Electricity: conductors and insulators – Insulators – Combined
Patent
1995-11-22
1998-08-18
Kincaid, Kristine L.
Electricity: conductors and insulators
Insulators
Combined
174137A, H01B 1748
Patent
active
057960488
DESCRIPTION:
BRIEF SUMMARY
APPLICABLE FIELD
The present invention relates to insulators with conductive coatings to be used for supporting wires or in interrupting devices. More specifically, the invention relates to insulators conductive coatings in which a metal fitting is joined to an insulator body with a cement material having high electric resistance, such as Portland cement. The insulator body has an electrically conductive coating that is electrically connected to the metal fitting.
BACKGROUND TECHNIQUE
When corona discharge occurs due to a stained surface of an insulator or the like, surrounding radios or televisions suffer noise troubles. In order to prevent such a phenomenon, insulators with conductive coatings. To the surface of the insulator, which is made of porcelain, is applied a glaze having conductivity (hereinafter referred to as conductive glaze), and a conductive means is provided between the metal fitting and the conductive glaze layer so that a given amount of electric current may flow between the metal fitting and the conductive glaze layer. In order to secure this electrical contact various constructions have been proposed up to now. In the following, an example of such a conductive means employed at a base portion of a station post insulator (a rod-shaped insulator) will be explained.
For example, a prior art structure as shown in FIG. 11 is known in which an insulator body and a metal fitting are electrically connected to each other by using a metal spraying method. More specifically, a conductive glaze layer 31 is formed on the outer peripheral surface of the porcelain body 30, and the metal fitting 33 is fixed to an end of the porcelain body 30 via the conductive glaze layer 31 and a cement material 32. A conductive metal 34 is sprayed onto the surfaces of the conductive glaze layer 31, an end of the cement material 32 and the metal fitting 33 so that the conductive glaze layer 31 and the metal fitting 33 may be electrically connected. In the figure, reference numerals 35 and 36 denote insulating sand and an insulating film, respectively.
Further, a prior art structure as shown in FIG. 12 is known as an example using a metal-connecting method. More specifically, a conductive paint 38 is applied onto an end face of a porcelain body 30 and a conductive glaze layer 31 provided with a sand portion, and the conductive paint 38 and the metal fitting 33 are electrically connected to each other by connecting them with a conductive metal 39. In this case, a coil spring is used as the conductive metal 39.
Furthermore, although not shown, a structure is known that is formed by a conductive cementing method in which a conductive material such as carbon is mixed into a cement material between a porcelain body and a metal fitting so as to ensure electrical connection between the porcelain body and the metal fitting.
However, in the metal spraying process shown in FIG. 11, a Metallikon material (94 wt % Pb, 5 wt % Sb, and 1 wt % remainder) is ordinarily employed as the conductive metal 34. Accordingly, it is feared that a worker may suffer from a disease caused by lead (Pb) due to handling the Metallikon material during the production of insulators. Further, in order to prevent corrosion of the surface of metal 34 through exposure to air, a corrosion-preventing film 40 is applied after spraying the metal. As mentioned above, there are additional steps of spraying the conductive metal 34 and applying the corrosive-preventing film 40 in the producing process, which raises the production cost together with costs of the conductive metallic material such as the Metallikon material and the corrosion-preventing film.
In the metal connecting method shown in FIG. 12, the metal 39 is likely to be corroded with moisture possessed by the cement material 32, and there is a high possibility that conductivity is reduced due to the corrosion. As shown in FIG. 12, a sponge 41 is arranged to absorb the moisture from the cement 32, and a conductive paint 38 is applied to the surfaces of the porcelain 30 and the conductive glaze layer
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Kutsuna Eiji
Mori Shigeo
Nozaki Hiroshi
Suzuki Yoshihiro
Cuneo Kamand
Kincaid Kristine L.
NGK Insulators Ltd.
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