US3649740A

US3649740A - Pole-top structure for electric distribution lines

Info

Publication number: US3649740A
Application number: US681795A
Authority: US
Inventors: John R Boyer; Charles C Scarlett
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-11-09
Filing date: 1967-11-09
Publication date: 1972-03-14
Anticipated expiration: 1989-03-14

Abstract

A compact inverted-delta polyphase electric distribution line carried on poles is disclosed in which the conductors are attached to pole-top structures for supporting the middle conductor above the pole top but at a substantially lower level than the two outside conductors. In a preferred form, the poletop bracket consists of a pair of telescoping angle members adapted to be adjusted to pole tops of varying diameter. Secured to the upper surface of the outer of the telescoping angle members is a horizontal spacing member having at its ends sockets oriented upwardly and outwardly which receive insulating extension arms which extend divergently upward and have at their outer ends insulator pins for supporting insulators for carrying the outer two wires of the three-wire distribution line. At the center of the spacing member atop the pole, a vertically disposed pin is provided having thereon an insulator for carrying the third or middle wire of the three-wire system at a substantially lower level than the two outside wires. An alternate bracket embodiment is also disclosed for carrying the middle wire of the three-wire system above the pole top but at a substantially lower level than the two outside wires.

Description

United States Patent Boyer et al.

[ Mar. 14, 1972 [54] POLE-TOP STRUCTURE FOR ELECTRIC DISTRIBUTION LINES [22] Filed: Nov. 9, 1967 [21] Appl,No.: 681,795

OTHER PUBLICATIONS New Look in Pole Top Designs, Electrical World, Vol. 162, No. 18, Nov. 2, 1964, page 76.

Eight New Ways to Clean Up Your Overhead System," Electrical World, Vol. 163, No. 14, Apr. 5, 1965, pages 96 and 97.

Primary ExaminerLaramie E. Askin AttorneyPaul & Paul [57] ABSTRACT A compact inverted-delta polyphase electric distribution line carried on poles is disclosed in which the conductors are attached to pole-top structures for supporting the middle conductor above the pole top but at a substantially lower level than the two outside conductors. In a preferred form, the poletop bracket consists of a pair of telescoping angle members adapted to be adjusted to pole tops of varying diameter. Secured to the upper surface of the outer of the telescoping angle members is a horizontal spacing member having at its ends sockets oriented upwardly and outwardly which receive insulating extension arms which extend divergently upward and have at their outer ends insulator pins for supporting insulators for carrying the outer two wires of the three-wire distribution line. At the center of the spacing member atop the pole, a vertically disposed pin is provided having thereon an insulator for carrying the third or middle wire of the threewire system at a substantially lower level than the two outside wires. An alternate bracket embodiment is also disclosed for carrying the middle wire of the three-wire system above the pole top but at a substantially lower level than the two outside wires.

4 Claims, 5 Drawing Figures PATENTEUMAR 14 I972 3, 549 74 sum 1 OF 2 INVENTORS.

JOHN R.BOYER BY CHARLES c. SCARLETT WWAW ATTORNEYS.

PATENTEDMAR 14 I972 3, 649,740

SHEET 2 [IF 2 INVENTOR.

JOHN R. BOYER CHARLES C. SCARLETT ATTORNEYS.

FOR ELECTRIC DISTRIBUTION LINES FIELD OF THE INVENTION POLE-TOP STRUCTURE DESCRIPTION OF THE PRIOR ART The present invention relates to pole line construction for electric distribution systems employing the compact so-called armless construction in which no cross arms are employed. This compact pole-top design is advantageous in that it uses less space through heavy tree growth, and in that it improves the appearance of the line. The three conductors of the threephase distribution line are supported at the pole top on pin insulators in delta configuration, the space between the conductors being typically about 25 inches. Because of the likelihood, at this reduced clearance, of the conductors swaying in the wind and making midspan contact with each other, they are conventionally provided with sufficient insulation for protection from phase-to-phase voltage breakdown. Typically, the conductors are insulated for half the phase-to-phase nominal operating voltage which, for three-phase systems, is substantially less than the phase-to-ground voltage.

In the prior art armless pole-top fixtures, the pin insulators of the delta configuration are so supported that the middle wire is carried at a substantially higher level than the outside wires. A typical pole-top support structure of this type is shown in Richards et al. Pat. No. 2,056,366. In such prior art constructions, the two outside conductors at the base of the triangle can be worked upon safely from a portable platform supported on the pole, or from insulated-boom bucket trucks when the work is to be done in midspan, while the lines are energized, but live handling of the apex or ridge conductors presents a substantial hazard. Such prior art distribution circuits of nominal kv. phase-to-phase voltage are now customarily handled while energized, with the linemen using rubber insulating protective equipment such as rubber gloves, sleeves, line hose and blankets, for protecting them from contact with the energized conductors. But with present trend toward distribution circuit voltages of 13.2 kv. and higher, while work may be performed safely on the two outer conductors of a 13.2 kv. line when they are energized, work may not be safely performed on the energized apex or ridge conductor even with the best of insulating equipment. Accordingly, the 13.2 kv. (or higher) line is generally deenergized when the lineman is required to interpose any portions of his body between the lateral conductors in order to work on the apex conductor.

SUMMARY OF THE INVENTION The present invention permits a lineman on a portable platform to work safely on any one of the three conductors of a l3.2 kv. (or higher) three-wire distribution line without deenergizing the lines. This is accomplished by providing an inverted-delta pole-top bracket. That is, the apex of the delta is at the bottom, rather than at the top. The middle or intermediate conductor is thus supported below the outside or lateral conductors, with all three conductors being above the pole top. In brief, the present invention provides a three-phase distribution pole-top pin-type insulator bracket utilizing reduced space technique in which the middle or intermediate conductor of the three-wire line is carried above the pole top but at a substantially lower level than the outside or lateral conductors.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view showing a preferred form of three-phase distribution pole-top pin-type insulator bracket;

FIG. 2 is a view, in section, looking along the line II1I of FIG. 1;

FIG. 3 is an elevational view of an alternate form of inverted-delta pole-top structure;

FIG. 4 is a side view of the same shown in F IG, 3;

FIG. 5 is a fragmentary perspective view of an inverteddelta three-phase distribution line.

pole-top structure as is DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred form of inverted-delta pole-top bracket of the present invention is shown in FIG, 1 and is seen to comprise a pair of Lshaped channel members 11 and 12 disposed in facing relation with their vertical legs adapted to be bolted, as by bolts 13, to the top of the pole 10. The transverse leg of the one L-shaped channel member 11 is received in telescoping fashion within the transverse leg of the other L-shaped channel member 12. As seen in section in FIG. 2, the lower edges of the channel of the transverse leg of the outer L-shaped member 12 may preferably be provided with inwardly extending flanges 14 for supporting the transverse leg of the channel member 11. The telescoping arrangement of the transverse legs of the channel members 11 and 12 allows the bracket to accommodate for different diameters of pole top.

A lateral spacing member 15 is secured, as by welding to the upper surface of the outer transverse leg, i.e., the transverse leg of channel member 12. At opposite ends of the lateral spacing member 15 are rectangular holders or sockets 16 and 17, the projected center axes of which are coplanar and divergent upwardly and intersect in the region of the top of the pole.

Inserted in the holders or sockets l6 and 17, and secured therein as by epoxy cement, are insulating

extension arms

18 and 19 which project divergently upwardly. The

insulator arms

18 and 19 may comprise a laminated hickory core encapsulated in compression-molded glass fiber reinforced plastic, similar to the main body of the Cat. No. OCS-l F iberglas Insulating Pole Top Pin manufactured and marketed by Highline Products Company of South Norwalk, Conn. and shown in their catalogue dated Apr. 1967.

Fitted into the outer ends of the insulating

arms

18 and 19, and epoxy-cemented thereto, are conventional Fiberglas

pins

20 and 21, carrying the

insulators

22 and 23 to which are secured, as by

lashing wires

24 and 25, the

outside wires

26 and 27 of the three-wire distribution line.

A reinforcing web 29 is connected between the two sockets l6 and 17 of the lateral spacing member 15, and at the center of the web 29 is a socket 30, shown to be of circular cross section, for receiving a Fiberglas pin 31 which is cemented in the socket 30 as by epoxy cementv Pin 31 carries the middle insulator 32 to which is lashed, as by lashing wire 33, the middle line conductor 34.

The wires or

conductors

26, 27 and 34 maybe insulated, as illustrated, such insulation being suitable for withstanding half the phase-to-phase nominal operating voltage.

It will be seen that the inverted-delta pole-top bracket, illustrated in FIG. 1 and described above, carries all three conductors above the pole top with the

outer wires

26 and 27 at a substantially higher level than the middle or intermediate wire 34. This enables a lineman to work safely on a 13.2 kv. (or higher) energized line from a pole platform or bucket truck on either of the

outer wires

26 and 27, or on the middle wire 34, without having to interpose any part of his body between the outer wires.

Although three-phase lines have been used heretofore in which one conductor is disposed below and between the other two conductors, such lines have used midspan conductor spreaders to maintain desired spacings, which are relatively quite small. The compact inverted-delta line of the present invention has at least two substantial advantages over such prior art spreader lines.

First, because the conductors of the prior art midspan spreader lines are, for practical reasons, in relatively quite close proximity to each other, it is hazardous at voltages of 13.2 kv. and above to do any work on them while they are energized. In applicants construction, however, the spacings are substantial enough to permit all three conductors to be worked on while energized, without hazard. Secondly, in the prior art midspan spreader lines, the conductors are all supported from locations laterally offset from the poles on crossarms or the equivalent mounted well below the top of the poles. In contrast thereto, in applicants construction, the conductors are disposed at substantial distances above the pole tops and, accordingly, for the same conductor-to-ground clearance, substantially shorter and therefore substantially less expensive poles may be used.

Since FIG. I is a perspective illustration, the difference in the elevational levels of the middle wire 34 as compared with the

outside wires

26 and 27 is not as evident as it might be. The illustration in FIG. 3 is clearer on this point. In FIG. 3 it is clearly evident that the middle insulator 53 is at a substantially lower level than the

outside insulators

45 and 46.

FIGS. 3 and 4 show an alternate bracket assembly for supporting the three-wire system in inverted-delta arrangement above the pole top. In FIGS. 3 and 4,

bracket elements

40 and 50 are secured, as by a pair of bolts 39, to opposite sides of the top of pole 10. The bracket element 40 has a generally rectangular base and welded thereto are a pair of

divergent sockets

41 and 42. The angle between the two axes of the two

sockets

41 and 42 may be of the order of 60. Fitted into each of the holders or

sockets

41 and 42 and cemented therein, as by epoxy cement, are the insulating

extension arms

43 and 44, having at their outer ends pinlike terminations which carry the

insulators

45 and 46. The

arms

43 and 44 may be of Fiberglasreinforced plastic, such as epoxy.

The bracket element 50, on the opposite side of the pole 10, has but a single socket 51 for receiving the vertically disposed pin 52 which may be of Fiberglas-reinforced plastic and which carries the middle insulator 53.

What is claimed is:

1. A pole-top bracket assembly for carrying the three wires of a three-wire electrical distribution system above the top of the pole, said bracket assembly comprising:

a. bracket means adapted to be secured to the pole top,

b. first and second insulating extension arms supported in said bracket means in upwardly divergent positions,

c. pin insulators carried at the outer ends of said extension arms for carrying the outer wires of the three-wire distribution system, and

d. a pin insulator supported on the top of said bracket means between and at a substantially lower level than the pin insulators on said extension arms for carrying the middle wire of said three-wire distribution system,

. said bracket means including a pair of L-shaped channel members the transverse legs of which interfit in telescoping fashion for accommodating said bracket means for varying-diameter poles.

2. Apparatus according to claim 1 characterized in that said bracket means also includes a transverse spacing member secured to the outer of said Lshaped interfitted transverse legs, and further characterized in that said spacing member is provided at its outer ends with divergent sockets for receiving said insulating extension arms.

3. Apparatus according to claim 2 further characterized in that said transverse spacing member includes a center socket, and a pin in said center socket for receiving the pin insulator which supports the middle wire.

4. A compact aerial polyphase electric distribution line comprising three conductors in inverted-delta configuration with one of said conductors intermediate of and at a lower elevation than the others, supported on respective conductorcarrying assemblies mounted on longitudinally distributed poles, each said assembly comprising:

a. bracket means secured to the pole top, including 1.a first bracket element disposed on one side of said pole top, 2.a second bracket element disposed on the opposite side of said pole top, and 3.bolt means cooperatively associated with said first and second bracket elements and extending through said pole top for securing said bracket elements to said pole top,

b. conductor-carrying insulator means mounted on said first bracket element for supporting the intermediate conductor vertically above the pole top,

c. conductor-carrying insulator means mounted on said second bracket element for supporting the two upper conductors above and in laterally spaced relation to and on either side of said intermediate conductor, comprising two insulating arms extending upward and divergently outward from said second bracket element, said arms having axes which are coplanar and intersect in the region of said pole top and each of said arms terminating in an insulator to which the respective upper conductor is secured.

Claims

1. A pole-top bracket assembly for carrying the three wires of a three-wire electrical distribution system above the top of the pole, said bracket assembly comprising: a. bracket means adapted to be secured to the pole top, b. first and second insulating extension arms supported in said bracket means in upwardly divergent positions, c. pin insulators carried at the outer ends of said extension arms for carrying the outer wires of the three-wire distribution system, and d. a pin insulator supported on the top of said bracket means between and at a substantially lower level than the pin insulators on said extension arms for carrying the middle wire of said three-wire distribution system, e. said bracket means including a pair of L-shaped channel members the transverse legs of which interfit in telescoping fashion for accommodating said bracket means for varyingdiameter poles.

2. Apparatus according to claim 1 characterized in that said bracket means also includes a transverse spacing member secured to the outer of said L-shaped interfitted transverse legs, and further characterized in that said spacing member is provided at its outer ends with divergent sockets for receiving said insulating extension arms.

4. A compact aerial polyphase electric distribution line comprising three conductors in inverted-delta configuration with one of said conductors intermediate of and at a lower elevation than the others, supported on respective conductor-carrying assemblies mounted on longitudinally distributed poles, each said assembly comprising: a. bracket means secured to the pole top, including 1.a first bracket element disposed on one side of said pole top, 2.a second bracket element disposed on the opposite side of said pole top, and 3.bolt means cooperatively associated with said first and second bracket elements and extending through said pole top for securing said bracket elements to said pole top, b. conductor-carrying insulator means mounted on said first bracket element for supporting the intermediate conductor vertically above the pole top, c. conductor-carrying insulator means mounted on said second bracket element for supporting the two upper conductors above and in laterally spaced relation to and on either side of said intermediate conductor, comprising two insulating arms extending upward and divergently outward from said second bracket element, said arms having axes which are coplanar and intersect in the region of said pole top and each of said arms terminating in an insulator to which the respective upper conductor is secured.