JP2586995Y2 - Through bushing - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention relates to a through bushing.
The cost is reduced by preventing the mounting flange from being enlarged.

[0002]

2. Description of the Related Art In substation equipment, a penetration bushing is used at a portion where a conductor penetrates a metal plate or the like. FIG. 3 shows the structure of the through bushing. A through hole 2 is formed in a mounting plate 1 serving as a grounding portion, and a bushing 3 formed of an insulating resin having a fold 3a for increasing a creepage distance is coupled to a flange portion 3b via a bolt (not shown). The bushing body 3c is attached to the attachment plate 1 with the bushing body 3c inserted through the through hole 2. A conductor 4 is integrally molded with the bushing 3.

Since the dielectric constant of the insulating resin is four times as large as the dielectric constant in the air, there is a great difference between the dielectric constant and the electric field between the inner peripheral portion of the through hole 2 in the mounting plate 1 and the bushing body 3c. Is concentrated. In order to alleviate this electric field concentration, the distance L between the outer peripheral surface of the bushing main body 3c and the inner peripheral surface of the through hole 2 is increased, and the pointed portion of the mounting plate 1 near the inner peripheral surface of the through hole 2 is sharp. It had a round shape 1a without any. In addition, in order to reduce the electric field concentration, an earth shield may be embedded in the flange portion 3b.

[0004]

However, when the distance L between the outer peripheral surface of the bushing body and the inner peripheral surface of the mounting hole is increased, the outer diameter of the flange portion is increased, and a large mounting space is required. Further, if a round shape is provided in the cross section of the mounting plate, the thickness of the mounting plate is inevitably increased, and the cost is increased.

On the other hand, when burying an earth shield,
An expensive earth shield is required, which increases costs. Further, when a metal is buried in the insulating resin, a thermal stress is generated due to a difference in thermal expansion coefficient between the two, and it is necessary to consider that this thermal stress is smaller than an allowable stress of the insulating resin.

Therefore, an object of the present invention is to provide a through bushing which solves the above problem.

[0007]

In order to achieve the above object, according to the present invention, a through-hole is formed in a mounting plate, and a substantially cylindrical bushing body in which a conductor is molded and a bushing body are integrally formed. The bushing consisting of the flange part
In a through bushing in which the bushing main body is inserted through the through hole and the flange portion and the mounting plate are connected, in the vicinity of the surface of the flange portion where the mounting plate abuts and the outer peripheral surface of the bushing main body where the through hole of the mounting plate faces. And the ground layer is formed, and the end of the ground layer on the side opposite to the flange portion is
It is characterized in that it is covered with insulating resin over the entire circumference of the bushing body .

[0008]

The inner peripheral portion of the through hole in the mounting plate is surrounded by a ground layer having the same potential as the mounting plate. For this reason, electric field concentration does not occur in the inner peripheral portion of the through hole as in the related art.

Further , since the end of the ground layer is covered with the insulating resin, the electric field concentration is also reduced in this portion.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. In this embodiment, since a part of the conventional through bushing is improved, the same reference numerals are given to the same parts as those in the related art, and the description thereof will be omitted, and only different parts will be described.

(A) Embodiment 1 FIG. 1 shows the structure of a through bushing according to the present invention. As shown in the figure, the outer peripheral surface of the bushing body 3c and the mounting plate 1
A U-shaped circumferential groove 5 is formed in a portion facing the through-hole 2 of the first embodiment, and a ground layer 6 is provided on the side and bottom surfaces of the circumferential groove 5 and the surface of the flange portion 3b where the mounting plate 1 contacts. . The grounding layer 6 is made of metallikon or conductive paint or the like, and is provided in close contact with the surface of the bushing 3. Here, metallikon refers to a coating applied to the surface of a member by spraying a metal. The ground layer 6 is provided with the through hole 2 in the mounting plate 1.
Is provided so as to cover the inner peripheral portion. This is to prevent the sectional shape of the inner peripheral portion of the through hole 2 in the mounting plate 1 from affecting the withstand voltage characteristics.

Next, the operation of the through bushing will be described. As shown in the drawing, the inner peripheral portion of the through hole 2 in the mounting plate 1 is in a state of being electrically connected to the mounting plate 1 and surrounded by a ground layer 6 having the same potential as the mounting plate 1. Therefore, the through hole 2
Does not occur in the inner peripheral portion of the conventional device. Therefore, the distance between the inner peripheral surface of the through hole 2 and the outer peripheral surface of the bushing body 3c is increased to increase the outer diameter of the flange portion 3b, or a large radius shape is provided in the inner peripheral portion of the through hole 2. do not have to.

(B) Embodiment 2 This embodiment is a further improvement of Embodiment 1, and therefore only different parts from Embodiment 1 will be described.

As shown in FIG. 2, an insulating resin 7 is coated on the entire outer surface of the ground layer 6 at the end on the side opposite to the flange portion. This is because, by covering the end of the ground layer 6 with an insulating resin having a higher dielectric constant than in the air, the electric field concentration at the end is reduced and the withstand voltage performance is improved. The distance H between the end surface of the ground layer 6 and the outer peripheral surface of the bushing body 3c is 3 to 5 mm.

In such a through bushing, similarly to the first embodiment, not only does electric field concentration not occur on the inner peripheral portion of the through hole 2, but also
Since the end of the ground layer 6 is covered with the insulating resin 7,
Also in this portion, the electric field concentration is reduced. Therefore, Example 1
The withstand voltage performance is further improved as compared with the through bushing.

[0016]

As can be seen from the above description, according to the through bushing of the first aspect, the surface of the flange of the bushing where the mounting plate abuts and the surface of the outer peripheral surface of the bushing body where the through hole of the mounting plate opposes. Since the ground layer is formed in the vicinity, the inner peripheral surface of the through hole in the mounting plate is surrounded by the ground layer having the same potential as the mounting plate. Therefore, electric field concentration does not occur in the inner peripheral portion of the through hole.
Therefore, the outer diameter of the flange portion of the bushing can be reduced as compared with the conventional case, and the cost of the through bushing can be reduced. Further, it is not necessary to provide a large radius shape in the cross section of the inner peripheral portion of the through hole as in the related art, and the cost of the through bushing can be reduced from this surface.

Further, the end of the ground layer on the side opposite to the flange portion is covered with an insulating resin over the entire periphery of the bushing body .
Thus, the electric field concentration is reduced at the end of the ground layer .

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a through bushing according to the present invention.

FIG. 2 is a sectional view showing a main part of a second embodiment of the through bushing according to the present invention;

FIG. 3 is a sectional view of a conventional through bushing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Mounting plate 2 ... Through-hole 3 ... Bushing 3b ... Flange part 3c ... Bushing body 5 ... Circumferential groove 6 ... Grounding layer 7 ... Insulating resin

Continuation of the front page (56) References JP-A-55-130015 (JP, A) JP-A-60-46612 (JP, U) JP-A-63-96719 (JP, U) JP-A-2-14210 (JP) , U) Hikaru 2-104523 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01B 17/26

Claims (1)

(57) [Scope of request for utility model registration] 1. A bushing comprising a through-hole formed in a mounting plate, a substantially cylindrical bushing body molded with a conductor, and a flange integrally formed with the bushing body, wherein the bushing body is inserted through the through-hole. in the through bushing by combining the flange portion and the mounting plate, forming a ground layer in the vicinity of the surface holes of the mounting plate facing the mounting plate on the outer peripheral surface of the abutting surface and the bushing body in the flange portion, the ground layer At the opposite flange side
Cover the end with insulating resin all around the bushing body.
A through bushing characterized in that: