JPH0132648Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a bushing used on the high voltage side of a transformer installed on a power distribution line.

Conventionally, a relatively large capacity transformer installed on a power distribution line has bushings 2 on a cover 1 of a transformer case (not shown), as shown in Fig. 1.
is mounted vertically, and the outer surface a of the part of the bushing 2 that protrudes upward from the cover 1 is provided with pleats to provide a sufficient insulation distance.
The inner surface b of the bushing 2 through which the lead wire 3 passes is formed into a flat cylindrical shape, and if a sufficient insulation distance is provided, the bushing becomes long.
Therefore, if an abnormal voltage such as a lightning surge enters the bushing 2 from an external conductor (not shown), the mounting flange of the connecting fitting 4 installed in the bushing 2 to connect the external conductor and the lead wire 3 will be damaged. 4a
becomes the discharge electrode. For this reason, for example, when insulating oil is sealed in the bushing, such as in a sealed transformer equipped with a conservator, since the inside of the bushing is insulated by the insulating oil, Although it is rare that an internal flash fault occurs between the inner surface of the bushing and the cover 1 due to the discharge of When the lower end of the inner protrusion 2C of the bushing 2 that protrudes from the inside is located above the surface of the insulating oil 6 in the transformer, internal flashing occurs along the inner surface b of the bushing 2 and the cover 1. Since there are cases where a short circuit A occurs and the insulation coordination between the inside and outside of the transformer is broken, normally the dimension 6 and set the internal flash value reasonably. However, Bushing 2
If the dimensions of the inner protrusion 2C of the bushing 2 are increased, the bushing 2 will become larger and the cost will increase, and a sufficient insulation distance will be required between the inner protrusion 2C of the bushing 2 and the inside of the transformer (not shown). In the case of
This was a factor that increased the manufacturing cost of transformers.

The present invention eliminates the above-mentioned drawbacks and shortens the dimensions of the inner protrusion of the bushing, thereby reliably preventing internal flash shorts and coordinating the insulation between the inside and outside of the transformer without increasing the size of the transformer. An embodiment of the present invention will be described below with reference to FIG. 2, using the same reference numerals for the same items.

In FIG. 2, the bushing 2 is mounted on the cover 1 by means of a mounting bracket 7, projecting vertically, and inside this bushing 2, a connecting bracket 4 is provided.
are latched by the mounting collar 4a, the outward protruding end of the connecting fitting 4 is passed through and protruded from the head of the bushing 2, and the packing 8,
By tightening the nut 10 through the presser metal fitting 9, it is adhered to the bushing 2, and the inner end of the connecting metal fitting 4 is crimped or otherwise bonded to the conductive part of the lead wire 3 which is connected to a coil (not shown). connected by means. The connecting fitting 4 is attached to the bushing 2 by engaging the bulge 4b formed on the conductor above the mounting collar 4a of the connecting fitting 4 with the vertical groove 2d formed in the small diameter through hole of the head of the bushing 2. is non-rotatably mounted. As shown in FIG.
The lower part is open and the upper part is the mounting collar part 4a facing inward.
A flange edge 11a is formed to the extent that it can be engaged with the upper end edge, and a through hole is provided inwardly of the flange edge 11a through which a conductor portion passing through the head of the bushing 2 can be inserted, as shown in FIG. An open insulation protection tube 11 having a substantially bottomed cylindrical shape is clamped at the flange edge 11a between the inner end of the bushing 2 and the mounting flange 4a, and the insulation protection tube 11 and the inside of the bushing 2 are held together. It is loosely mated to the connecting fitting 4 while covering the live part E and a part of the lead wire 3 while keeping a small gap S between it and the side surface b. The insulation protection tube 11 is made of a synthetic resin with excellent insulation and oil resistance, and the space between the insulation protection tube 11 and the connecting fitting 4 is made of synthetic resin with excellent oil resistance and weather resistance. The resin insulating layer 12 is formed by filling and solidifying the resin and partially embedding the connection fitting 4 and the lead wire 3.

As explained above, in the present invention, the connecting fitting 4 connected to the inner end of the bushing 2 via the mounting flange 4a is provided with a flange 11a that is open at the bottom and engages with the mounting flange 4a at the top. Bottomed cylindrical insulation protection tube 1
1, the connecting fitting 4 with the flange 11a sandwiched between the mounting flange 4a and the inner end of the bushing 2, and a part of the lead wire 3 connected to the connecting fitting 4. The space between the insulation protection cylinder 11 and the connection fitting 4 is filled with oil-resistant synthetic resin and solidified to completely embed the connection fitting 4 and a part of the lead wire 3. Since it is configured to form the insulating layer 12, it has the following effects.

In the present invention, a connecting fitting 4 connected to an external conductor and a lead wire 3 is completely enclosed within a resin insulating layer 12 formed by filling the space between the connecting fitting 4 and an insulating protection tube 11 loosely fitted with resin. Therefore, even if an abnormal voltage intrudes into the bushing 2 from an external conductor (not shown) during a lightning strike, local discharge will not occur within the bushing 2 from the connection fitting 4, and as a result, It is possible to reliably prevent internal flashover from occurring on the inner surface of the bushing 2 due to the infiltration of abnormal voltage.

In addition, an insulation protection tube 11 that covers the connection fitting 4
connects the flange 11a provided on the top of the connecting fitting 4.
Since it is sandwiched between the mounting flange 4a and the inner end of the bushing 2 and loosely fitted to the connection fitting 4, when filling the synthetic resin, the insulation protection cylinder 1
1 is held concentrically with the connecting fitting 4 without swinging, and can be filled with resin with the opening at the bottom facing upward. Since the resin is blocked by the flange 11a of the insulation protection cylinder 11 and does not leak to the outside, the resin insulation layer 12 for embedding the connection fitting 4 can be formed without using a special casting mold. It can be formed easily and economically. Furthermore, the filling resin is received by the flange 11a of the insulation protection tube 11 and does not leak outside, so the small gap S between the insulation protection tube 11 and the inner surface b of the bushing 2 is There is no blockage caused by leakage, and as a result, when the bushing 2 is damaged, the connection fitting 4 can be easily removed without any hindrance when the bushing 2 is damaged. can be quickly and easily reassembled.

Furthermore, in the present invention, since the connecting portion between the connecting fitting 4 and the lead wire 3 is completely embedded in the thick resin insulating layer 12, the connecting fitting 4 of the lead wire 3
It is possible to strengthen the mechanical strength at the connection part. Moreover, since the connecting fitting 4 is embedded in a thick resin insulating layer 12 between it and the inner surface b of the bushing 2, it is possible to significantly increase the insulation strength at the corners of the connecting fitting 4 where electrical discharge is likely to occur. As a result, it is possible to prevent corona discharge in the 4 parts of the connecting fittings, thereby increasing the corona resistance characteristics, and increasing the flashover value without increasing the inner dimensions of the bushing 2. This allows smooth coordination of internal and external insulation. Moreover, since the resin insulating layer 12 is made thick, it will not deteriorate or be damaged by the heat cycle caused by the energization of the connecting fitting 4, and can maintain good insulation of the bushing 2 for many years. can.

As described above, in the present invention, the outer periphery of the connecting fitting 4 is covered with the insulating protection tube 11 and the resin insulating layer 12 to strengthen the mechanical and dielectric strength. Since the flash fault value can be set rationally without immersing the lower end of the inner protrusion 2C protruding inwardly in the cover 1, the bushing 2 It is now possible to make the dimension Y significantly smaller than before, and for this reason,
Since the bushing can be made smaller and the height or width of the transformer case can be reduced,
This method has many excellent effects, such as being able to economically manufacture the transformer without increasing its size and reducing its weight.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a main part of a conventional bushing, and FIG. 2 is a longitudinal cross-sectional view of a main part of a high-pressure bushing according to the present invention. DESCRIPTION OF SYMBOLS 1... Bushing, 4... Connection fitting, 11... Insulation protection cylinder, 12... Resin insulation layer, E... Live part, S... Small gap.

Claims (1)

[Scope of utility model registration request] The outward protruding end of the conductor part to be connected to the external conductor was made to penetrate and protrude outward from the head of the bushing 2, and the conductive part of the lead wire inserted from the lower part was connected to the inner end of the bushing 2 by crimping or the like. Connection fitting 4
is fixed to the inner end of the bushing 2 via the mounting flange 4a, and the outer periphery of the connection fitting 4 has a flange 11a that engages with the upper edge of the mounting flange 4a,
In addition, a bottomed cylindrical insulation protection tube 11 having a through hole through which the conductor passes is sandwiched between the inner end of the bushing 2 and the mounting flange 4a at the flange edge 11a to form the connection fitting. 4, and the space between the insulation protection tube 11 and the connection fitting 4 is filled with synthetic resin to form a resin insulating layer 12 with the connection fitting embedding therein. A high-voltage bushing for electrical equipment characterized by: