US3110760A

US3110760A - Insulators with helical fin and tapered body

Info

Publication number: US3110760A
Application number: US124406A
Authority: US
Inventors: Jean M Mousson
Original assignee: Compagnie General dElectro Ceramique SA
Current assignee: Compagnie General dElectro Ceramique SA
Priority date: 1960-07-19
Filing date: 1961-07-17
Publication date: 1963-11-12
Anticipated expiration: 1980-11-12

Description

Nov; 12, 1963 J. M. moussou INSULATORS win! HELICAL FIN AND TAPERED BODY Filed July 1'7, 1961 Fig, 1 PRIOR ART United States Patent Ofi ice Claims priority, application France July 19, 196i 3 Claims. (Ql. 174211) 4 The present invention relates to an improvement in insulators with helicoidal fins for high-tension lines or apparatus, with a view to improving the operating characteristics of insulators during rain, especially in the case of a. polluted atmosphere. It consists in constructing the insulator in such manner that the edge of at least one of the spirals constituting the helicoidal fin passes beyond the edge of the lower adjacent spiral.

The construction and the scope of the invention will be better understood by reference to the accompanying drawings, in which:

FIG. 1 represents a view in profile and partly IIICIOSS- section of an insulator with a heli-coidal fin of known type tion in profile and partly in cross-section.

The insulator of FIG. 1 comprises essentially a barrel body .1 of insulating material, ceramic for example, on which is wound a helicoidal fin 2 defined by spirals 3. Two metal fittings 4 are sealed into the interior of the body 1. The section through a diametral plane of this insulator, shown at the left-hand side of FIG. .1, shows the profile of the spiral, characterized in the present example by two double bosses 5, 6' and 7, 8. Thus, two helicoidal channels are formed which collect and conduct away the rain water, ensuring an eifective washing of this portion ofthe fin. It has however been found that for a certain inclination of the insulator with respect to the profile of the fin, the collected water may overflow and drip on to the spiral below instead of running down the channels. When the spirals are suificiently close together, they may thus be short-circuited, which may give rise to a flash-over.

It is of cotu'se possible to increase the pitch of the helicoidal fin by spacing the spirals further apart, but the line of leakage is thereby diminished and the protection of the body against power arcs resulting from the presence of close spirals is reduced.

In accordance with'one form of the invention, it is possible to arrange two or more helicoidal fins in such manner that at least one has a length of spiral section less than that of the other or others. In this way, approximately the same line of leakage is maintained, measured along a generator line, while removing a certain number of successive spirals ttrom the danger of short-circuit by streams of water. On the other hand, the line of leakage measured along the development of the helix is reduced by 1/ 2, 1/3 or 1/ n, depending on the number of helixes adopted, and since these diiferent helixes are parallel, the insulation along the helix has its value divided byd, 9 or 11 g This solution is acceptable in certain cases, when the effects of pollution are limited, but it can no longer be FIGS. 2, 3 and 4 show different forms of the invenspiral extends beyond the edge or" the spiral below.' Account is talren of the reduction in diameter of the body towards the bottom by providing a metal fitting 12 sealed internally in the upper portion and a metal fitting 13 sealed externally in the lower portion.

According to the embodiment shown in FIG. 3, the body of the insulator 20 is not trusto-conical as in FIG. 2, but has a diameter which decreases and increases periodically from the upper portion of the insulator to the lower portion. A helix 21 is wound on this body. Although in the construction described, the diameter of the body varies in a periodic and uniform manner along the axis of the insulator, it is clear that this condition is not necessary, and that other laws of variation may be chosen. In any event, it will be auadvantage that the extremities of the body in which the metal fittings 22 are sealed, are located in a zone of maximum diameter.

In accordance with the embodiment shown in FIG. 4, the body of the insulator 31) is cylindrical, but the length of the profile of the spiral of the helicoidal fin 31 varies periodically between two limits along the longitudinal axis, in order to avoid successive spirals from having the same length of profile along any particular generator line. It is essential that the period of variation of the length of profile of the spiral should not correspond to a pitch or a whole multiple of a pitch of the helix.

The fabrication of the insulators in accordance with FIG. 2, 3 or 4, does not present any difficulty. In the the period desired.

case of FIGS. 2 and 3, it is only necessary to give the tool which cuts the helix in the blank, a radial movement, the law or" which is combined in a simple manner with the axial movement.

In the case of the einbodiment'raccordin-g to FIG. 4,

it is sufficient to arrange, after a first tool which has cut a regular helix, a second tool given a radial movement combined with the axial movement in accordance with In this case, naturally, the profile of the spiral should be such that the shortening of the length does not interfere with the collection and the flowgang-away of the water through the helicoidal channels t is quite clear that the constructions described are only given by way of example and without any limitation, certain details of some being even applicable to the others, while remaining Within the scope of the invention.

What I claim is:

l. A solid core suspension insulator comprising an insulator body whose diameter varies along the axis of the insulator, said body being provided with at least one peripheral spiral flange disposed extending axially on said body from one end to the other thereof, such that the radial depth of said flange is constant throughout its entire length and said body having a metal fitting sealed at each end thereof, at least one of said fittings being internally sealed.

2. A solid core suspension insulator comprising an elongated frustro-conical insulator body, said body being provided with at least one peripheral spiral flange disposed extending axially on said body irom one end to the other thereof such that the radial depth of said flange is constant throughout its entire length, a first metal fitting sealed internally in the uppermost portion of said body and a second metal fitting sealed externally on the lowermost portion or" said body.

3. A solid core suspension insulator comprising an elongated insulator body who-se diameter varies in a periodic manner along the axis of the insulator, said body being provided with at least one peripheral spiral flange disposed extending axially on said body from one end to the other thereof, such that the radial depth of said flange is conmy 3? V stant thmughsut its entire length, a first metal fitting 1,942,284 stza-lvscl internally at one end of said bsdy and a second 2,175,336 metal fitting sealed internally at the: :othsr end of said body.

t 5 391,017 References Cited in the file of this patent 349,410 Q" )1 UNITED STATES PATENTS fi; 1,811,530 Baum June 23, 1931 845:498 1,870,141 Regerbis et a1 Aug. 2, 1932 Halton Jan. 2, 1934 Austin Oct. 10, 1939 FOREIGN :fPAT EN TS Germany M21124, 1924 Italy June 15, 1937 France 2 Apr. 27, 1959 France Jan. 22, 19 4-2 Great Britain Aug. 24, 1960

Claims

1. A SOLID CORE SUSPENSION INSULATOR COMPRISING AN INSULATOR BODY WHOSE DIAMETER VARIES ALONG THE AXIS OF THE INSULATOR, SAID BODY BEING PROVIDED WITH AT LEAST ONE PERIPHERAL SPIRAL FLANGE DISPOSED EXTENDING AXIALLY ON SAID BODY FROM ONE END TO THE OTHER THEREOF, SUCH THAT THE RADIAL DEPTH OF SAID FLANGE IS CONSTANT THROUGHOUT ITS ENTIRE LENGTH AND SAID BODY HAVING A METAL FITTING SEALED AT EACH END THEREOF, AT LEAST ONE OF SAID FITTINGS BEING INTERNALLY SEALED.