US3547386A - Hinged suspension clamp - Google Patents

Description

United States Patent inventors Thomas J. Burgess Toronto; Gordon J. Clarke, Bramalea, Ontario, Canada Appl. No 809,703 Filed Mar. 24, 1969 Patented Dec. 15, 1970 Assignee Lacal industries Limited Ontario, Canada lilNGED SUSPENSION CLAMP 2 Claims, 3 Drawing Figs.

U.S. Cl 248/63; 174/40, 174/ 144, 248/74 Int. Cl F161 3/08, H02g 7/00, H01 b 17/00 Field of Search 248/62, 63,

[56] References Cited UNITED STATES PATENTS 2,596,022 5/1952 Genter 248/63X 3,155,354 10/1964 Lindsey... 248/63 3,383,459 5/1968 Short 248/63 Primary Examiner-Chancellor E. Harris Attorney-Fetherstonhaugh & Co.

ABSTRACT: The invention is a suspension clamp for an electric cable that consists of a pair of cooperating jaws formed with seats to accommodate a cable and having a clamp to hold them in a closed position. The clamp is suspended by means of a mounting hole formed in one of the jaws that is generally below the upper contour of the clamp. The other jaw is formed with an opening to render the mounting hole accessible. The clamp is able to mount the cable in close proximity to a line insulator and its edges are smoothed and rounded to reduce corona in use.

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HINGED SUSPENSION CLAMP This invention relates to a suspension clamp for an electric cable of the type used in high voltage transmission of electricity.

The design requirements of clamps of this type are numerous and in practice the most common designs that have been used commonly over the years have been the result of a compromise between apparently conflicting design requirements. One of the requirements is that the clamp should not present sharp edges so that the corona loss will not be unduly high. There has thus been a tendency towards clamps having a cast construction, the elements of which are fairly thick and the edges of which can be conveniently rounded to avoid sharp edges that result in corona loss to meet this design requirement. These clamps have been two-piece clamps and the clamping action has been due to bolt action on one side only of the cable. The mechanical clamping advantage has been relatively poor as compared with a clamping arrangement wherein the jaws are retained on both sides of the cable. The clamp is also relatively cumbersome and requires a long mounting time. Hinged clamping arrangements wherein cable is retained between two clamping jaws by means of a bolt clamping action on the opposite side of the cable to the hinge have never been adapted to the cast or forged construction without which they would be subject to the objection that they present too many sharp edges with unacceptable corona loss.

This invention relates to a cast or forged suspension clamp designed with rounded surfaces to minimize corona loss and having a hinged construction wherein the clamping arrangement is very much more efficient than the clamping arrangement of the existing cast suspension clamps. The improved clamping arrangement has been achieved without any sacrifice of corona reducing ability. The clamp of this invention is also a very substantial time saver in use. The time required to mount a cable in the clamp of this invention is about 2 minutes, as compared with about minutes for the presently popular two-piece cast clamp. The clamp also has a novel clamping arrangement that permits a close coupling of the clamp to a line insulator in use whereby to achieve better shielding and an improved voltage distribution across the individual insulators of an insulator string.

Generally speaking, a suspension clamp for electric cable according to this invention comprises a first jaw and a second jaw hinged to the first jaw by a hinge means. Clamping means spaced from the hinge means are manipulatable to clamp the jaws in a closed position. Each of the jaws is formed with a cable seat between the hinge means and the clamping means, the cable seat of each jaw being adapted to cooperate with the cable seat of the other jaw to embrace and retain a cable when the jaws are in a closed position. The first jaw is formed with mounting means for suspending the clamp. The clamping means preferably includes two clamping elements, one located on each side of the mounting means, and the jaws are made of cast metal and present rounded edges when in a closed position to reduce corona loss. The invention will be clearly understood after reading the following detailed specification read in conjunction with the drawings.

FIG. 1 is a side view of a cable clamp according to the invention with a standard connecting pin;

FIG. 2 shows the clamp of FIG. 1 from the end; and,

FIG. 3 is a perspective view of the clamp in the open positron.

In the drawings, the numeral 10 generally refers to a cable clamp according to this invention. It comprises a first jaw 12 and a second jaw 14, each made from a cast metal, such as aluminum or the like, and each being of substantial proportions with rounded edges, as illustrated, to reduce corona loss in use. The rounding of the edges of cast components in electric transmission to reduce corona loss is a well known and desirable expedient.

it will be noted that the two jaws 12 and 14 are hingedly connected together along their lower edge by means of a high tensile strength steel pin 16. I

The first jaw 12 is formed with a mounting plate 18 having a hole therethrough adapted to receive the pin of a standard connecting link 20. It will be noted that the mounting means is generally below the upper contour of the clamp when the jaws are closed, and that the second jaw 14 is formed with a depression 22 to accommodate the mounting means when the jaws are in a closed position. This location of the mounting plate 18 permits a close coupling of the clamp to the line insulator in use and achieves good shielding characteristics. The jaws are retained in a closed position by means of similar bolt assemblies 24 and 26 which cooperate with nuts 27. In each case, the nuts of the assembly are maintained in a recess in jaw 12 by means of a press fit. It will be apparent that by tightening the bolts 24 and 26 with respect to their respective nuts that the clamping arrangement of the jaws will be tightened on a cable that is located in the opposed and cooperating cable seats 30 and 31 of the jaws 12 and 14, respectively.

When it is desired to remove the cable from the clamp the bolts 24 and 26 are loosened from their respective nuts until the bolts are free of their nuts. This permits jaw 14 to swing downwardly through from the dotted line position of F IG. 2 to the solid line position, at which point the lip 34 thereof locks with the other jaw. The cable can then be removed from the clamp. Numeral 36 refers to a neoprene washer which is adapted to prevent the bolts from falling out of the section 14 as the clamp is opened. Numeral 38 refers to steel washers against which the clamp bolts are tightened when the clamp is closed.

In use, the clamp is suspended by means of the suspension pin 20 from the lower insulator of a string of insulators in an electricity transmitting system. The clamp is actuated to an open position and a cable is placed in the area of the cable seat 30. The open jaw is then closed so that the cable is clamped between the cooperating clamp seats 30 and 31 to securely mount the cable. It is possible to take a cable in and out of the clamp while the line is in service.

The hinged clamp with captive nuts 27 renders installation on live lines (using live line tools) much easier than is the case with a multipiece clamp design having separate clamping members. One tool holder is all that is required to slip the hinged clamp into position whereupon the hinged section 14 can be closed over the conductor and the bolts 26 tightened by means of a live line socket wrench. This is a one man operatron.

The clamp described is made of cast aluminum but it will be apparent that the essential rounded form could be achieved with a forged manufacture.

It will be apparent that the mechanical advantage of the hinged construction is very superior to one wherein the clamping arrangement is achieved by means of the equivalent of only the bolts 24 and 26. At the same time, there has been no loss in corona reducing characteristics because the incorporation of the hinged construction has not involved any new sharp edges. The suspension means 18 is low to the body of the clamp which will permit a close coupling of the unit to the lowermost insulator, a desirable feature from electrical conducting point of view.

We claim:

1. A suspension clamp for an electric cable comprising a first jaw, a second jaw hinged to said first jaw, hinge means hingedly connecting said first jaw to said second jaw, clamping means spaced from said jaw to said second jaw, clamping means spaced from said hinge means manipulatable to clamp said jaws in a closed position, each of said jaws being formed with a cable seat between said hinge means and said clamping means, the cable seat of each jaw being adapted to cooperate with the cable seat of the other jaw to embrace and retain a cable when said jaws are in a closed position, said first jaw being formed with mounting means for suspending said clamp, said jaws being of cast or forged metal and presenting rounded edges when in a close position whereby to reduce loss in use, said mounting means being generally below the upper contour of said clamp when said jaws are closed, said second jaw being formed with a depression.

2. A suspension clamp as claimed in claim 1 in which said clamping means includes two clamping elements, one located on each side of said mounting means on its upper edge to accommodate said mounting means when said jaws are closed.

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