US3264405A

US3264405A - Bendable base insulator

Info

Publication number: US3264405A
Application number: US412699A
Authority: US
Inventors: Carl D Fiero
Original assignee: Lapp Insulator Co LLC
Current assignee: LAPP ACQUISITION Corp A DE CORP; Lapp Insulator Co LLC
Priority date: 1964-11-20
Filing date: 1964-11-20
Publication date: 1966-08-02
Anticipated expiration: 1983-08-02

Description

Aug. 2, 1966 c. m. HERO BENDABLE BASE INSULATOR Filed Nov. 20, 1964 FIG 5 INVENTOR.

CARL D. FIERO ATTORNF'YS United States Patent York Filed Nov. 20, 1964, Ser. No. 412,699 Claims. (Cl. 174-158) The present invention relates to a bendable support or base for electric insulators and more particularly to a bendable support or base member adapted to be interposed between the ceramic body of an electric insulator and the pole, tower or other structure supporting the insulator, such member being arranged so as to be bendable laterally in the direction of the line conductor that is supported by the insulator. Such bending allows the insulator to cant in response to overload transverse stress placed upon the insulator by the conductor, for example, from a break in the conductor on one side of the insulator.

Previous station and line post insulators have been mounted rigidly relative to their supporting structures. They have ordinarily extended either vertically or generally horizontally from poles or towers so that stresses placed on them by the supported line conductor were transverse to the insulators and operated in cantilever. Also, power line insulators are preferably made of frangible ceramic material that is not highly resistant to transverse or cantilever stresses.

The stringing tension of the line conductor supported by line post insulators is frequently 5000 to 6000 pounds and often exceeds the cantilever strength of the insulators which support it, so that when the line breaks, the transverse stress from the tension of the unbroken spans suddenly appears on the insulators next to the break and is often sufficient to break them. Breakage of these insulators in turn lets the line conductor down and can place succeeding insulators under overload cantilever stress whereby the insulator breakage is cascaded down the line. Any such insulator breakage lets the line down and increases the danger, ditficulty, time, and expense of repair.

It is an object of this invention to prevent breakage of insulators in response to transverse stresses produced by conductor breakage.

Another object of the invention is to prevent cascading insulator breakage in response to a break in a line conductor.

Another object of the invention is to reduce the cost and complexity of repairing a broken line conductor.

Another object of the invention is to minimize the danger and damage from the breaking of a line conductor.

Another object of the invention is to make replaceable bendable bases that are adapted to relieve insulators of overload transverse stresses especially from a break in a power line. I

Another object of the invention is to make insulator bases that are relatively rigid vertically or in directions transverse to the line conductor supported by the insulator and that are bendable in the direction of the line conductor to relieve the insulators of overload transverse stresses resulting from a break in the line.

To these and other ends the invention resides in certain improvements and combinations, all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of this specification.

In the drawings:

FIG. 1 shows a plan view of a horizontally mounted line post insulator supporting a line conductor and having a bendable base according to the invention;

FIG. 2 shows a side elevation of the insulator of FIG. 1;

FIG. 3 shows a partial top view of the insulator of FIG. 1 with its base bent;

p 3,264,405 Patented August 2, 1966 ice FIG. 4 shows a plan view of a bendable base for an insulator according to the invention; and

FIG. 5 shows a side elevation of a standard line post insulator having a bendable base that is bent.

The drawings illustrate the invention as applied to standard line post insulators and horizontal mounting line post insulators. The invention can also be used with station posts, cap and pin insulators, and any insulator that is rigidly mounted so as to be subjected to transverse or cantilever stresses. FIGS. 1-3 show a horizontal mounting line post insulator 10 arranged on a supporting structure 11 such as a conventional pole or tower. A conductor 13 is supported at the outer end of insulator 10 in a conventional manner.

A bendable material such as steel preferably in the form of web 14 is arranged between the ceramic body of the insulator 10 and the support structure 11. Web 14 is oriented transversely of conductor 13 so as to give relatively rigid vertical support to insulator 10 and conductor 13 and to be bendable only laterally of support structure 11 and longitudinally of conductor 13.

Bendable web 14 is preferably cast, welded, or otherwise forrned integrally with plates 16 and 17plate 16 being adapted for attachment to supporting structure 11, and plate 17 being either integral with base 15 of insulator 10 or adapted for attachment to base 15. As illustrated in FIGS. 13, plate 17 is bolted to base 15 of insulator 10, and plate 16 is bolted to support structure 11. When a bendable base including bendable web 14 is formed integrally with the insulator base 15, the entire base, including bendable web 14, is cemented to the ceramic body of insulator 10 in the usual fashion.

FIG. 3 illustrates bendable web 14 as bent in response to overload transverse stress placed upon insulator 10 by the line conductor. When a break in the line occurs on one side of insulator 10, insulator 10 is heavily stressed from the other side by both the tension and weight of the next unbroken span of conductor, and such stress tends to cant insulator 10. Bending of bendable web 14 allows insulator 10 to cant and introduces slack into the intact span of line, thus greatly reducing line tension between insulator upholding the intact span so as to reduce the transverse stress on insulator 10 produced by the break in the line.

Although canting of insulator 10 may shorten the distance spanned by the intact conductor by only a few inches, such efiFective shortening greatly reduces the tension in that span. It is preferred that insulator 10 is made strong enough to withstand the transverse stress remaining after it has canted to introduce tension-relieving sag in the intact span. Thus, bendable web 14 operates to limit the transverse stress on frangible, ceramic insulator 10 to values below those capable of breaking the insulator.

As best seen in FIG. 2, bendable web 14 has great strength and rigidity vertically of conductor 13 and can uphold insulator 10 against the weight of the conductor 13. Bendable web 14 is preferably made of a thickness and strength such that it will bend before the transverse stresses on insulator 10 exceed its breaking point. Also, the relative strength of insulator 10 and the yield strength of bendable web 14, are preferably selected relative to the transverse stress expected to be placed upon insulator 10 by a break in conductor 13 so that the bending of the bendable web 14 will cant insulator 10 to reduce line tension sufficiently so that insulator 10 will withstand the remaining transverse stress and not break. In turn, if insulator 10, because of bendable web 14, is able to withstand the stress of a line breakage without failing, cascading insulator breakage is avoided.

FIGS. 4 and 5 show a bendable web insulator base adapted for a standard line post insulator. This base has a pair of cooperating bendable web portions 20 arranged diametrically on opposite sides of a central aperture 21 in

plates

18 and 19. Aperture 21 is arranged for receiving a mounting stud by which insulator 22 is connected to pole 11 in the usual fashion. With such an arrangement, the mounting stud (not shown) bends along with bendable web portions 20. The illustrated bendable base including bendable webs 20 and

plates

18 and 19 is adapted for either connection to or integration with the base of an insulator, and although

plates

18 and 19 are illustrated as circular, they can be square, rectangular, or any other convenient shape.

In FIG. bendable web 20 is shown as bent in response to the transverse cantilever stress placed upon insulator 22 by the intact span of conductor 23. This bending allows insulator 22 to cant in the direction of the intact span of conductor 23, and this reduces the transverse stress on insulator 22 so as to prevent its breaking.

Bendable webs incorporated in insulator bases according to the invention not only relieve insulators of breakage and prevent cascading insulator breakage, but keep unbroken spans of line conductor aloft and secure to unbroken insulators and supporting structures so as to reduce the shock hazards and danger from line conductor breakage. This saving of insulators from breakage in response to line conductor breakage also simplifies repairs. In some instances it is possible to splice the broken line and leave the insulators with bent bases in place and operating. Bent-base insulators can then be replaced later at the convenience of the line crew. This speeds repairs to broken line conductors by eliminating the necessity for immediate replacement of broken insulators. Depending upon the construction of the insulator and the bendable web base portion, either the bendable base portion only, or the insulator having an integral bendable base can be replaced. Also, it is possible to repair bent insulator bases by bending them back to their original positions with or without disconnecting the line from the insulator.

While the invention has been disclosed herein by reference to the details of a preferred embodiment, it is to be understood that such disclosure is intended in an illustrative, rather than a limiting sense, and it is contemplated that various modifications of the construction and arrangement of the parts will readily occur to those skilled in the art, within the spirit of the invention and the scope of the appended claims.

I claim:

1. An insulator for attaching line conductor means which include a line conductor, to a support structure, said 5 insulator comprising: a dielectric body having a distal end and a proximal end; holding means at said distal end for holding said line conductor means with the longitudinal axis of said conductor when in position being coincident at said holding means with a straight reference line; base means at said proximal end, which comprise inelastic web means that support said body and that are unyieldingly rigid relative to stress components at least up to the weight of said body and line conductor means including said line conductor, when applied to said web means transversely to said reference line, but bendingly yieldable to stress components sufficient to break said body when applied along said reference line to said distal end, whereby, when line conductor means including a line conductor are held by said insulator and stress components sufiicient to break said body are applied through said line conductor, said insulator is canted to relieve at least a portion of said stress component.

2. An insulator according to claim 1, wherein said web means comprise a single, inelastic web, the dimension of which transverse to said line and to its dimension from the body end of the web to the support structure end of the web is substantially greater than its dimension generally parallel to said line.

3. An insulator according to claim 1, wherein said web means comprise a plurality of inelastic Webs, the dimensions of which transverse to said line and to their dimensions from the body end of the web to the support structure end of the web are substantially greater than their dimensions generally parallel to said line.

4. An insulator according to claim 1, wherein said web means are steel.

5. An insulator according to claim 1, wherein said base means includes means for securing said body to said web means and means for fastening said web means to said support structure.

References Cited by the Examiner OTHER REFERENCES Electrical World, vol. 156, No. 19, Nov. 8 and 9.

LARAMIE E. ASKIN, Primary Examiner.

Claims

1. AN INSULATOR FOR ATTACHING LINE CONDUCTOR MEANS WHICH INCLUDE A LINE CONDUCTOR, TO A SUPPORT STRUCTURE, SAID INSULATOR COMPRISING: A DIELECTRIC BODY HAVING A DISTAL END AND A PROXIMAL END; HOLDING MEANS AT SAID DISTAL END FOR HOLDING SAID LINE CONDUCTOR MEANS WITH THE LONGITUDINAL AXIS OF SAID CONDUCTOR WHEN IN POSITION BEING COINCIDENT AT SAID HOLDING MEANS WITH A STRAIGHT REFERENCE LINE; BASE MEANS AT SAID PROXIMAL END, WHICH COMPRISES INELASTIC WEB MEANS THAT SUPPORT SAID BODY AND THAT ARE UNYIELDINGLY RIGID RELATIVE TO STRESS COMPONENTS AT LEAST UP TO THE WEIGHT OF SAID BODY AND LINE CONDUCTOR MEANS INCLUDING SAID LINE CONDUCTOR, WHEN APPLIED TO SAID WEB MEANS TRANSVERSELY TO SAID REFERENCE LINE, BUT BENDINGLY YIELDABLE TO STRESS COMPONENTS SUFFICIENT TO BREAK SAID BODY WHEN APPLIED ALONG SAID REFERENCE LINE TO SAID DISTAL END, WHEREBY, WHEN LINE CONDUCTOR MEANS INCLUDING A LINE CONDUCTOR ARE HELD BY SAID INSULATOR AND STRESS COMPONENTS SUFFICIENT TO BREAK SAID BODY ARE APPLIED THROUGH SAID LINE CONDUCTOR, SAID INSULATOR IS CANTED TO RELIEVE AT LEAST A PORTION OF SAID STRESS COMPONENT.