US3196980A

US3196980A - Insulated personnel carrier

Info

Publication number: US3196980A
Application number: US148191A
Authority: US
Inventors: Harold L Rorden
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-10-27
Filing date: 1961-10-27
Publication date: 1965-07-27
Anticipated expiration: 1982-07-27

Description

July 27, 1965 H. L. RORDEN 3,196,980

cmmim July 27, 1965 H. RORDEN 3,196,980

INSULATED PERSONNEL CARRIER Filed Oct. 27, 1961 3 Sheets-Sheet 2 INVENTOR. HAzoLo L. 1202mm ATTORNEYS.

July 27, 1965 H. L. RORDEN 3,

INSULATED PERSONNEL CARRIER 5 Sheets-Sheet 3 Filed Oct. 2'7, 1961 IN VEN TOR. HAROLD L. Q0205! g WKJW ATTOENEYE.

United States Patent 3,196,980 INSULATED PERSONNEL CAR Harold L. Roi-den, 117 Whitford Ave., Nutley, NJ. Filed Get. 27, 1961, Ser. No. 148,191 Claims. (Cl. 182-46) This invention relates to the installation, maintenance and repair of electric line conductors and more generally to Working electrically energized conductors, conductor apparatus, and the like. The present application is a continuation in part of the application of Harold L. Rorden, Serial No. 105,456, filed April 25, 1961, now United States Patent 3,139,948.

Broadly, the invention relates to new and improved arrangements for working electrically energized conductors, providing for power line repair and maintenance, at high voltages, and under adverse conditions of wet weather and the like, while the line is electrically energized, simplifying and expediting the maintenance and repair of electric power lines and reducing or eliminating the use of insulated tools, as well as reducing the possibility of shock and other hazards incurred by workman in servicing and repairing electrically energized power lines and reducing service outages in electric supply systems.

The invention broadly considered is useful in Working on high tension lines at the highest voltages such as 338,000 volts, for example, but the embodiments of the invention to which the present application are primarily directed have for their object the provision of simplier and less expensive embodiments of the invention for use at lower voltages such as 25,000 volts or less, for example.

A further object of the invention is to provide ladders which may safely be employed by a workman in working upon high voltage energized power lines.

In the operation of electric power systems, continuity of service is an important consideration and interruptions due to line outages are undesirable and expensive. Accordingly, it is advantageous to conduct maintenance and repair operations without system shutdown and various methods and techniques for energized line working have been proposed, wherein the line conductors and conductor apparatus may be repaired or replaced without being disconnected from the associated energized circuits. One technique for energized line working which has been proposed involves the use of live-line tools, so-called, which facilitate manual manipulation of the conductors and related apparatus while the conductor is energized. However, because of the great amount of insulation required, such tools are cumbersome and unwieldy and even the simplier repair operations are difiicult and time consuming. Moreover, many repair operations in any event cannot readily be performed by the use of such tools and require that circuits be deenergized.

The present invention is concerned with a new concept of line working in which the lineman is maintained at the same potential as the energized conductor while performing maintenance and repair operations upon the conductor or related conductor apparatus. In contrast with the use of live-line tools just described, in which the lineman is electrically separated from the energized conductor by insulated tools, I have found that many advantages may be achieved by supporting a lineman adjacent the energized conductor in insulated relation to the earth'and energized to the same electrical potential as the conductor. This enables the lineman to make direct contact with the line conductor and permits manipulation of the conductor and conductor apparatus without use of insulating tools.

The present application is concerned with cases Where the weight of tools required or the physical height of the high voltage lines is not so high as to require hoists or motorized lifts for elevating the lineman to the lineto be worked upon and it would be physically practical to reach the line by single or extension ladders except for the high voltage involved. In accordance with the invention, I provide a ladder composed of light, strong electrically insulating material such as fiber reinforced plastic, for example, fiber-glass impregnated with insulating resin. However, that portion of the ladder upon which the workman will stand or be supported while he is Working upon the line is composed of or coated with conductive material, or is provided with a sheet-metal platform or other structure clamped to the rungs for supporting the workman, or otherwise secured to the ladder and a flexible conductor connected to the conductive support for the workman is provided which is adapted to be connected electrically to the line before the workman begins working upon it.

After this connection is made, the Workman is at the potential of the high voltage line and can contact the energized parts with bare hands or conventional work gloves. It will be understood that the electrical lines referred to herein as lower voltage contrasted with the very high tension lines referred to in the parent application, and which are physically low enough so that they can be reached by ladders, are nevertheless at voltages far in excess of those which may safely be applied to a workman in such a manner as to cause current topass through his body. However, the electric field effects are not so intense as at the higher voltages in excess of 25,000 volts and therefore a Faraday cage or electrostatic shield enclosing the workman is not required and the principal consideration is to cause the workman and his clothing to make contact with the electrically conducting portion of the ladder so that the workman is raised to the potential.

reference to the following detailed specification and claimsconsidered in conjunction with the accompanying drawings, in which: Y

FIG. 1 is a view in perspectiveof the upper end of a transmission line tower fragmentarily showing a portion of a transmission line upon which a Workman is required to work and illustrating the use of a ladder of such lightness that the workman may carry it with him in climbing the tower and may suspend it from the cross-arm;

FIG. 2 is a perspective view of another embodiment of the invention employing an extensible ladder which may if desired be mounted upon a vehicle .which provides the support therefor; and I FIG. 3 is a perspective view of another embodiment of the invention involving the use of a'ladder which is erected by the workman manually and rests at opposite ends against the high voltage line and the ground.

Like reference characters are utilized throughout the drawing to designate like'parts. V

For working upon transmission lines carried by towers such as a steel frame work tower 11 shown in FIG. 1 having the cross-arm structure comprising angle irons 12,

a ladder 13 is provided, having bracket means or

hooks

14 and 15 which are adapted to hook over the cross-arm or one of the angle irons 12 thereof. f The length Of the ladder 13 is greater than the distance 'between connections of the suspension insulator 16 by means of which a high tension conductor 17 is supported below the crossarm structure 12.

The lower portion of the ladder 13 is thus adjacent to the high tension conductor 17 in order to enable a workman standing at the lower end of the ladder to work upon the line 17. The ladder 13 is composed of structural material constituting an electrical insulator in order v.9 that the workman will be insulated from the ground potential existing upon the metallic tower 11 and cross-arm structure 12. However, the rungs at the lower end of the ladder 13 are covered by a sheet-metal frame work 19 or coated'with conductive material so that the rungs 18 have electrically conductive surfaces and the, adjacent hand holding portions of the ladder also have electrically conducting surfaces.

I The conducting metallic'frame work 19 to which the rungs 18 are electrically connected is connected also to a flexible cable 21'having an insulating sheath and having a clamp 22 electrically connected to the end thereof body when this connection is made and he can thereafter touch the line 17 or electrical fittings to be attached thereto-or adjusted thereon without causing any electrical current to pass through his body. 7

In order to steady the ladder 13 while a workman is working upon the high tension line 17, a brace 23 may be provided which is connected at one end to the tower 11 and at the other end to a portion of the ladder 13 which is insulated. The brace 23 i provided with a clamp 24 which may be secured to an appropriate portionof the tower 11. For receiving the opposite end of the brace 23 which is in the form of a rod, preferably composed of insulating material, a socket 25 is pivotally mounted upon the side upright of the, ladder 13 which is away from the tower 11 and toward the high tension line 17.

An elongated guide 26 isalso secured to the ladder 13 but upon the side upright closer to the tower 11. As shown, the guide 26 has ends turned toward the left side of the ladder for securing the guide 26 thereto and spacing the guide from said side of the ladder to form a guide slot for receiving the brace 23. The brace rod 23 passes between theguide 26 and the ladder 13 so as to prevent it from turning out of the plane of the brace 23 and the cross-arm angle iron 12 while the ladder 13 is being used or is being brought into the position of use. A clamp 28 on the guide 26 with a tightening, knurled nut 27 is also provided for securing the brace rod 23 against axial'movement with respect to the ladder 13 and also against angular or twisting motion around the socket 25 when the ladder 13 is in the proper position for working on a high tension line 17. I

In order to make use of the ladder 13 the lineman climb the tower 11 using conventional means for climbing such as rungs (not shown) built in to the tower 11 or otherclimbing equipment or means and hangs the ladder 13 upon the horizontal'member 12 near the tower 11. He then fastens the brace 23 by securing the clamp 24 and slides the upper end of the ladder 13 out as shown in the dashed-line position 13' with the. brace rod 23 near the lower end of the guide 26 and the rod 23 inserted in the socket 25 but not secured. It is likewise inserted in the clamp 28 but not secured.

The workman then turns-down lightly on the fastening nut 27, only sufiiciently to provide a snubbing action in the passage of the clamp 28 along the rod 23. and steps upon the rungs 18, allowing, the ladder 13 to swing out to the position shown in full lines; Thereupon, he turns the nut 27 down to secure the ladder 13. While he is still touching the rungs 18, the workman clamps the clamp 22 upon the line 17 and performs the necessary work on the line 17. After the work has been completed, he disconnects the clamp 22, releases the knurled nut 27 and pulls himself toward the tower 11 by grasping the brace rod 23. Thereupon he steps upon a rung or platform (not shown) It will be understood that the workman upon the tower 11, disengages the

hooks

14 and 15 and the clamp 24 and descends from the tower 11 while carrying the ladder 13.

Ladders constructed in accordance with the invention may also be employed for working upon electrical connections to high tension lines in sub-station structures, pole lines, or the like, which are at such heights as may conveniently be reached by portable ladders. For example, as illustrated in FIG. 2, an extension ladder 31 may be employed of a type capable of being mounted upon a truck 32. The ladder 31 is in two parts, a lower part 33 composed of an insulatorsuch as plastic impregnated fiber and an upper part 34 composed of a conductive metal,'preferably a light weight metal such as aluminum or magnesium alloy. The structural and mounting features of such mobile or truck carried ladders are conventional and need not be described other than to point out that the lower portion 33 of the ladder is pivotally mounted, bypivots 35 upon the truck 32 and is provided with a conventional hydraulic elevating mechanism 36 including a cylinder 37 and a piston (not shown) with a piston rod 38 connected to a frame work 39 slideably mounted upon the ladder portion 33 and secured to the lower end of the conductive metallic ladder section 34. The arrangement is such that when hydraulic pressure is applied to the cylinder 37 the insulated ladder section 33 rises, pivoting around the pivot 35 and the conductive metal section 34 is slid outward and upward. The piston rod 38 i provided with an insulated section 41 so as to insulate the conductive metal portion 34 of the ladder from the ground potential or anything which may be electrically connected to or grounded to the truck 32, its body or its chassis. v

The workman 42 climbs the ladder after it has been elevated to the position illustrated in the drawing, climbing up the insulated portion 33.50 as to become insulated from the truck 32 and from ground potential and climbs to the rungs of the conductive metal portion 34 so that he is at the same electrical potential as this portion of the ladder. Thereupon as in the first describedembodiment, he brings the clamp 22 into electrical contact with a high tension line or bus bar 43. Any momentary arcing between the clamp 22 and the high tension conductor 43 as the clamp comes close to the conductor 43, supplie sufi'icient current to charge the conductive metal ladder portion 34 and the body of the workman to the electrical potential of the conductor 43, whereupon the clamp 22 is secured to the conductor 43. The workman 42 is accordingly at the same electricalpotential as the high tension conductor 43 and may work thereon touching the same with his bare hands or through tools and make use of ordinary gloves without danger of electrical shock or the passage of electrical current through his body.

. FIG. 3 illustrates a form of the invention suitable for use where the high tension electrical conductor 17 is not so far above the earth or ground 44 that power equipment is needed for erecting the ladder and no other climbing means are required for reaching the position or the proximity of the high tension line '17. In this embodiment of the invention, a simple ladder 45 is employed which is composed of insulating material throughout except near the upper end Where a sheet-metal structure 47 is provided. The structure 47 corresponds to the rungs I13 Ganil side uprights of sheet-metal frame work 19 of If desired, an adjustable metallic platform 46 may be provided. For supporting the platform 46, the metallic or other conducting frame work 47 is secured to the insulator ladder 45, hinged to the platform 46 so as to make good electrical contact between the frame work 47 and the platform 46. In order to permit folding the platform 46 into the plane of the ladder 45 when the ladder is being carried, adjustable braces 48 may be provided which are secured to portions of side uprights 49 by means of screw.-

and-wing nut fasteners 51. As in the other embodiments of the invention a connecting cable 21 is provided, which is connected at one end to the metallic frame work 47 or directly to the metallic platform 46 and is provided with the clamp 22 for connection with the high tension line 17.

Simple means such as hooks 52 are provided at the upper ends of the side uprights 49 for securing the upper end of the ladder 45 to the high tension line 17 while the lower end rests upon the earth 44. It will be understood that the ladder 45 is chosen to be of a length somewhat greater than the elevation of the high tension line 1-7 above the earth 44 so that the ladder 45 slants sufliciently for stably supporting a workman as he climbs the ladder 45 up to the platform 46 and while he stands thereon .to secure the clamp 22 to the line 17 and perform any necessary work upon the line 17.

Although the ladder 45 has been shown as a simple ladder without extension sections, it will be understood that the invention does not exclude the use of an extension ladder so long as the lower portion thereof and the upper end at least are insulators so that the platform 46 will be insulated from the earth 44 and the platform 46 will not attain the potential of the high tension line -17 until after the workman has stood upon the platform 46 so as to equalize the potential between himself and the platform 46 before bringing the clamp 22 into electrical connection with the high tension line 17 for the purpose of equalizing the potential between the workman and the high tension line 17 and preventing any current from passing through his body, any necessary currents passing instead through the conductor 21.

Certain embodiments of the invention and certain methods of operation embraced therein have been shown and particularly described for the purpose of explaining the principle of operation of the invention and showing its application, and it will be obvious to those skilled in the art that many modifications and variations are possible, and it is intended therefore, to cover all such modifications and variations as fall within the scope of the invention.

What is claimed is:

1. Apparatus for working an energized conductor which is supported in space and insulated relative to the earth, said apparatus comprising a ladder of insulating structural material, means for supporting the ladder with a portion thereof in proximity to an energized conductor to be Worked upon, means comprising an electrically conducting surface on said portion of the ladder to enable a workman to stand at said portion of the ladder in insulated relation to the earth, and flexible electrically conducting means for connecting the electrically conducting surface portion of the ladder to the energized conductor for energizing a workman standing on the said electrically conducting surface to the potential of said conductor.

2. Apparatus as in claim 1, wherein the ladder is in extensible form with a lower end being insulated and having mobile support therefor and the upper end is the electrically conducting surface portion thereof, whereby the mobile support may be brought into the proximity of electrical energized conductor with the conductive surface portion of the ladder in working proximity to the conductor for enabling a workman to mount the ladder to the conductive portion thereof before said portion is energized to the potential of the conductor.

3. Apparatus as in claim 1, wherein the conductive surface portion of the ladder is provided with a conductive platform for supporting a workman electrically connected to the means for energizing the workman to the potential of the conductor.

4. Apparatus for working an energized conductor insulatingly supported from a cross-arm, said apparatus comprising a ladder comprising insulating structural material having a bracket at one end for pendularly supporting the ladder upon the cross-arm with a portion thereof in proximity to the energized conductor, the ladder having a length as great as the distance between the cross-arm and the conductor, means for providing said portion of the ladder with electrically conducting surfaces for enabling a workman standing at the conductive portion of the ladder to be energized to the potential of the conductor, and flexible electrically conducting means for making an electrical connection between the conductive portion of the ladder and the conductor.

5. Apparatus as in claim 3, wherein the cross-arm is supported by a tower and a portion of the ladder between the bracket and conductive portion thereof is provided with a brace adapted to be conducted to the tower for steadying the ladder while a workman is working thereon.

6. Apparatus as in claim 4, wherein the brace is pivoted at one end to a side of the ladder.

7. Apparatus as in claim '5, wherein the pivoted brace has a pivot at the side of the ladder away from the tower and toward the energized conductor and an elongated guide, extending parallel to the ladder, spaced therefrom to form a brace-receiving guide slot, is provided on the other side of the ladder insulated from the conductive portion thereof, the guide having ends secured to said other side of the ladder, the brace extending through said guide slot and the guide thereby subtending the angle through which the brace may be pivoted and retaining it in a plane parallel to the plane of the ladder.

8. Apparatus as in claim 7, wherein an adjustable clamp is provided for fixing the angle of the brace with respect to the ladder.

9. Apparatus for working an energized conductor which is supported in space and electrically insulated relative to the earth and a predetermined height above the earth, said apparatus comprising a ladder of greater length than the distance between the conductor and the earth with hooks at the upper end of the ladder adapted to be hooked over the the conductor for supporting the ladder in a position slanting upward to the conductor, the portion of the ladder adjacent the hooked end thereof being provided with electrically conducting surfaces for supporting the workman in working proximity to the conductor and means for making an electrical connection between said conductive surface portion of the ladder and the electrical conductor for energizing the workman to the potential of the conductor.

10. Apparatus as in claim 9, wherein a platform is mounted upon the portion of the ladder which is electrically conducting for supporting a workman and the platform is electrically connected to the conducting portion of the ladder.

References Cited by the Examiner UNITED STATES PATENTS 1,760,803 5/30 W'irth l82206 1,890,029 12/32 Delfs 18287 2,277,187 3/42 Transtrom 174-51 2,862,650 12/58 Scott 182-46 2,936,848 5/60 Hall 18246 2,981,362 4/61 Troche 182-46 FOREIGN PATENTS 920,149 11/54 Germany.

OTHER REFERENCES Publication: Electrical World, dated Nov. 25, 1957, pg. 24, located in the Scientific Library.

HARRISON R. MOSELEY, Primary Examiner.

G. LEO BREHM, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,196,980 July 27, 1965 Harold L. Rorden It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6, line 13, for the claim reference numeral "3" read 4 line 16, for "conducted" read connected line 18, for the claim reference numeral "4" read 5 line 20, for the claim reference numera1" read 6 column 6, line 40, strike out "the", second occurrence.

Signed and sealed this 18th day of January 1966.

(SEAL) Attest:

ERNEST W, SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents

Claims

1. APPARATUS FOR WORKING AN ENERGIZED CONDUCTOR WHICH IS SUPPORTED IN SPACE AND INSULATED RELATIVE TO THE EARTH, SAID APPARATUS COMPRISING A LADDER OF INSULATING STRUCTURAL MATERIAL, MEANS FOR SUPPORTING THE LADDER WITH A PORTION THEREOF IN PROXIMITY TO AN ENERGIZED CONDUCTOR TO BE WORKED UPON, MEANS COMPRISING AN ELECTRICALLY CONDUCTIANG SURFACE ON SAID PORTION OF THE LADDER TO ENABLE A WORKMAN TO STAND AT SAID PORTION OF THE LADDER IN INSULATED RELATION TO THE EARTH, AND FLEXIBLE ELECTRICALLY CONDUCTING MEANS FOR CONNECTING THE ELECTRICALLY CONDUCTING SURFACE PORTION OF THE LADDER TO THE ENERGIZED CONDUDTOR