JPH03225778A - Insulating method of lead wire connecting part - Google Patents

Abstract

PURPOSE:To efficiently insulate a connecting a part by providing a thermally shrinkable tube to cover the lead wire connecting part of a high voltage electric apparatus, charging silicon gel in the tube followed by hardening, and thermally shrinking the tube close to silicon gel. CONSTITUTION:In the example of a dry transformer, a thermally shrinkable tube 22 is fitted to a high voltage lead wire 16 before the bolt 19 and nut 20 of a lead connecting part 21 are fastened. After the fastening of the bolt 19 and nut 20, the tube 22 is moved to enclose the connecting part 21 and the lower end part 15a of a high voltage bushing 15 (two-dot chain line), and only the lower end part is heated and shrunk to form a vessel. After silicon gel 23 therein is hardened into a gelatinous form at ordinary temperature or by heating, the tube 22 is heated and shrunk successively from the lower part toward the upper part and closely adhered to the gel 23 while pushing out the air in the inner part, and the upper end part of the tube is finally heated and shrunk.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention (Industrial Application Field) The present invention relates to a method for insulating a lead wire connection portion of a high-voltage electrical device.

(Conventional technology) The electrical distribution equipment in the building is air conditioning equipment and lighting equipment.

With the automation of other equipment, the installation of various office equipment, and the rise of buildings, their capacity tends to increase.
For example, high-voltage, large-capacity dry transformers, which are high-voltage electrical equipment, have been used from an economic standpoint. On the other hand, with the rise in land prices mainly in the Tokyo metropolitan area, there is a desire to reduce the installation area of dry-type transformers in order to effectively utilize the floor space of buildings, etc. For this reason,
Traditionally, the so-called lead wire connections, for example, the connections between the high voltage lead wires of dry type transformers and high voltage bushings, cable heads, bushings of new line equipment, etc., have been insulated to shorten the insulation distance of the lead wire connections. Attempts are being made to reduce the overall size.

That is, FIG. 7 shows the first conventional example, in which a crimp terminal 4 is attached to the lower end of the center conductor 2 of the high voltage bushing 1 at the tip of the high voltage lead wire 3, and is tightened with a bolt 5 and a nut 6 to connect the lead. A wire connection portion 7 is formed, and a mica insulating tape or self-fusion tape 8 is wrapped around the lead wire connection portion 7 so as to cover the entire lead wire connection portion 7.

FIG. 8 shows a second conventional example, in which high voltage lead wires 3.
The crimp terminals 4, 4 attached to the ends of 3 are tightened with bolts 5 and nuts 6 to form a lead wire connection section 9, and a mica insulating tape or self-fusing tape 8 is applied to cover the entire lead wire connection section 9. is wrapped around it.

In addition, as a third conventional example, instead of wrapping mica insulating tape or self-fusing tape 8, a heat shrink tube is placed to cover the entire lead wire connection portions 7 and 9, and the heat shrink tube is shrunk for insulation. Sometimes.

(Problem to be solved by the invention) The above configuration has the following problems.

That is, in the first and second conventional examples, the lower end 1a of the high-voltage bushing 1 has a large diameter, the center conductor 2 and the high-voltage lead wire 3 have a small diameter, and the bolt 5 and nut 6 in the middle part have a large diameter. Since the tape 8 has a complex shape as a whole, such as protruding from the sides, it is difficult to wrap the tape 8 around the lead wire connection parts 7 and 9. Poor workability. Furthermore, a gap is likely to be formed between the tape 8 and the lead wire connection portion 7.9, and the air layer in this gap reduces dielectric strength.

In the third conventional example, the heat-shrinkable tube that replaces the tape 8 has a wall thickness of about 3 to 5 watts after heat-shrinking, making it impossible to obtain sufficient dielectric strength.

As a result, in any case, the insulation distance of the lead wire connection portion 7.9 must be set to be large, which is insufficient to achieve overall miniaturization.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to increase the dielectric strength of the high-voltage lead wire connection portion, to downsize the entire high-voltage electrical equipment, and to connect the lead wires with ease of operation. This section provides an insulation method.

[Structure of the Invention (Means for Solving the Problems) The method of insulating the lead wire connection portion of the present invention is to provide a heat shrink tube so as to cover the lead wire connection portion of a high voltage electrical device, and to insulate the lead wire connection portion in the heat shrink tube. It is characterized in that it is filled with silicone gel and cured, and the heat-shrinkable tube is heat-shrinked so as to come into close contact with the silicone gel.

(Function) The method of insulating the lead wire connection part of the present invention is such that the silicone gel filled in a heat-shrinkable tube and hardened covers the lead wire connection part of a high-voltage electrical device without any gaps and is tightly attached to the silicone gel. Since the heat-shrinkable tube is heat-shrinkable, it is possible to increase the dielectric strength even if the shape of the lead wire connection part is complex, and the work of filling and curing silicone gel can be done without the need for special tools. , can be easily done.

(Example) Hereinafter, an example in which the present invention is applied to a dry type transformer will be described with reference to FIGS. 1 to 3.

Transformer main body 13 composed of iron core 11 and coil 12
is arranged in the transformer panel 14, and this transformer panel 14
A high-pressure bushing 15 is attached to the upper surface portion 14a. A crimp terminal 17 is attached to the tip of the high voltage lead wire 16 drawn out from the coil 12.
is fastened to the lower end of the center conductor 18 of the high voltage bushing 15 with a bolt 19 and a nut 20, thereby forming a lead wire connection portion 21. The silicone heat shrink tube 22 is fitted onto the high voltage lead wire 16 in advance before the bolts 19 and nuts 20 are tightened. and,
This heat shrink tube 22 is used to attach bolts 19 and nuts 20.
After that, tighten the lead wire connection part 21 and high pressure bushing 1.
5 (indicated by the two-dot chain line), and only the lower end is heated and shrunk to form a container shape.

Next, the silicone gel 23 is filled up to the lower end 15a of the high-pressure bushing 15 so as to cover the outer periphery of the lead wire connection part 21. This silicone gel 23 is a two-component product in which liquid A and liquid B are mixed at a weight ratio of 1:1, and as shown in FIG. Excellent isoelectric properties and high upper limit of operating temperature range. Moreover, the viscosity of silicone gel 23 is 84 at 25°C.
The curing speed is as low as 0 centipoise (70℃XQ).

5 hours, 25°C x 16 hours), which is faster than epoxy resin. After this silicone gel 23 is hardened to an agar-like shape at room temperature or heated, the heat shrink tube 2
2 is heat-shrinked sequentially from the bottom to the top to expel the air inside and bring it into close contact with the silicone gel 23. Finally, the upper end of the heat-shrinkable tube 22 is heated and shrunk.

According to the above embodiment, the silicone gel 23 is filled into the heat-shrinkable tube 22 that covers the outer periphery of the lead wire connection part 21 and cured, and the heat-shrinkable tube 22 is heat-shrinked so as to come into close contact with the silicone gel 23. I let it happen. In this case, as shown in FIG. 3, the silicone gel 23 has excellent electrical properties such as dielectric breakdown value, volume resistivity, dielectric constant, and dielectric loss tangent, and has a high upper limit of the operating temperature range.
The viscosity is as low as 840 centipoise at 25°C, and it penetrates into the details of the lead wire connection part 21, which has a complex shape. Therefore, a sufficient insulation distance can be maintained, and the dielectric strength can be significantly improved. . This results in
It becomes possible to reduce the insulation distance between the lead wire connecting portions 21 or between the lead wire connecting portions 21 and the iron core 11 and the transformer panel 14 serving as the ground, and the transformer panel 14 can be made smaller. In addition, it is sufficient to make the heat shrink tube 22 into a container shape and then fill it with the silicone gel 23.
There is no need for tools such as a special container, and there is no need to wind the tape, so the work can be done easily. Moreover, silicone gel 23 is soft (
Since the silicone gel has a hardness of JISA 1), it is easy to remove the silicone gel 23 to inspect the lead wire connection portion 21.

Figures 4 and 5 show another embodiment in which the present invention is applied to connecting high voltage lead wires 16 together. Attach the crimp terminals 17, 17 to the bolt 19 and nut 2.
0 to form a lead wire connection portion 24, and a heat shrink tube 25 is attached so as to surround this lead wire connection portion 24.
After the silicone gel 26 is filled and cured, the heat-shrinkable tube 25 is heated and shrunk.

This embodiment also provides the same effects as the above embodiment.

Furthermore, as shown in FIG. 6, a thermolabel 2 is attached to the crimp terminal 17.
7, the temperature of the connection part can be visually observed from the outside through the transparent silicone gel 26 and heat shrink tube 25, and abnormalities in heat generation can be detected, thereby increasing the safety of the equipment. can.

[Effects of the Invention] The method of insulating the lead wire connection portion of the present invention includes providing a heat shrink tube to cover the lead wire connection portion of a high-voltage electrical device, filling the heat shrink tube with silicone gel and curing it. Since the heat-shrinkable tube is heat-shrinked so as to adhere tightly to the silicone gel, the dielectric strength can be increased even if the shape of the lead wire connection part is complex, and the overall size of the high-voltage electrical equipment can be reduced. , it has the effect of being easy to work with.

[Brief explanation of drawings]

Figures 1 to 3 show one embodiment of the present invention. Figure 1 is an enlarged sectional view of the main parts, Figure 2 is a longitudinal sectional view of the entire dry type transformer, and Figure 3 is a silicone gel It is a characteristic comparison diagram,
4 to 6 are views corresponding to FIG. 1 in different operating states showing other embodiments of the present invention, and FIGS. 7 and 8 are views corresponding to FIGS. 1 and 5 of the conventional example. In the figure, 15 is a high pressure bushing, 16 is a high voltage lead wire, 2
1 is a lead wire connection portion, 22 is a heat shrink tube, 23 is a silicone gel, 24 is a lead wire connection portion, 25 is a heat shrink tube, and 26 is a silicone gel.

Claims (1)

[Claims] 1. A heat-shrinkable tube is provided to cover the lead wire connection portion of the high-voltage electrical equipment, and silicone gel is filled into this heat-shrinkable tube and cured, and the heat-shrinkable tube is heat-shrinked so as to tightly adhere to the silicone gel. A method for insulating a lead wire connection portion, characterized in that: