US2233826A - Combination load clamp and ground set - Google Patents

Description

March 1941- D. ALLISON 2,233,326

COMBINATION LOAD CLAMP AND GROUND SET Filed Aug. 25, 1939 2 Sheets-Sheet 1 Jazzy/as [57/115017 March 4, 1941. D. ALLISON COMBINATION LOAD CLAMP AND GROUND SET Filed Aug. 25, 1939 2- Sheets-Sheet 2 Patented M11124, 194i communion LOAISJEQILAMP AND GROUND Douglas Allison, Fort Worth, Tex., assignor of fifty-one per cent to Virgil Lowric, Fort Worth,

Tex.

Application August 25, 1939, Serial No. 291,989

3 Claims.

This invention relates to electrical devices and more particularly to an electric safety device in the form of a combination load clamp and ground set.

One object of this invention is to provide a meansfor short-circuiting a break in a power line whereby electricians can safely repair the line without completing the circuit through the broken parts thereof.

Another object of this invention is to provide means for grounding power lines to preclude the possibility of the lines becoming energized while workmen are working on them.

Still another object of this invention is to provide a readily manufactured apparatus which is relatively inexpensive but highly satisfactory.

A further object of this invention is to provide a highly eflicient safety device which can be readily and easily attached to or detached from power lines. I

Other objects and advantages of this invention will appear from the following description taken in connection with the accompanying drawings.

In the drawings, wherein like reference characters indicate corresponding parts in the various figures Figure 1 is a partial perspective view showing the use of the. device, incorporating features of this inventive concept, as a load clamp.

Figure 2 is a vertical cross-section through a complete load clamp and ground set, incorporating features of this inventive concept.

Figure 3 is a plan view of the device shown in Figure 2 and taken substantially on the line 3--3 thereof, showing parts of the device in section.

Figure 4 is a transverse cross-section of one of the elements of the device corresponding to a view substantially on the line 4-4 in Figure 2.

Figure 5 is a partial side elevation of the circuit completing portion of the device.

Figure 6 is a partial perspective view showing the utilization of this invention for completing a ground connection upon a three-phase transmission line.

Figure 7 is a partial elevation view, illustrating the incorporation of a fusing device in the combination load clamp and ground set.

Considering the drawings in greater .detail, the device as shown in Figure 1 incorporates features of this inventive concept and is shown as used for short-circuiting a break I I in the power line Ill. The figure shows the usual pole I2 having across-arm l3 carrying insulators I4,

upon which are secured the power line wires I5, I6 and I0. The cross-arm is bolted to the pole by a bolt I1 and braced into position by the angle braces I8, which are also secured to the pole at I9 and to the cross-arm 20 at 2I. The wire III has a break at II with that end hanging loose, and oppositely having positioned thereon a sleeve 22 for making connection between the parts.

The two ends of the line have been engaged by wire grips. 23 and 24 with wire stretching means 25, comprising the usual block and tackle with line 26 extending to the ground forpulling the same together. v

In a situation of this type, with two men working to repair the line, and with the power still on the line, it is possible that one man working at the end 22 and the other working on the end I I may come in contact with each other completing a circuit through their bodies; resulting in serious injury or death to both. It is-for the purpose of precludingsuch accidents that the present device is developed.

The device as here being used short-circuits a break in the circuit by means of conductor 21, which is connected at one side of the broken circuit by means of a clamp 28, and to the other side by means of asimilar clamp 29. This short-circuit allows the linemen to-work with the broken ends of the line since there is no difierence of potential between the points II and 22.

The device comprises a relatively long wooden pole of appropriate length 39, having a clamp 28 at its upper end. This clamp comprises a metal sleeve 3| having an enlarged cylindrical portion for receiving the upper end 32 of the pole. and is secured thereto by means of a pin 33 passing through the pole and sleeve. The upper end of the sleeve is shouldered at 34 having a reduced cylindrical end 35 extending outwardly therefrom. This hollow boss or reduced end 35 is keyed at 36 to a threaded member 31 hereinafter described.

The relatively fixed member of the clamp comprises a hollow sleeve 38 having a clamp jaw 39 extending from one end and a flange 40 extend ing from the opposite end. The jaw 39 has a recess 4| for engaging the power line. The upper end of the sleeve'38 is undercut at 42 to receive enlarged end 43 of the screw 31. This head con tains a. peripheral channel 44, which receives the end of a lock-screw 45 to hold the same rotatable within the clamp shell, but to preclude relative longitudinal movement of the threaded, member 31.

The other clamp element comprises a jaw 88 having complementary recess 81 for cooperation with the recess II. This Jaw has a central cylindrical portion 81 which is internally threaded and arranged to engage the threaded screw 31. The insulating short-circuiting conductor 21 is secured to the flange 48 by means of set-screw 88 iirmly gripping an end l8 0! the conductor.

The part Just described operates in the following manner: The wooden pole is grasped in the hand, raising the clamp 88 into contact with one conductor oi the power line and the pole III is then quickly rotated so as to screw the clamp member 88 into nrm engagement with the line. The two clamps having ilrmly gripped the power line, between their jaws II and 51, the other portions 0! the device can then be utilized.

A similar clamp 28 is arranged at the upper end of the double pole device, comprising the poles Ill and II. The clamp 28 is similarly constructed to the clamp 28 and the parts will not be re-described, but will be merely numbered with correspondin numerals each having a prime. The sleeve 8|, as observed in the lefthand portion of Figure 2, is longer than the sleeve portion II in view oi the fact that it carries a metal bracing bracket 52, which serves as well as a bearing guide 88 and 54, for the double poles. One or more clamps of this type may be placed in other spaced positions to make the poles more suitably operated. The upper clamp or brace 82 also serves as a static or other guard stopping any tendency of current to run down the pole and causing it to be conducted between the metal parts.

In the double pole construction, the bracket 88' is longer than the bracket 88, and is provided at its outer end with a hollow substantially cylindrical boss portion 85, extending downwardly into a hollow tapered skirt 58. The central aperture 88 of the boss is irregular, being broken along the diameter by the inwardly extending integral key portions 58. This construc- 'tion is provided for cooperation with the remaining parts of the mechanism now to be described.

The pole 8| has a reduced portion 60 about which is secured a metallic sleeve 8|, which serves as a bearing riding through the apertured end 88 01' the bracket 52. The pole continues in its normal rise upwardly, and carries a conducting ring 82 provided with an outwardly extending apertured boss 63. This boss receives the other end 64 of the conductor 21, which is locked therein by set-screws 65. The ring 82 is pinned to the shaft by a pin 68, and the outer portion is tapered at 51 so as to firmly engage the inner surface 68 of the skirt. The upper end 01 the pole BI is reduced in section and carries a metal cap 68 which has a downwardly extending slotted sleeve Hi pinned to the pole at II. The slotted sleeve is arranged to receive the keys is and to thereby maintain the parts, during relative axial movement, in proper alignment.

The sides of the skirt 58, at right angles to the keys 88, are slotted at I! to provide for a bayonet type connection with pin "carried upon the ring 82. The key and slot connections retain the parts properly aligned so that the pin 14 will be received in the entrance 15 of the slot. Each side of the slot has lower tapered seats 18 and Il so that turning of the pole causes the pin 74 to ride o e 8 t pon the cam seat I8, or to the left upon the cam seat TI, thereby firmly engaging the surfaces 81 and 88 to provide a good conducting connection. a

The axial movement oi. the pole 5| completes an electrical circuit between the conducting parts 0! the clamp 28 and its integral skirt 88, and the parts 01' clamp 28 through the conductor 21 and the conducting connection thus described.

In Figure 6, a slightly diilerent use oi this device is shown, with parts corresponding to those illustrated in Figure 1 being shown with similar numeralshaving a prime. In the use illustrated in Figure 8, the combination load clamp and ground set is shown clamped to power lines 88, 8| and 82 with the opposite ends clamped to a ground line 88 connected to ground by conductor 88.- The parts are in position, but the ground connections have not been completed in the illustration since the skirts 88 have not been connected to the member 82 for the purpose of completing the circuit. The ground connection will be completed, however, by the simple operation of moving the skirt and ring together.

In Figure l, the equipment is illustrated as being used to shunt the break in the power line. If the power line is hot," the operation of the device restores the circuit around the break in an efllcient manner which will allow workmen to work upon the line during the absence of a difl'erence of potential between the points of break, which results from the restoration of the circuit by the load clamp and ground set, as herein described.

In the foregoing description, the word shortclrcuit is used in its general sense to mean the formation of a relatively low resistance current path about a localized relatively high resistance path which may be of infinite resistance or of lower resistance. In the use of the device as illustrated in Figure 6, it will likewise be appreciated that where the power line is carried upon a metallic tower structure which is grounded, that the ground clamps can be connected directly between the power lines and the tower steel work.

With the proper operation of this device, it is almost impossible for a workman to get a shock or an accidental flash burn from short circuiting the line if it is "hot or energized, as the contact points of the parts 62 and 56 are always open when it is initially applied, and are only closed after the clamps are secured to the line, ground wire, or metal tower, as is required.

Another very valuable use for this device is in the fact that it can be used to rescue a man that has already come in contact with a line of higher voltage than the rescue crew is equipped for trimming or cutting to clear the person being rescued. In such a case, by clamping the device between the two conductors and then closing the contacts, a direct short-circuit can be created on the power line which would immediately trip the circuit in the sub-station or power plant, to thereby enable the workmen to free an unconscious person without subjecting the rescuers to unnecessary danger or risk.

In Figure '7 the load clamp is illustrated as having incorporated therein a fusing device to render the apparatus suitable for testing a line for short-circuits on grounds. As shown, the fuse comprises an insulating tube 86, the opposite ends of which are completed by metal members 81 and 88, being provided respectively with sleeve portions 89 encircling the tubing, and with laterally extending bosses 9B. The upper member is threaded at 9| to receive a cap 52 thereon,

which latter is arranged to hold one end of the fuse 93 in contact with the metal member. The opposite end of the fuse extends through an aperture 94 in the metal member and is secured thereto by a screw 95. A screw 96 is arranged so that the line 21 can be secured to one end of the fuse element. The boss on the upper end of the fuse, is arranged to be received within the socket 40 of the line clamp to thereby make the fuse an integral part of the entire apparatus.

After a fuse has been blown, it must be replaced. In using the present device for this purpose, branch lines are first disconnected from the main circuit, and the blown fuse replaced. The load clamp is then secured to either the main line or the feeder, and with the fuse device lighter than the main line fuse, the opposite end of the clamp is connected independently to each of the branch circuits, after which the sleeve switch 6168 is closed to complete the circuit. As long as the feeder lines, being connected in, are clear, nothing will happen. As soon as a branch feeder, upon which trouble has developed, is connected, the fuse in the load clamp will blow before the station breakers or the main line fuse can be blown again. If the auxiliary fuse 86 blows, it would be a clear and definite indication that that portion of the circuit is in an unsafe condition, and must not be connected to the main line.

Although only a few of the advantages and uses of this device have been described for the purpose of clearly illustrating the operation and use,- other advantages will be readily understood by persons skilled in the art.

Although a preferred embodiment of this invention is illustrated and described, variations within the true spirit and scope of the same are to be determined by the appended claims.

What I claim is:

1. Electrical ground set comprising in com bination a pair of pole handled screw clamps having wire engaging jaws, a conductor con necting said screw clamps having a flexible portion, and a pole handled switch intercalated in said conductor having one of the contacts thereof rigidly supported by one of said clamps and the other contact movable with the flexible portion of said conductor.

2. Electrical ground set comprising in com bination a pair of pole handled screw clamps with wire engaging jaws, a lateral arm on one of said clamps, an annular switch contact on said arm, a pole supported by said arm slidable through said contact, a complementary switch contact mounted on said pole, the latter acting as a dielectric between said contacts when said switch is open, said switch being closed by longitudinal movement of said pole relative to said annular contact, and a flexible conductor connecting the pole mounted switch contact with the other clamp.

3. Electrical ground set comprising in combination a. pair of pole handled screw clamps with wire engaging jaws, a lateral arm on one of said clamps, an annular switch contact on said arm, a pole slidable through said contact, a comple m-entary switch contact mounted on said pole, a flexible conductor connecting said pole mounted contact with said other clamp, means suspending said pole from said arm, said pole acting as a dielectric between said switch contacts when so suspended, means to prevent rotation of said pole relative to said annular contact throughout the switch closing sliding movement of said pole, and latching means between said contacts for latching said switch in closed position by partial rotation of said pole.

DOUGLAS ALLISON.

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