US2239809A - Insulator - Google Patents

Description

April 29, 1941. w. H. BURLESON INSULATQR Filed March 9, 1939 CONDUCT/V5 COAT/Ive 3nventor fla 4. Mm; H. B weLEsoN attorney Patented Apr. 29, 1941 INSULATOR Wade H. Burleson, Mansfield, Ohio, assignor to The Ohio Brass Company, Mansfield, Ohio, a, corporation of New Jersey Application March 9, 1939, Serial No. 260,722

2 Claims.

My invention relates to insulators for use in connection with high-voltage lines of transmission and applies particularly to those insulators employing caps, pins and conductor clamps of metal as in the case of insulators of the suspension, post, pillar and pin types.

One object of my invention is to provide an insulator having radio control, as for instance by a conductive coating upon the surface of the insulator whereby radio interference is reduced or prevented.

Another object of my invention is to provide a connection between the caps, conductor holders, pin supports, etc. and the coating for reducing or preventing radio interference whereby the corona or discharge between the cap and conductive coating is prevented.

A still further object of my invention is to provide a simple, economical, durable and efficient means of making a connection between the metal cap, pin, conductor holder, etc. and the conductive coating.

My invention resides in the new, novel and useful construction, combination and relation of the parts hereinafter described and disclosed in the drawing accompanying this specification.

In the drawing:

Fig. 1 is a side view in partial section of a suspension type insulator provided with cap and pin and including my contribution to the art.

Fig. 2 shows a helically wound spring ring disclosed in Fig. 1 for electrically connecting the cap and pin to the adjacent conductive coating.

Fig. 3 is a modified form of connector which consists of a fluted ring of solid spring material.

Fig. 4 is another form of connector consisting of a plain ring of solid material.

Fig. 5 shows a rectangular cross section of solid material which may be used in constructing the rings shown in Figs. 3 and 4.

Fig. 6 shows a partial section of an insulator body and cap in which the cap and conductive coating is connected by a spring ring of cross section approaching that of the space between the cap and conductive coating.

The insulators in question consist of a body of vitreous insulating materials such as porcelain, glass, etc., with a coating of a silicate glaze fired to the body as composition materials such as a mixture of synthetic resins and fillers is not suitable for high-voltage purposes. The insulator is often provided with a metal cap or conductor holder and/or pin to support the insulator and insulators of such construction are very likely to produce corona or discharge from some part of the metal fitting. 1

It is well known that an insulator of-thev construction just described is very apt to set up high frequency oscillations which affect near by radio apparatus and that this corona or discharge may be materially controlled by placing a conductive coating upon the surface of the insulator adjacent to the metal cap, clamp or pin and electrically connecting the adjacent metal fitting to the conductive coating whereby discharge between the fitting and coating is eliminated and any discharge from the free edge of the conductive coating will be so reduced per unit length or area of the coating that the effect upon radio apparatus is zero or practically nil.

Such coatings as I refer to are disclosed in Austin 1,735,829 and Lusignan 1,994,281 in which a coating of metal is employed but it has been found that the discharge may be controlledby a coating produced by other means, as for instance, a high resistance or low-conductivity coating of a metallic compound such as iron oxide or copper oxide applied as a fired glaze to a portion of the surface of the dielectric either in place of or over a portion of the silica glaze adjacent the metal fittings. If desired the coating may be graded as to conductivity in which the specific conductivity per unit area decreases away from fitting by varying the composition of the glaze or as disclosed by Austin supra.

In Fig. l I show a suspension type of insulator comprising a dielectric body I preferably of porcelain with a metal cap 2 secured thereto as by means of cement 3 and having a socket 4 whereby the cap may be attached to the pin of a like insulator from which it is suspended.

The insulator is also provided with a metallic pin 5 secured to the dielectric body I by means of cement 6.

The dielectric body I is provided with conductive coatings I and 8 which may be of metal applied as in the case of Austin or Lusignan supra or a coating of a metallic compound in the form of a fired glaze. I have shown the conductive coatings I and 8 as extending along the surface of the dielectric body parallel to the cap 2 and pin 5 respectively, as this overlapping also tends to reduce somewhat the concentration per unit area of the corona discharge between the metal fittings and the conductive coatings, even though there is no direct electrical connection between the fittings and conductive coatings.

As before stated the metal fitting and control coating should be in direct contact or electrically connected but as it is practically impossible to be assured that the metal fittings will make contact with the conductive coatings, I

provide means for securing equivalent results by making an electrical connection between the parts and which means is simple, inexpensive, eflicient and applicable to the insulator after it has been assembled and before shipping or it may be applied to insulators already in the field and lacking the proper connection between the fittings and the conductive coatings.

My preferred means comprises a helically wound spring ring as shown in Fig. 2 and which may be formed of spring steel wire preferably with a protective coating such as cadmium or zinc to prevent corrosion or the ring may be formed of non-corroding metal such as Nichrome, Monel or phosphor bronze. Wire, of one of these metals, is wound upon a mandrel of proper size and of any length with the convolution contacting and then cut to lengths which, when the free ends are united as by welding or interlinking will produce a yieldable ring and of such diameter which will require some stretching in order to place it in position on the insulator as shown at 9 in Fig. 1 and which when released will seat itself firmly in the space between the cap and the conductive coating with the individual convolution in contact with each.

This form of connection is easily applied and 3 is constantly exerting pressure against the parts to be connected as the ring is under tension since the normal diameter of the ring is less than that of the space in which the ring is to seat and being of permanent metal will preserve connection between the parts as long as the insulator is in service. The helically wound spring ring may be made with its convolution of any diameter required and the diameter of the ring itself may be such as to exert practically any desired tension upon the parts to meet conditions and the ring will adjust itself to Various shapes other than circular.

At ill I have shown the helically wound spring ring as connecting the pin 5 and the conductive coating 8 and the ring rests in a groove H and is of such size that it is necessary to compress the same in applying it to the insulator in assembly thus the tendency will be for the ring to expand in the assembled insulator but still contact with the pin and will form a permanent connection between the pin 5 and the coating 8.

In Fig. 3 l. have shown another form of spring ring which is made of solid round wire and split at some point, as for instance, at I2. The diameter of the material may be such as required to meet conditions as well as the normal diameter of the ring itself. In this case the ring will contact with the parts to be connected at such points as I! but such contact will be very firm and secure depending upon the material of which the ring is composed and the normal diameter thereof which is less than that required to properly meet requirements.

In Fig. 4 I have shown a simple split spring ring formed of round material which may be of any diameter required.

In Fig. 5 I have shown a rectangular cross section which may be substituted for the material of which the rings in Figs. 13 and 4 are composed.

In Fig. 6 the section II of the spring ring is shown as of triangular cross section and which may be used in constructing rings shown either in Figs. 3 and 4. The triangular cross section has the tendency to fit into and form a more eflicient contact under some conditions with the parts to be connected than material of some other section.

Attempts have been made in the past to form a connection between the metal fittings and a conducting coating, but such means as proposed did not provide a means for maintaining an automatically adjustable connection between the parts, with the result that changing conditions would open up such contact as originally existed, thus destroying the beneficial results.

While I have illustrated and described in detail a suspension type of insulator, my invention includes other types, such as pillar, Post and line insulators.

The surface l5 of the insulator body may be coated with the usual silica glaze and applied, as well as coatings I and 8, at .the time of firing the body.

Having described my invention, I wish to be limited only by my claims.

I claim:

1. An insulator comprising a dielectric member and a metal fitting secured thereto, said member and fitting having relatively converging faces forming a peripheral groove about said insulator and means for providing good electrical connection between said fitting and the surface of said dielectric member, said means comprising a conducting coating on the surface of said dielectric member within said groove and a longitudinally and transversely resilient band disposed in said groove about said insulator and drawn inwardly into said groove by the resiliency of said band into close engagement with the converging faces of said groove, said band being formed of an elongated strand of resilient conducting material having recurrent peripherally spaced inwardly bent portions for engaging said converging faces, the resiliency of said band and the spacing of the points of contact thereof with said converging faces insuring good electrical connection at each point of contact to minimize radio disturbances due to electrical discharges.

2. An insulator comprising a dielectric member and a metal fitting secured thereto, said member and fitting having relatively converging faces forming a peripheral groove about said insulator and means for making good electrical connection between said fitting and the surface of said dielectric member, said means comprising a conducting coating on the surface of said dielectric member within said groove and a longitudinally and transversely resilient band disposed in said groove about said insulator and drawn inwardly into said groove by the resiliency of said band into close engagement with the converging faces of said groove, said band being formed of an elongated strand of resilient conducting material wound in helix to provide recurrent peripherally spaced inwardly bent portions for engaging said converging faces insuring good electrical connection at each point of contact to minimize radio disturbance due to electrical discharges.

WADE H. BURLESON.

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