JPH0229620Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improved structure of a bushing combined with an insulator for low voltage and large current. This type of bushing is desired to be small and inexpensive, and to ensure oil tightness since it is generally installed in a tank with an oil level above the bushing. FIG. 1 is a structural example of a conventional bushing of this type.

The bushing is provided on one surface 2 of a mounting plate 1 such as a terminal plate made of a non-magnetic material, perpendicular to its axial direction, and is made of an external hollow insulator 5 having a mounting surface 4 that is tightly abutted via a packing 3.
, an internal hollow insulator 7 facing the insulator and having one end surface 6 in the axial direction disposed on the other surface of the mounting plate 1;
It is provided with a round bar central conductor 8 that passes through. A part of the external insulator 1 extends to the part where the central conductor 8 passes through the mounting plate 1 to provide insulation between the two, except for extremely low voltage applications. An L-shaped internal insulator 9 is fixed to the lower end of the central conductor 8 with one side perpendicular to the axis of the conductor 8, and the one side abuts the other axial end surface of the internal insulator 7 via a cushion 10. . A seat plate 13 is disposed on the axially outer end face 11 of the external insulator 5 and has a packing 12 for tightly sealing the face, and is penetrated by the central conductor 8.
A packing 14 that tightly seals the space between the packing 14, a push plate 15 that presses the packing, and a nut 16 that engages the push plate with a screw provided at the outer end of the central conductor 8 and presses it in the direction of the external insulator 5. will be arranged. Additionally, the outer threaded end of the central conductor is provided with an external terminal 17 and a locking nut 18 for axially pressing the terminal.

As described above, conventional bushings are small and do not require mounting space, especially since they do not have seats for mounting insulators, and are used in transformers for large current rectifiers, etc., which require a large number of bushings. However, the number of parts used was large, and many of them required time to process, making them expensive. Further, when the central conductor 8 is overheated and expanded due to the current, the pressing force of the packings 3 and 12 is reduced, causing the insulating medium such as oil sealed inside to leak from the packing portion. The purpose of this invention is to eliminate these conventional drawbacks and provide a low-voltage, high-current bushing that is inexpensive because it requires fewer parts and processing time, and that does not leak the internal insulating medium due to overheating of the current. shall be.
According to this invention, this object was achieved by the following configuration. That is, an external insulator whose mounting surface is in close contact with one surface of the mounting plate through a gasket and is hollow in the axial direction, and an external insulator which is disposed on the other side of the mounting plate facing the external insulator and which is hollow in the axial direction. an internal insulator that is hollow, and an end that penetrates through the hollow portions of both of the insulators and the mounting plate, has connecting portions at both ends thereof, and tightly closes an axially outer end surface of the external insulator through a packing. A bushing for an electrical device that includes a central conductor having a plate and an insulating medium enclosed inside the bushing includes a rod body disposed in the hollow part of both the insulators and one end of which engages the end plate; a holding plate that engages with the other end and abuts the axial end surface of the internal insulator, the central conductor is closely coupled to the penetrating end plate and passes through the holding plate with a space therebetween; The rod and the holding plate clamp the insulators to the mounting plate.

In this way, the clamping force between the mounting plate and both insulators is not affected by changes in the dimensions of the central conductor.

In the hollow part of the insulator, the central conductor is preferably a rectangular conductor in order to arrange the tightening rod.

FIGS. 2 and 3 are structural diagrams of an embodiment of the invention. The same reference numerals indicate those having the same effect as the previous one. The parts of this bushing include an external insulator 5 which is provided on one surface 2 of the mounting plate 1 at right angles to its axial direction and has a mounting surface 4 that is closely abutted via a packing 3; An internal insulator 7 whose one end surface 6 in the axial direction abuts against the other surface 2' of the mounting plate 1 via a cushion.
and a central conductor 21 which is a rectangular conductor passing through the hollow portions 5' of both insulators 5 and 7 and the mounting plate 1 in the axial direction of both insulators. The central conductor 21 is tightly coupled by brazing to an end plate 22 penetrated by the conductor, and the end plate 22 tightly closes the outer end surface 11 of the external insulator 5 via the packing 12. central conductor 2
Holes 23 are formed at both ends of the conductor 1 to serve as connection parts with other conductors. In addition, there is a holding plate 25 which is in contact with the other end surface 24 in the axial direction of the internal insulator 7 via a cushion (not shown) and which is penetrated through the central conductor 21, and one end is attached to the end plate 22 in the hollow part 5' of the insulators 5, 7. A threaded rod 27 is fixed by a screw or the like, and the other end of the rod 27 passes through the presser plate 25 and engages with the presser plate via a nut 26. By tightening the nut 26, the insulators 5 and 7 are assembled together. The nut 26 and the threaded rod 27 may be replaced with bolts, or the end plate 22 and the threaded rod 27 may be engaged by welding.

By configuring as described above, that is, by using a rectangular conductor as the central conductor, both ends of the conductor can be used as connection parts, so it is not necessary to provide an internal terminal as in the conventional case, or to use an external terminal and its lock nut. It becomes unnecessary. Further, by tightly coupling the end plate 22 to the central conductor 21 to close the outer end surface 11 of the external insulator 5, it is no longer necessary to cut the gasket, its push plate, nut, and thread into the central conductor as in the conventional case. Also, both insulators 5 and 7
The central conductor 21 is sandwiched between both plates 22 and 25 and tightened with a threaded rod 27 to form a single body.
The expansion and contraction due to heat is caused by the expansion and contraction of the outer insulator 5's gaskets 3 and 12.
The central conductor 2 has no effect on the pressing force of the central conductor 2.
The current of 1 will not cause leakage of the internal fluid of the packing part.

As is clear from the above description, the configuration of this invention makes it possible to obtain a bushing that is small, inexpensive, and in which the current flowing through the central conductor does not cause leakage of the insulating medium.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of a conventional bushing for low voltage and high current combined with insulators, FIG. 2 is a vertical sectional view of an embodiment of this invention, and FIG. 3 is a plan view of FIG. 2. 1: Mounting plate, 2: One side of mounting plate, 4: Mounting surface of external insulator, 5: External insulator, 5': Hollow part, 7: Internal insulator, 11: Outer end surface of external insulator,
21: central conductor, 22: end plate, 24: other end surface of internal insulator, 25: holding plate, 27: threaded rod.

Claims (1)

[Scope of utility model registration request] an external insulator whose mounting surface is in close contact with one surface of the mounting plate through a gasket, and which is hollow in the axial direction; an internal insulator that is hollow; and an end plate that penetrates through the hollow parts of both the insulators and the mounting plate, has connection parts at both ends thereof, and tightly closes the axially outer end surface of the external insulator through a packing. A bushing for an electrical device having a central conductor having a central conductor and an insulating medium sealed inside the bushing includes a rod disposed in the hollow part of the insulators and one end of which engages with the end plate; a retainer plate that engages with the end portion and abuts against the axial end surface of the internal insulator; A bushing combining insulators, characterized in that a rod body and a holding plate fasten both the insulators to a mounting plate.