JPH0155726B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to improvements in electrolytic corrosion-resistant insulators used in DC transmission lines and the like.

(Prior art) Conventionally, in DC transmission lines, in order to prevent electrolytic corrosion of pin fittings due to leakage current and destruction of the insulator due to this, the boundary between the pin fittings and the cement, where the leakage current density is highest, is An electrolytic corrosion-resistant insulator with galvanic anodes protruding from its outer periphery is used. (For example, Japanese Patent Publication No. 40-3054) (Problem to be solved by the invention) However, in a severely contaminated environment, the entire cement in which the pin fittings are buried becomes wet, and only the surface of the cement becomes partially wet due to the influence of wind, etc. When the insulator is dry, the electrical resistance between the insulator body and the pin metal fitting is the minimum value, which is the difference between the resistance value of the current anode part and the resistance value of the pin metal body buried in cement, and the leakage current is Problems remain in that not only does the metal flow into the metal pin, causing electrolytic corrosion, but also the rust generated by the electrolytic corrosion generates a large internal pressure stress inside the insulator, causing the insulator to break.

(Means for Solving the Problems) The present invention relates to an electrolytic corrosion-resistant insulator that solves these problems and does not cause electrolytic corrosion even under the above-mentioned special conditions. In an insulator which is filled and fixed with a pin fitting embedded in the insulator with its upper part, a galvanic anode, which is partially embedded in cement, is formed in the intermediate part of the pin fitting and is formed on the circumferential surface of the insulator. This is characterized in that the thin end portion of the insulator is located close to the inner surface of the insulator body.

(Example) Next, the present invention will be described in detail with reference to the illustrated example.

In the first embodiment shown in FIGS. 1 and 2,
1 is a porcelain insulator body; 2 is a pin fitting, such as a ball pin or clevis pin, which is fixed by embedding the upper part following the upper bulge in the cement 3 filled in the insulator body 1; 4 is a pin fitting of the insulator body 1; It is a socket cap that is placed on the head, and 2' is a bulging end at the lower end of the pin fitting 2. A galvanic anode 6, which is partially embedded in the cement 3, is formed in the middle of the pin fitting 2, and a galvanic anode 6 is formed on the circumferential surface of the galvanic anode 6 near the surface of the cement 3, where the leakage current density is maximum. The insulator body 1
A thin end portion 5 is formed close to the inner surface of.
Note that the galvanic anode 6 is formed integrally with the pin fitting body by a joining method such as casting or brazing, and the thin end portion 5 of the galvanic anode 6 is in contact with the inner surface of the insulator body 1. However, it is preferable to have a width of about 1 to 2.5 mm in consideration of manufacturing dimensional errors.Furthermore, this thin end portion 5 should have a thickness of about 1 to 5 mm. In addition, it is preferable to chamfer the cross section into an arc shape to prevent stress concentration and more reliably prevent the insulator body 1 from breaking. Next, the second embodiment shown in FIG. 3 is basically the same as the first embodiment described above, but in the second embodiment,
The galvanic anode 6 has an annular groove formed on its circumferential surface, and a thin end portion 5 having a wall thickness of about 1 to 5 mm is formed on the lower side of the anode 6, and a thin end portion 5 having a wall thickness of about 1 to 5 mm is formed in the annular groove, and a portion protruding from the thin end portion 5 is formed in the annular groove. An elastic O-ring 7 is fitted tightly onto the inner surface of the insulator body 1, and the thin end portion 5 is brought close to the inner surface of the insulator body 1. Further, the galvanic anode 6 is provided with a cement extraction hole 8 in the vertical direction. This elastic O-ring 7 securely holds the pin fitting 2 at the center of the insulator body 1 during cement filling, and also prevents leakage current flowing along the inner surface of the insulator body 1, thereby providing an even better performance. This embodiment differs from the first embodiment in that it exhibits an electrolytic corrosion prevention effect. The reason why leakage current can be blocked by the elastic O-ring 7 is that when the elastic O-ring 7 is made of a conductive material, the current always flows from the current anode 6 through the elastic O-ring 7 to the porcelain surface of the insulator body 1. This is because the potentials of the pin fitting 4 embedded in the cement 3, the galvanic anode 6, and the elastic O-ring 7 become the same and no potential difference occurs.On the other hand, when the elastic O-ring 7 is made of an insulating material, The current flows from the galvanic anode 6 through the surface of the elastic O-ring 7 to the porcelain surface of the insulator body 1, and the insulator body 1 is in contact with the pin fitting 4 embedded in the cement 3 and the elastic O-ring 7.
A potential difference is created between them, and a current tries to flow, but the resistance of the elastic O-ring 7 made of an insulating material is so large that the current is blocked at this part.
In either case, the leakage current can be blocked by the elastic O-ring 7, so that the pin fitting 4 embedded in the cement 3 and the galvanic anode 6 are not corroded. Further, the cement removal hole 8 is provided as necessary to facilitate assembly by discharging excess cement that has been prevented from flowing out by the elastic O-ring 7 to the outside.

(Function) The device configured as described above has a current bulge formed in the middle part of the pin fitting 2, such as a ball pin, whose upper part is embedded and fixed in the cement 3 filled in the insulator body 1. Since the thin end portion 5 of the anode 6 is close to the inner surface of the insulator body 1 and forms the least resistance portion, the entire cement 3 becomes wet as described above, and only the surface of the cement 3 becomes wet due to the influence of wind etc. Even under special conditions such as semi-dry conditions, leakage current always flows through the thin end portion 5 to the galvanic anode 6, and as a result, the galvanic anode 6 is subjected to electrolytic corrosion and at the same time the pin fitting 2 is exposed to electrochemical corrosion. This prevents electrical corrosion of the pin fittings 2. Furthermore, since the thin end portion 5 of the circumferential surface of the galvanic anode 6 is thin, even if rust occurs on the thin end portion 5 as a result of electrolytic corrosion due to leakage current, internal pressure stress is applied to the insulator body 1 due to this rust. becomes a very small value, and the insulator body 1
cannot be destroyed.

(Effects of the Invention) As is clear from the above description, the present invention allows the leakage current to always flow to the current anode by bringing the thin edge of the circumferential surface of the current anode close to the inner surface of the insulator body. This prevents electrolytic corrosion of the pin fittings, and by making the thin ends thinner, it alleviates the internal pressure stress inside the insulator body due to rust that occurs in the current anode, and prevents damage to the insulator body. This material contributes greatly to the development of industry as it solves the problems of conventional electrolytic corrosion resistant insulators used in other applications.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view showing a first embodiment of the present invention, Fig. 2 is a longitudinal sectional view of the main part thereof, and Fig. 3 is a longitudinal sectional view of the main part showing the second embodiment of the invention. It is a front view. 1: Insulator body, 2: Pin fittings, 3: Cement,
5: thin end, 6: galvanic anode.

Claims (1)

[Claims] 1 In an insulator in which an insulator body 1 is filled with cement 3 and a pin fitting 2 is embedded and fixed therein with its upper part, a galvanic anode is partially embedded in the cement 3 in the middle part of the pin fitting 2. An electrolytic corrosion-resistant insulator characterized in that a thin end portion 5 formed on the circumferential surface of the insulator body 1 is proximate to the inner surface of the insulator body 1.