JP5202188B2 - Resin casting with ground layer - Google Patents

Description

  The present invention relates to a resin casting product provided with a grounding layer formed by applying a conductive paint on the outer peripheral surface of an insulating layer embedded with a central conductor, and in particular, a resin casting with a grounding layer capable of improving gas sealing characteristics Related to goods.

Conventionally, this type of resin casting product with a grounding layer has an insulating layer formed by casting an epoxy resin around the central conductor, and a grounding layer is provided by applying a conductive paint on the outer peripheral surface of the insulating layer. Things are known. Such a resin casting product with a grounding layer includes a T-type bushing used for a gas-insulated switchgear, and is attached to a ceiling board of a box body together with an insulating support of a main circuit conductor, and is an air-gas gas Classification is performed (for example, refer to Patent Document 1).
JP 2007-174817 (4th page, FIG. 1)

  The above-mentioned conventional resin cast product with a ground layer has the following problems. The ground layer is required to have a gas seal characteristic for maintaining airtightness in the box as well as conductivity for maintaining the ground potential of the outer periphery of the insulating layer. However, depending on the formation state, it has been difficult to achieve both characteristics.

  That is, since the conductive paint uses epoxy resin or acrylic resin as a binder for conductive powder such as silver or carbon, if the conductive powder is more than the binder, sufficient conductivity can be obtained, but the conductive powder Are not firmly bonded to each other, making it difficult to obtain gas seal characteristics. On the contrary, when there are few electroconductive powders than a binder, although electroconductive powder mutually adhere | attaches firmly and sufficient gas-seal characteristics are acquired, electroconductivity becomes difficult to be obtained. If the conductivity is not obtained, the electric field distribution in the insulating layer is disturbed, and the insulating layer is deteriorated in insulation.

  The present invention has been made to solve the above problems, and provides a resin casting product with a ground layer provided with a ground layer by applying a conductive paint capable of achieving both conductivity and gas seal characteristics. Objective.

In order to achieve the above object, a resin cast product with a ground layer of the present invention comprises a center conductor, an insulating layer formed by casting around the center conductor, and silver powder on the outer peripheral surface of the insulating layer. together provided by coating the configured conductive coating with an epoxy resin, and a ground layer abutting via an O-ring plate wall, the ground layer, rather than the more the epoxy resin is close to the insulating layer The silver powder is formed so as to increase.

  According to the present invention, since the ground layer is provided such that the closer to the insulating layer, the more conductive powder, and the more the adhesive resin the more the outer surface is, the ground layer is provided with both the conductivity and gas seal characteristics of the ground layer. Can be made.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a resin cast product with a grounding layer according to Example 1 of the present invention will be described with reference to FIGS. 1 is a cross-sectional view showing the configuration of a resin cast product with a ground layer according to Example 1 of the present invention, and FIG. 2 shows the ground layer of the resin cast product with a ground layer according to Example 1 of the present invention. It is an expanded sectional view. A resin cast with a ground layer will be described using a T-shaped bushing.

  As shown in FIG. 1, the T-shaped bushing has a center composed of a cylindrical first central conductor 1a and a rod-shaped second central conductor 1b extending vertically from a substantially central portion of the first central conductor 1a. It comprises a conductor 1 and a substantially T-shaped insulating layer 2 formed by casting an insulating material such as an epoxy resin around the central conductor 1.

  At both ends of the center of the insulating layer 2 of the T-shaped head, a concave and conical interface connecting portion 3 is provided, and a grounding layer 4 formed by applying a conductive paint on the outer peripheral surface is provided. The interface connecting portion 3 is connected to an insulating bus that connects between convex and conical discs (not shown), and is fixed to the buried metal 5. Further, the insulating layer 2 of the T-shaped handle portion is a creeping insulating portion, and an electrical device such as a circuit breaker provided in the box is connected to the exposed end of the second central conductor 1b.

  A box-like wall 6 is provided at an intermediate portion between the T-shaped head and the handle, and airtightness is maintained via an O-ring 7. The head side is in the air, and the handle side is in the gas inside the box. A grounding layer 4 is provided on the surface of the insulating layer 2 with which the O-ring 7 abuts, and gas sealing is performed.

  Here, as shown in FIG. 2, the ground layer 4 is formed by spraying a conductive paint using an adhesive resin 4b such as an epoxy resin or an acrylic resin as a binder on a conductive powder 4a such as silver or copper, and curing. And formed. Then, the closer to the insulating layer 2, the more conductive powder 4 a is present than the adhesive resin 4 b, and conversely, the adhesive resin 4 b increases as the outer surface comes into contact with the panel wall 6.

  This utilizes the fact that the specific gravity of the adhesive resin 4b is smaller than that of the conductive powder 4a. For example, the curing rate of the applied conductive paint is reduced, and the conductive powder 4a having a large specific gravity is precipitated on the insulating layer 2 side. After that, it is cured. Such a hardened state is formed at least in a portion in contact with the panel wall 6.

  As a forming method, the T-shaped bushing shown in FIG. 1 is turned upside down so that the flat portion where the panel wall 6 abuts is directed upward, and the conductive paint is spray-coated. The conductive powder 4a can be precipitated by keeping this state and entering a thermostatic bath set to several tens of degrees Celsius and gradually curing over several hours. Further, after applying the conductive paint, it may be allowed to stand at room temperature for several hours and then cured by heating.

  As the conductive paint, the conductive powder 4a is 60 wt% and the adhesive resin 4b is 40 wt%. The thickness of the ground layer 4 is set to several 100 μm. In addition, when silver is used for the conductive powder 4a, the specific gravity is about 10 when the size of the powder is several tens to several hundreds μm, and when the epoxy resin is used for the adhesive resin 4b, the specific gravity is about 2, and by slowly curing, The conductive powder 4a can be precipitated.

  Thereby, on the insulating layer 2 side of the ground layer 4a, the conductive powder 4a is large and excellent conductivity can be obtained. The potential of the ground layer 4 is fixed by the filling 5. Further, the outer surface of the ground layer 4 has a large amount of the adhesive resin 4b firmly bonded, and particularly the surface in contact with the panel wall 6 improves the adhesion with the O-ring 7 and can improve the airtightness. . The ground layer 4 is provided with a conductive gradient function in the thickness direction.

  According to the resin cast product with the ground layer of Example 1 described above, the ground layer 4 is provided such that the closer to the insulating layer 2, the more conductive powder 4a, and the more the adhesive resin 4b the more the outer surface. Therefore, good conductivity is obtained on the insulating layer 2 side, the electric field distribution in the insulating layer 2 is not disturbed, and a strong adhesive force is obtained on the outer surface side in contact with the panel wall 6 to improve gas sealing characteristics. Can be made.

  In the first embodiment, the resin casting with the ground layer has been described using the T-shaped bushing. However, it is also possible to classify gas-gas such as an insulating spacer that separates one gas chamber from the other gas chamber. Can be used.

  Next, a resin cast product with a grounding layer according to Example 2 of the present invention will be described with reference to FIG. FIG. 3 is an enlarged cross-sectional view showing a ground layer of a resin cast product with a ground layer according to Example 2 of the present invention. The second embodiment is different from the first embodiment in the configuration of the ground layer. In FIG. 3, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 3, a first ground layer 8 is provided on the insulating layer 2 side, and a second ground layer 9 is provided on the outer periphery of the first ground layer 8. The panel wall 6 is in contact with the second ground layer 9 through the O-ring 7.

  The first ground layer 8 uses a conductive paint with a large amount of conductive powder 4a and a small amount of adhesive resin 4b. In the second ground layer 9, a conductive paint is used in which the conductive powder 4 a is less than the first ground layer 8 and the adhesive resin 4 b is more than the first ground layer 8. That is, the first ground layer 8 has excellent conductivity, and the second ground layer 9 has a strong adhesive force.

  According to the resin cast product with the grounding layer of the second embodiment, the same effect as the first embodiment can be obtained.

Sectional drawing which shows the structure of the resin casting product with a grounding layer which concerns on Example 1 of this invention. The expanded sectional view which shows the grounding layer of the resin casting product with a grounding layer which concerns on Example 1 of this invention. The expanded sectional view which shows the grounding layer of the resin casting product with a grounding layer which concerns on Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Center conductor 1a 1st center conductor 1b 2nd center conductor 2 Insulating layer 3 Interface connection part 4 Ground layer 4a Conductive powder 4b Adhesive resin 5 Filling 6 Panel wall 7 O-ring 8 1st ground layer 9 2nd The ground layer

Claims (1)

A central conductor;
An insulating layer formed by casting around the central conductor;
The outer peripheral surface of the insulating layer is provided by applying a conductive paint composed of silver powder and epoxy resin, and includes a grounding layer that comes into contact with the panel wall via an O-ring,
The grounding layer is formed such that the closer to the insulating layer, the larger the amount of the silver powder than the epoxy resin is.

Images