US3259875A

US3259875A - High voltage unshielded insulated electrical jumper

Info

Publication number: US3259875A
Application number: US316596A
Authority: US
Inventors: Robert S Ewers
Original assignee: BODENDIECK TOOL CO
Current assignee: BODENDIECK TOOL CO
Priority date: 1963-10-16
Filing date: 1963-10-16
Publication date: 1966-07-05
Anticipated expiration: 1983-07-05

Description

R. S. EWERS July 5, 1966 HIGH VOLTAGE UNSHIELDED INSULATED ELECTRICAL JUMPER Filed 090i. 16, 1963 2 Sheets--Sheeil 1 July 5, 1965 R. S. EWERS HIGH VOLTAGE UNSHIELDED INSULATED ELECTRICAL JUMPER Filed Oct. 16, 1963 2 Sheets-Sheet 2 United States Patent O The present invention relates to high-voltage unshielded insulated electrical jumpers for connection t across equipment during repair, and is particularly concerned with such jumpers that may be used by linemen on highvol-tage circuits with absolute safety and rassurance so that the insulated part of the jumper may be `engaged without danger.

In the prior art, portable jumpers which are used by linemen, cannot be shielded, even though the shield is grounded, because the presence of the grounded shield is a hazard in itself, and it is not practical to attach the electrical connections to connect up a shielded system.

Therefore, jumper cables for line crew use are always unshielded and therefore, to be absolutely safe, these jumper cables of the prior fart should not be used over 5,000 volts.

Additional insulation has been used on rubber-insulated jumper cables, but they are not to be trusted, and a lineman should stay out of any Contact with them.

`Even with these precautions, the maximum voltage at which lthe jumper cables of the prior art may be used, is about l2 kv., which is about 7,200 volts to ground and is 13,000 volts between phases.

One of the objects of the invention is the provision ,of 4an improved, unshielded insulated jumper, which is safe for use on 34.5 kv. and 69 kv., `and which is so `well insulated and constructed and of such length .that

the newjumper may be made so long and so well insulated Ithat the linemen may work adjacent to, and in contact with, and between the new jumpers, .and at points remote from the metallic parts, they may engage the outside of the jumper with absolute safety.

Another object is the provision of a new insulated jumper in which the insulation is so eifective that a man cannot detect that current is running through the device when the hand is placed on the outside of the insulated portion of the jumper.

Another object is the provision of an unshielded, in-

` sulated jumper in which the conducting element is a Y* metal rod of high conductivity, protected by `an elongated plastic insulating tube, having insulating plugs in each end vfor passing the rod, and the space in the tube is filled by an inert insulating fluid under pressure, tand the length of the plastic insulating tube is so long, such as 6 feet or more, that .a lineman may work beside it without possibility of getting adjacent the energized ends of the rod.

Another object is the provision of such .a jumper which `is of minimum diameter, such as 3% inches outside'diameter, and which when filled with inert insulating gas such as sulfur hexafluoride, the insulating value of the jumper is substantially constant and safe for Ithe high voltages for which it is designed.

Another object is the provision of an improved jumper of the class described, in which the ends of the metal rod, outside the plastic tube .are permanently connected to insulated cables, as by threads, and provided with a tap 4clamp at each end to be connected to line with the use of a clamp-stick.

Another object is the provision of insulated means for supporting the new jumper on the line structure, in addition to the tap clamps and cables, and means for charging the jumper tube with an insulating fluid, and purg- "ice ing it of all air, and Ithe provision of fluid-tight joints between the plugs for the ends of the plastic tube, and the tube, and fluid-tight joints surrounding the conducting rod, so that the fluid may be under pressure, and the provision of an indicating pressure guage for constantly showing the pressure condition of the insulating fluid, so that it will be known to be safe, as long as there is no loss of pressure.

Another object is the provision of such a jumper which is absolutely safe when used up to kv. and in which there is a minimum of current leakage.

Another object is the provision of such a jumper which is simple, which has a minimum number of parts, which may be manufactured economically, land which is dependable, safe, and effective at the voltages for which it is designed.

Other objects and advantages of the invention Will be apparent from the `following description and the accompanying drawings in which similar characters of reference indicate similar parts throughout the several views.

Referring to the two sheets of drawings accompanying this specification,

FIG. 1 is a side elevational view of a high voltage unshielded insulated electrical jumper for connection across equipment during repair, on high voltage lines;

FIG. 2 is a fragmentary view similar to FIG. 1, on a larger scale, in partial section to show the details of construction;

FIG. 3 is a fragmentary elevational view taken on the plane of the line 3 3 of FIG. 2, looking in the direction of the arrows;

FIG. 4 is a fragmentary sectional view taken on the plane of the line 4 4, of FIG. 2, looking in the direction of the arrows;

FIG. 5 is a fragmentary sectional view, taken on the plane of the line 5--5, of FIG. 4, looking in the direction of the arrows;

FIG. 6 is a top plan view, taken from thetop of FIG. 1;

FIG. 7 is a bottom plan view, taken from the bottom of FIG. l;

FIG. 8 is a fragmentary sectional view, taken on the plane of the line 8-8, of FIG. 2, looking in the direction of the arrows;

FIG. 9 is .a fragmentary sectional view taken on the plane of the line 9-9 of FIG. 2, looking in the direction of the arrows;

FIG. l0 is a fragmentary sec-tional view, taken on the plane of the line 10-10 of FIG. 5, looking in the direction of the arrows;

Referring to FIG. l, 20 indicates in its entirety, one of the improved jumpers, supported on a high voltage line, in which the pole 22, crossarms 24, 26,

insulators

28, 30, and line 32, are shown 4in dotted'lines. The jumper is supported on the line structure by a plurality of insulating straps, only one 34, of which is visible in FIG. l. The straps 34 are attached at their ends to a pair of headed lugs, 36, 38, as shown in FIG. 2, by providing the straps with a plurality of slit apertures 40, each terminating in a round aperture 42, large enough to receive the shank 44 of each lug, behind the head 46, between the two annular surfaces 48, 50, and the length of the shank 44 in each case is sufcient to receive several layers of strap 34.

The

lugs

36, 38 have an enlarged cylindrical body S2 and an end surface 54, which is partially cylindrical, fitting against the side of the tube 56, which is made of insulating plastic, and the headed lugs have their surfaces 54 cemented to the tube 56 by an insulating cement such as epoxy. f

The lugs are preferably located on the opposite sides 3 of the tube 56, and in FIG. 6, it will be observed there are two more lugs S8, A59, supporting strap 60. The straps may be made of braided nylon, as shown, and the figures shown are merely one example of the arrangement of the straps.

The jumper has an insulating plastic tube 56, preferably vof small diameter, such as 3% inches outside diameter, and the tube 56 may be made of suitable plastic, such as rigid polyvinyl chloride plastic, and the tube 56 is provided with an

insulating plug

62, 64, in each end. A metal rod of cylindrical shape, of high electric conductivity, such as aluminum, 66, extends the full length of the tube 56, and projects from each end thereof as at 68, 70, and the rod 66 terminates in each case in a threaded bore 72.

Each end of the rod 66 is secured to the end of a conducting cable and the cable is covered with rubber insulation, and the insulation is received in a socket 80 in a fitting 82, and the conducting cable end 84 is brazed in a bore 86 in the fitting 82, which has a threaded end 88 in a threaded end 72 in the end of rod 66. The cable is thus permanently attached in the end of the rod in each case.

The rod 66 is located axially in the tube 56, and the rod passes out of the ends of the tube through axial bores 90, 92 in the

plugs

62, 64. In order to maintain the axial position of the rod 66, it is provided with one or more symmetrically located, cruciform spacers, and the spacers have a bore 96, litting the rod 66, and each spacer 94 has four arms 98, 100, 102, 104, each arm having an outer partially cylindrical surface 106, engaging Athe inner cylindrical surface 108 in the tube 56, and the position of the spacer is maintained by a diagonal pin 108a of insulation, frictionally mounted in its bore 110. The spacer may be made of linear polyethylene plastic, and engages the inside of the tube frictionally.

Referring to FIG. 1 and FIG. 3, the cables 74 and 76, are provided at their ends with standard tap clamps, 112, 112, and the tap clamps are each secured to the end of the cable by a threaded end portion, 114, passing through a bore in the tap clamp and secured by a nut 116. The threaded end portion 114 is secured to the end of the cable in each case like the other end is secured to the fitting 82. The tap clamps include the usual body 118, with an upper jaw 120, with a hole 122 for manipulation, and a movable jaw 124 mounted on a rotatable driving screw 126, threaded in bore 128, and rotatably engaging the movable jaw 124, which has guides 130, sliding on body 118, and having an `actuating eye 132 for engagement with a clampstick head. While the jumper 20 is being suspended from a crossarm, the tap clamps 112 may be secured on the projecting ends 68, '70 of the rod 66, but after the jumper is properly supported on the line structure, each tap clamp is removed from the rod 66, and secured, using-a clampstick, on the leads to the equipment being serviced. Then the equipment having been bypassed by the jumper, the leads to the equipment being serviced are cut, to be later provided with connectors to make easy later connection.

Referring to FIG. 2 and FIG. 5, the

end plugs

62, 64 maybe made o f insulating plastic such as linear polyethylene, and are provided with a cylindrical body 134, of sufficient length so that the expansion of the aluminum rod 66 relative to the plastic tube 56, will never move the plugs out of the tube, and each plug has an annular flange 136, outside the tube, and this flange is spaced from the end of the tube 56, by a clearance 138, to allow of contraction of the aluminum rod 66, relative to the plastic tube 56.

Each

plug

62, 64, has its cylindrical outer surface, 134, provided with a plurality of annular grooves of rectangular-crosssection 140, for receiving a rubber O-ring fitting tightly in the groove and projecting therefrom into fluid sealing engagement with the inside of the tube 56. Each bore 90, 9,2, in the

plugs

62, 64, is also cylindrical, and

is provided on its inside with a plurality of annular grooves 146, of the same type, for receiving O-rings 148 surrounding the rod 66, and the O-rings on the outside of the plugs are indicated at 142. Thus each plug has fluid tight sealing engagement inside the plastic tube 56,` and about the rod 66, but in some embodiments the plugs may be made fluid tight by using epoxy cement and providing a sliding joint in the rod, to permit expansion and contraction of the rod.

The rod 66, is also provided at each end with a neoprene washer 150 surrounding the rod 66 and engaged by a metal washer 152, which in turn is engaged by plastic or metal bushing, of cylindrical shape, fitting on the rod 66, and secured thereon by a through pin 156, frictionally engaged in its bores, to secure the rod relative to the tube 56. The neoprene washer 150 permits a limited contraction of the rod in the tube S6.

Each

plug

62, 64 has a bore 158, FIG. 5, with a flange at its inner end, engaging in a groove 162 in a standard tubeless tire valve 164, having a head 166, and a-n enlarged body 168, fitting in the bore 158, and having the standard valve inside, with a threaded body on a valve sleeve having an inner valve seat, a valve stem and -a spring maintaining the valve closed, and covered with a cap.

One valve is located at the top side of its plug, and the other is located near the bottom of the other plug, so that when one valve is connected to a pressure container iilled with insulating iiuid, the fluid may be admitted to the inside of the tube, and the tube may permit the air to go out -the other end, by pressing or removing the valve until the air is purged from the tube.

Another bore 170, in the plug 64, vhas a threaded counterbore 172, for receiving the threaded shank 174, of the inlet of a pressure gauge 176, facing downwardly so that its face may be visible to the lineman below the gauge. The fluid in the tube 56 is maintained under pressure of 25 to 30 lbs. and is a constant indication of the condition of the insulating uid in the tube.

The fluid which is preferably used in the tube under pressure, is sulfur hexaiuoride, and is completely inert and will not form any compounds that will later compromise its insulating qualities.

Another form of insulating fluid that may be employed is transformer oil, which should be free of any moisture, and may be maintained under pressure by a small amount of gas in the tube.

The present jumper is the first that is safe for use on 34.5 and 69 kv., and may be used where the linemen come into contact with the plastic body of the tube but are remote from the metal at the ends.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patentv of the United States, is:

1. -A high-voltage fluid-insulated jumper, comprising yan elongated rigid plastic tube extending beyond reach of any lineman when supported on a power line, two pair of headed lugs, shaped at their ends to fit the side wall of the tube, and each pair cemented to the opposite sides of the tube, the two pairs being spaced longitudinally and symmetrically on said tube, a pair of insulating straps, each strap having a plurality of slits and holes to secure the straps to the tube in position to support the tube on the line, a plastic plug fitting in each end of the tube and having an enlargement engaging the end of the tube, each plug having a cylindrical through bore, an electrically conducting rod tting in each plug and extending all the Way through the tube and spaced from the walls thereof, each plug having a Huid-tight engagement with the tube and the rod, `and said rod being xedly secured at each end to the conductor of an insulated flexible cable, and a standard tap clamp in electrical connection to the end of each cable for use in connecting the jumper assembly to the line on both sides of electrical equipment to be jumped, a pressure gauge having a iluid connection through one of said plugs for indicating the pressure condition inside said tube, a pair of standard gas valves, one of each of the valves being mounted in each plug to permit the filling of the tube with an insulating tluid, one valve being used to a uid container under pressure and the other valve being used to purge the tube of air to secure a complete filling of the tube, and an inert insulating fluid filling said tube surrounding the rod and insulating the jumper without need for shielding, up to 69 kv. or more.

2. A high-Voltage fluid-insulated jumper, according to claim 1, in which the insulating uid is sulfur-hexauoride gas under pressure.

3. A high-voltage Huid-insulated jumper, according to claim 1 in which the insulating fluid is inert, moisturefree transformer oil under pressure.

References Cited by the Examiner UNITED STATES PATENTS OTHER REFERENCES Gen. Elec. Review, February 1948, pages 35, 41, Camille et al.

BOBBY R. GAY, Primary Examiner.

20 ALFRED S. TRASK, Examiner.

Claims

1. A HIGH-VOLTAGE FLUID-INSULATED JUMPER, COMPRISING AN ELONGATED RIGID PLASTIC TUBE EXTENDING BEYOND REACH OF ANY LINEMAN WHEN SUPPORTED ON A POWER LINE, TWO PAIR OF HEADED LUGS, SHAPED AT THEIR ENDS TO FIT THE SIDE WALL OF THE TUBE, AND EACH PAIR CEMENTED TO THE OPPOSITE SIDES OF THE TUBE, THE TWO PAIRS BEING SPACED LONGITUDINALLY AND SYMMETRICALLY ON SAID TUBE, A PAIR OF INSULATING STRAPS, EACH STRAP HAVING A PLURALITY OF SLITS AND HOLES TO SECURE THE STRAPS TO THE TUBE IN POSITION TO SUPPORT THE TUBE ON THE LINE, A PLASTIC PLUG FITTING IN EACH END OF THE TUBE ON HAVING AN ENLARGEMENT ENGAGING THE END OF THE TUBE, EACH PLUG HAVING A CYLINDRICAL THROUGH BORE, AN ELECTRICALLY CONDUCTING ROD FITTING IN EACH PLUG AND EXTENDING ALL THE WAY THROUGH THE TUBE AND SPACED FROM THE WALLS THEREOF, EACH PLUG HAVING A FLUID-TIGHT ENGAGEMENT WITH THE TUBE AND THE ROD, AND SAID ROD BEING FIXEDLY SECURED AT EACH END TO THE CONDUCTOR OF AN INSULATED FLEXIBLE CABLE, AND A STANDARD TAP CLAMP IN ELECTRICAL CONNECTION TO THE END OF EACH CABLE FOR USE IN CONNECTING THE JUMPER ASSEMBLY TO THE LINE ON BOTH SIDES OD ELECTRICAL EQUIPMENT TO BE JUMPED, A PRESSURE GAUGE HAVING A FLUID CONNECTION THROUGH ONE OF SAID PLUGS FOR INDICATING THE PRESSURE CONDITION INSIDE SAID TUBE, A PAIR OF STANDARD GAS VALVES, ONE OF EACH OF THE VALVE BEING MOUNTED IN EACH PLUG TO PERMIT THE FILLING OF THE TUBE WITH AN INSULATING FLUID, ONE VALVE BEING USED TO A FLUID CONTAINER UNDER PRESSURE AND THE OTHER VALVE BEING USED TO PURGE THE TUBE OF AIR TO SECURE A COMPLETE FILLING OF THE TUBE, AND AN INERT INSULATING FLUID FILLING SAID TUBE SURROUNDING THE ROD AND INSULATING THE JUMPER WITHOUT NEED FOR SHIELDING, UP TO 69 KV. OR MORE.