to third insulators. An insulating structure for a lead wire, characterized by comprising an insulating layer formed continuously so as to be restrained.