Ngk Insulators, Inc.

Nkg Insulators, Ltd.

Hiroshi Nozaki

Shigeo Mori

Yoshihiro Suzuki

Akihiro Watanabe

Itsushi Nakamura

Tsutomu Moriya

Mitsuharu Okamoto

Eiji Kutsuna

Haruo Inoue

Insulator having conductive surface coating to prevent corona discharge

A suspension insulator having a porcelain insulating member with a head portion and a shed, a metal cap cemented to the top of the head portion, and a metal pin cemented to the lower end of the head portion at a pin hole formed in the head portion. The pin hole has a closed top and a downward opening, and its inside surface includes a cylindrical surface portion around the opening, a curved top surface and a round corner surface forming a smooth boundary between the cylindrical surface portion and the curved top surface. The cemented part of the inside surface of the hole has sands rigidly deposited thereon over a range from its lower end to a level within .+-.3 mm of the junction between the cylindrical surface portion and the round corner surface. The cylindrical surface portion has a radius equal to D and the round corner surface has a radius of curvature equal to Y, such that a ratio of Y/D is in the range of 0.3-0.45.

Suspension insulator

The disclosed insulator has an insulating member with a cylindrical core, a metal cap with a central hole of inside diameter D so that the core of the member is cemented to the central hole of the metal cap, and a metal pin cemented to the inside of the core of the member. The metal pin has a cemented rod portion with a diameter d.sub.1 and a large-diameter portion with an outside diameter d.sub.2 at an end buried in the core of the member. The diameters satisfy the conditions of

An explosion-preventing suspension insulator includes an insulator body and a metal cap and a metal pin both being bonded to the insulator body by means of cement. A synthetic resin based electrical insulating film having a Young's modulus of elasticity of from 20,000 to 80,000 kgf/cm.sup.2 is provided in a specific thickness on the inner surface of the metal cap and the outer surface of the metal pin at a portion where the metal pin is buried into the cement. The preferred thickness of each electrical insulating film is from 600 to 1,500 .mu.m.

Explosion-preventing suspension insulator

A ball and socket type suspension insulator, wherein the radius of curvature at the fillet portion between the shank portion and a ball portion of a ball pin buried and secured into the inside of a head portion of an insulator body is designed at 30-40% of the diameter of the pin shank portion, and the angle which a contact surface between the socket portion of the cap attached to the outer surface of the head of the insulator body and the ball pin forms with respect to the horizontal plane is 38.degree.-45.degree..

Ball and socket type suspension insulator

The suspension insulator of the present invention has an improved shape of the embedding portion of a metal pin, which is an embedding multi-step portion constructed with an inverted spherical convex trapezoid upper expanded portion having a larger surface at the top end and an inverted frust-conical lower expanded portion succeeding to the upper expanded portion. By using such a metal pin, the stress distribution of the insulating body is made uniform and therefore a small size and light weight of suspension insulator having high tensile strength is obtained.

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Nagoya, Japan

Hiroshi Nozaki