GB1587233A

GB1587233A - Clamp for conductor of an overhead electricity transmission line

Info

Publication number: GB1587233A
Application number: GB3585277A
Authority: GB
Original assignee: Brush Power Equipment Ltd
Current assignee: Brush Power Equipment Ltd
Priority date: 1978-05-30
Filing date: 1978-05-30
Publication date: 1981-04-01

Description

(54) CLAMP FOR CONDUCTOR OF AN OVERHEAD ELECTRICITY TRANSMISSION LINE (71) We, BRUSH POWER EQUIP MENT LIMITED, a British Company, of Bridgend, Glamorgan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a clamp to be engaged with an electrical conductor of an overhead electricity transmission line but may be used for clamping to other cable-like elements.

The clamp is particularly intended to be used either in a spacer-damper for holding the sub-conductors of a bundle of subconductors apart from each other so that they are suspended substantially parallel with one another and also damped from transverse movement or in a spacer for holding two or more sub-conductors apart and substantially parallel one with another.

As such a clamp usually has to be clamped to a sub-conductor when the sub-conductor is suspended between pylons it is desirable that the clamp is pre-assembled and does not require a clamping bolt which has to be inserted through the clamp parts while the operator is attempting to hold the clamp parts around the conductor. An object of the invention is to provide such a bolt-less clamp.

According to the invention a clamp to be engaged with an overhead electrical conductor, a sub-conductor of a bundle of subconductors of an overhead electricity transmission line, or other cable-like element (hereinafter called " the conductor"), comprises a first clamp part having therein a first semi-cylindrical recess, a second clamp part having therein a second semi-cylindrical recess, a pair of interengageable and separable hinge-defining surfaces formed one on each of said clamp parts and which when interengaged one with the other define a hinge having an axis parallel with the axes of the recesses, thereby to permit the two clamp parts to be pivoted relatively of each other about the hinge axis to effect engagement of the two recesses coaxially around the conductor or to permit the clamp to be released therefrom, and a pin extending freely through an elongate aperture in one of said clamp parts at the side of the recess therein remote from the hinge surface, the pin having an enlarged end portion by which the pin is held from removal from the other of said clamp parts, the pin being relatively rotatable in said other part about the longitudinal axis of the pin, and a head remote from said enlarged end portion and engageable by the face of said one clamp part remote from said other clamp part, the length of the pin between said enlarged end portion and said head being sufficient to permit the two clamp parts to be pivoted away from one another about the hinge-defining surfaces to effect the release of the clamp from the conductor and to enable the hinge surfaces to be disengaged one from the other, the pin then acting to retain the two clamp parts from complete separation one from the other, the pin also having a latch member thereon extending transversely of the pin at a location intermediate said enlarged end portion and the head of the pin and arranged to pass through the aperture in said one clamp part and a corresponding aperture in said other clamp part when the pin has been turned about its longitudinal axis to align the latch member with the larger dimension of the aperture, the latch member serving to clamp the two parts together to grip the conductor therebetween after the two clamp parts have been hinged together and pivoted towards each other, the recesses have been positioned around the conductor, the latch member has been passed through the apertures in both clamp parts and the pin has been turned about its longitudinal axis until the latch member extends transversely of the apertures and bridges the sides of the aperture in said other clamp part to bear against the face of said other clamp part remote from said one clamp part.

Conveniently the aperture in said one clamp part is a slot extending outwardly with respect to the recess in said one clamp part and transversely thereto. The portion of said one clamp part defining the slot may extend in the direction of clamping movement of said one clamp part towards said other clamp part along a line inclined at an acute angle to a tangent to a circular arc struck from the hinge axis. The said portion of said one clamp part may be shaped to extend, when the clamp parts have been clamped around the conductor, between a pair of stop faces to limit relative sideways movement of the clamp parts longitudinally of the conductor.

The pin conveniently has a bulbous, bifurcated end portion remote from the head, the end portion being located in the aperture in said other clamp part, in which aperture said end portion is rotatable about the longitudinal axis of the pin and in which said end portion can be rocked transversely of the longitudinal axis of the pin, the pin being retained in the aperture by splaying apart the sides of the bulbous, bifurcated end portion thereof to form the aforesaid enlarged end portion.

The latch member on the pin may conveniently be in the shape of a barb having side faces extending at an acute angle to the longitudinal axis of the pin at each of a pair of diametrically-opposite positions, the latch member bearing against the said remote face of said other clamp part when the pin has been turned to its clamping position and the clamp parts have been pivoted together to grip the conductor therebetween.

The head of the pin may have an outward, axially-facing rib which extends parallel to the cross-line of the barb and thus the direction of the rib indicates whether the barb is in its unclamped or clamped position.

The surfaces defining the hinge may conveniently comprise a tongue extending from a first of the clamp parts and having a convex surface thereon and a socket on the second of the clamp parts, into which socket the tongue is insertable, the socket having a concave surface with which the convex surface on the tongue is engageable.

The two damp parts may each have a stop face thereon, the two stop faces being engageable, one with the other, when the two clamp parts are pivotally closed together and locked by the pin. These stop faces are provided as the clamp parts are over-tightened on clamping the conductor within the recesses.

When the clamp has been locked, the overtightening force is relaxed. The stop faces therefore prevent damage to the clamp parts during the clamping operation.

Each recess may conveniently accommodate a semi-cylindrical elastomeric liner, the two liners when closed together around the conductor co-operating to form a resiliently deformable tube in which the conductor is gripped.

Each liner may be detachable from the respective recess and have at least one circumferentially-extending rib or groove cooperable with a complementary groove or rib defined in the circumferential wall of the recess and at least one radially-extending tongue or recess co-operable with a complementary radially-extending recess or tongue in the circumferential wall of the recess.

Alternatively, each liner may be permanently bonded to the circumferential wall of the respective recess.

The clamp may be attachable to the body of a spacer-damper assembly for a bundle of sub-conductors of an overhead electricity transmission line, in which case said other clamp part would constitute an arm of the spacer-damper and have at the end thereof remote from the recess therein, a hole for receiving a pivot by which the arm is to be attached to a body of the spacer-damper assembly.

Alternatively the clamp may be formed on a spacer for holding apart side-by-side two or more sub-conductors of an overhead electricity transmission line and in that case said other clamp part may be formed on a common member on which at least one other like clamp part is formed. Thus the spacer would have two or more identical clamps each in accordance with this invention and having a common member on which each of said other clamp parts is formed.

By way of example, a clamp in accordance with this invention and provided on a pivotable arm for a spacer-damper will now be described with reference to the accompanying drawings, in which: Figure 1 is an exploded perspective view of the clamp, and Figures 2-4 are side elevations and part sectional views showing successive stages in the positioning of the clamp on a subconductor and the clamping of the subconductor in the clamp.

Referring to the drawings, the clamp for gripping the sub-conductor 40 (shown in Figures 2-4) is provided on the outer end of an arm 1 which is pivotally mounted at its other end on a spacer-damper body of which part is shown at 2 (in Figures 2-4).

The arm has a hole 3 (see Figure 1) at its said other end for receiving a torsion bearing including a resilient bush 4 and a pivot and retaining bolt 5. The method of mounting the arm is well-known in connection with spacer-dampers and is not described further herein.

The outer portion of the arm 1, with respect to the end provided with the hole 3, forms a first of the clamp parts 6, referred to hereinbefore as said other clamp part.

The second of the clamp parts is shown at 7 and has been referred to hereinbefore as said one clamp part.

Each of the clamp parts 6 and 7 is formed adjacent its radially outer end with a generally semi-cylindrical recess 14 or 15 (see Figure 1) containing a semi-cylindrical elastomeric liner 8 or 9, respectively, the two liners 8, 9 co-operating together, when the clamp parts 6 and 7 are closed, as shown in Figure 4, to form a cylindrical elastomeric tube which will be gripped around the sub-conductor 40, the latter extending co-axially through the tube formed by the liners. The liners each have a radially-extending peg-like projection 10, 11 extending outwardly therefrom and which, on assembly, is inserted in a socket 12, 13 in the respective recess 14, 15, thereby to hold the liners 8, 9 from turning in the respective recesses 14, 15. Each liner is formed with circumferentially-extending ribs 16 which, on assembly are located in circumferentially-extending grooves 17 (shown in Figure 1), thereby to transfer end thrust from the sub-conductor to the clamp parts 6, 7 and also to hold the liners 8, 9 from axial movement in the respective recesses 14, 15.

Alternatively, the liners 8, 9 may be permanently bonded in the respective recesses.

The clamp part 7 is hinged to the clamp part 6 by a detachable hinge formed by a tongue 20 extending from the clamp part 6 and insertable in an undercut socket 21 formed in the clamp part 7. The tongue 20 has a convex surface 22 which can turn in a concave surface in the socket 21, thereby providing a hinge axis parallel to the common longitudinal axis of the two recesses 14, 15 and the liners 8, 9, referring to the closed position of the clamp parts, as shown in Figure 4. The clamp parts 6, 7 are held together by a clamping pin 25, to be described in detail hereinafter. In Figure 4, the pin 25 is shown in a position in which the two clamp parts 6, 7 are clamped together.

The pin 25, as will be explained hereinafter can be turned about its longitudinal axis to a position in which it can be partly withdrawn in a downward direction, as shown in Figures 2 and 3, thereby to permit the clamp part 7 to be pivoted about the axis of the hinge 20, 21 in an anti-clockwise direction into the position shown in Figure 3, to open the liners 8, 9 and thus to release the clamp from the sub-conductor 40 or for the reverse movement to close the liners 8, 9 on to the sub-conductor into the position shown in Figure 4. When the clamp part 7 has been pivoted to the fully-open position of the liners 8, 9, the socket 21 and the tongue 20 are separable one from the other and when the hinge parts have been separated, the clamp can be removed from the conductor or placed around the conductor. When the hinge parts have been separated, the clamp part 7 will still be supported from the clamp part 6, or vice versa, by the pin 25 (as shown in Figure 2).

The pin 25 and its location in the clamp parts 6, 7 will now be described. Referring particularly to Figure 1, the pin 25 comprises a cylindrical shank 26 having at one end thereof a head 27 and at the other end a bulbous protrusion which is bifurcated into two bulbous end portions 28 by a slot extending from the bulbous end portions 28 to a pair of transverse extensions 29 which together form a latch member in the shape of a barb. The head 27 has an outwardly facing rib 30 which extends in directions parallel with the extensions 29 and therefore indicates in which direction the extensions 29, forming the latch member, are positioned.

The clamp part 7 has an extension 36 towards the pivotal end of the arm 1 and which contains an elongate slot 31. The extension 36 containing the slot 31 is inclined from the end of the slot nearer to the recess 15 towards the end nearer to the pivoted end of the arm 1 in a direction such that the end of the extension nearer to the pivoted end of the arm is at an acute angle to a tangent to a circular arc struck from the hinge axis. The shank 26 of the pin 25 passes freely through the slot 31 and so does the latch member when the transverse extensions 29 extend lengthwise of the slot.

The clamp part 6 has a hollow box-like region 39 (see Figure 1) between the recess 14 and the pivoted end of the arm 1 containing a platform 33 in which there is a slot 32 (see Figure 1). The slot 32 extends lengthwise of the arm 1 and is open at the end nearer to the pivoted end (i.e., the end provided with the hole 3) of the arm 1.

The slot 32 has a width slightly greater than the diameter of the shank 26 to enable the shank to slide and turn freely in the slot 32 but which will prevent the transverse extensions 29 from passing therethrough when the pin has been turned to position the latch member across the slot 32 to bridge the sides thereof. The slot 32 has a portion 35 intermediate its ends which is wider than the remainder of the slot 32 and is shaped to receive and locate the bifurcated portions of the shank 26 of the pin 25 immediately inboard of the bulbous end portions 28, which, after assembly of the pin 25 in the clamp parts 6, 7 will be prevented from passing through the slot 32 by the side walls bounding the immediate portion 35 of the slot 32.

The rear face of the platform 33 with respect to the clamp part 7 (i.e., the upper face in Figure 1) is provided with a groove 34 extending transversely of the arm 1 and in which the transverse extensions 29 are locatable when the clamp has been closed to the positions illustrated in Figure 4 and the pin 25 has been turned to its clamping position in which the transverse extensions 29 extend lengthwise of the groove 34 and at right angles to the length of the slot 32. The platform 33 is chamfered at 37. When the clamp is closed the inclined extension 36 of the clamp part 7 is parallel with the chamfered face 37 (as shown in Figure 4).

However, to effect locking of the clamp, as will hereinafter be explained, the clamp part 7 has to be overclosed. The inclined extension 36 and the chamfered face 37 form a pair of engageable stop faces, which when engaged limit the amount of over-tightening of the clamp to avoid damage to the clamp.

When the clamp has been locked to the position shown in Figure 4, the extension 36 of the clamp part 7 will extend into the box-like region 39 of the arm 1 and thus sideways movement of the clamp part 7 relatively to the arm 1 will be limited by one or other of the side edges of the extension 36 coming into engagement with the side walls of the box-like region 39. Thus if longitudinal load on the liners 8, 9 by the sub-conductor 40, clamped thereby, should be excessive, the extension 36 will engage one or other of the side walls of the box-like region 39 and so prevent excessive load on the liners 8, 9.

Before the clamp is to be used, the shank of the pin 25 is inserted through the slot 31 in the extension 36 of the clamp part 7 and then through the slot 32 in the platform 33 in the clamp part 6. The bifurcated ends of the pin 25 are then splayed apart to prevent the bulbous end portions 28 from passing back through the slot 32 and to locate those portions in the intermediate portion 35 of the slot 32. By turning the pin 25 about its longitudinal axis so that the transverse portions 29 will pass through the slot 32, the clamp member 7, when the hinge parts 20, 21 have been detached from each other, will hang freely down from the clamp member 6, assuming the latter is uppermost (as shown in Figure 2); but the head 27 of the pin will prevent the clamp member 7 from separating completely from the arm 1. The pin 25 can rock in the intermediate portion 35 of the slot 32 to enable the hinge to be disengaged. Also, for this purpose, the clamp member 7 can be slid in the longitudinal direction of the slot 31, relatively to the pin 25. The length of the shank of the pin 25 between the end portions 28 and the head 27 is sufficient to permit disengagement and re-engagement of the hinge parts 20, 21 and opening of the clamp parts 6 and 7 to an extent sufficient to enable the clamp to be removed from or placed around a sub-conductor 40.

When the clamp is to be clamped to a sub-conductor, such as 40, after the clamp arm 1 has been bolted to the spacer-damper body 2, the liner 8 in the clamp part 6 is placed around the sub-conductor 40 (as shown in Figure 2). The hinge is assembled by inserting the tongue 20 in the socket 21 and the clamp parts 6, 7 are closed together to place the liners 8, 9 around the subconductor 40. Then the pin 25 is pushed transversely of the slot 31 with the transverse extensions 29 aligned with the slot 32, until the transverse extensions 29, which form the latch member, have been passed through the platform 33. The pin is then turned through 90 and this will position the transverse extensions 29 in the groove 34, to clamp the clamp members 6, 7. The length of the shank of the pin 25 between the ends of the extensions 29 nearer to the head 27 and the head 27 is such that the extension 36 of the clamp member 7 will be substantially parallel with the chamfered face 37 of the clamp member 6 when the pin 25 is in its locked position and the conductor will be gripped between the liners 8 and 9 with a required predetermined force. As aforesaid, the provision of the chamfered stop face 37 prevents overtightening of the clamp and therefore prevents damage to the clamp. As the gripping force is predetermined by the length of the shank 26 of the pin 25, there is no requirement for continued turning of the pin, as in the case of a threaded bolt. The operator will know that the clamp has been correctly closed by observing the positions of the rib 30 of the pin which will then be at right angles to the slot 31, indicating that the transverse extension 29 will be located in the groove 34.

The steps to be taken in the installation of the clamp on the arm of a spacer-damper on a sub-conductor are as follows: 1. The sub-conductor 40 is wiped clean; 2. The pin 25 is turned to its release position and withdrawn until the end por tions 28 have engaged with the slot portion 35; 3. The clamp part 7 is disengaged at the hinge from the clamp part 6 and allowed to slide relatively to the pin and hang downward on the pin and thus remaining suspended from the arm 1, as shown in Figure 2; 4. The liner 8 in the clamp part 6 is placed on the conductor 40, as shown in Figure 2; 5. The clamp part 7 is engaged with the clamp part 6 at the hinge and is swung upwardly to engage the liner 9 with the sub-conductor through the position shown in Figure 3 to the position shown in Figure 4.

6. A compression tool, or manual compression, is used to effect the clamping force and the pin 25 is turned to the position shown in Figure 4 to clamp the two clamp parts 6, 7 together, the correct position of the rib 30 being observed.

7. The compression tool, where used, is then removed.

The clamp is therefore easier to use with an overhead sub-conductor of a bundle of sub-conductors than one having separated clamp parts and a separate locking bolt to be inserted therein and tightened to a required torque.

WHAT WE CLAIM IS: 1. A clamp to be engaged with an overhead electrical conductor, as defined herein, comprising a first clamp part having therein a first semi-cylindrical recess, a second clamp part having therein a second semi-cylindrical recess, a pair of interengageable and separable hinge-defining surfaces formed one on each of said clamp parts and which when interengaged one with the other define a hinge having an axis parallel with the axes of the recesses, thereby to permit the two clamp parts to be pivoted relatively of each other about the hinge axis to effect engagement of the two recesses coaxially around the conductor or to permit the clamp to be released therefrom, and a pin extending freely through an elongate aperture in one of said clamp parts at the side of the recess therein remote from the hinge surface, the pin having an enlarged end portion by which the pin is held from removal from the other of said clamp parts, the pin being relatively rotatable in said other part about the longitudinal axis of the pin, and a head remote from said enlarged end portion and engageable by the face of said one clamp part remote from said other clamp part, the length of the pin between said enlarged end portion and said head being sufficient to permit the two clamp parts to be pivoted away from one another about the hinge-defining surfaces to effect the release of the clamp from the conductor and to enable the hinge surfaces to be disengaged one from the other, the pin then acting to retain the two clamp parts from complete separation one from the other, the pin also having a latch member thereon extending transversely of the pin at a location intermediate said enlarged end portion and the head of the pin and arranged to pass through the aperture in said one clamp part and a corresponding aperture in said other clamp part when the pin has been turned about its longitudinal axis to align the latch member with the larger dimension of the aperture, the latch member serving to clamp the two parts together to grip the conductor therebetween after the two clamp parts have been hinged together and pivoted towards each other, the recesses have been positioned around the conductor, the latch member has been passed through the apertures in both clamp parts and the pin has been turned about its longitudinal axis until the latch member extends transversely of the apertures and bridges the sides of the aperture in said other clamp part to bear against the face of said other clamp part remote from said one clamp part.

2. A clamp as claimed in claim 1 in which the aperture in said one clamp part is a slot extending outwardly with respect to the recess in said one clamp part and transversely thereto.

3. A clamp as claimed in claim 2 in which the portion of said one clamp part defining the slot extends in the direction of clamping movement of said one clamp part towards said other clamp part along a line inclined at an acute angle to a tangent to a circular are struck from the hinge axis.

4. A clamp as claimed in claim 3 in which said portion of said one clamp part is shaped to extend, when the clamp parts have been clamped around the conductor, between a pair of stop faces to limit relative sideways movement of the clamp parts longitudinally of the conductor.

5. A clamp as claimed in any preceding claim in which the pin has a bulbous, bifurcated end portion remote from the head, the end portion being located in the aperture in said other clamp part, in which aperture said end portion is rotatable about the longitudinal axis of the pin and in which said end portion can be rocked transversely of the longitudinal axis of the pin, the pin being retained in the aperture by splaying apart the sides of the bulbous, bifurcated end portion thereof to form the aforesaid enlarged end portion.

6. A clamp as claimed in any preceding claim in which the latch member on the pin is of the shape of a barb having side faces extending at an acute angle to the longitudinal axis of the pin at each of a pair of diametrically-opposite positions, the latch member bearing against the said remote face of said other clamp part when the pin has been turned to its clamping position and the clamp parts have been pivoted together to grip the conductor therebetween.

7. A clamp as claimed in claim 6 in which the head of the pin has an outward, axiallyfacing rib which extends parallel to the crossline of the barb and thus the direction of the rib indicates whether the barb is in its unclamped or clamped position.

8. A clamp as claimed in any preceding claim in which the surfaces defining the hinge comprise a tongue extending from a first of the clamp parts and having a convex surface thereon and a socket on the second of the clamp parts, into which socket the tongue is insertable, the socket having a concave surface with which the convex surface on the tongue is engageable.

9. A clamp as claimed in any preceding claim in which the two clamp parts each have a stop face thereon, the two stop faces

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. position of the rib 30 being observed. 7. The compression tool, where used, is then removed. The clamp is therefore easier to use with an overhead sub-conductor of a bundle of sub-conductors than one having separated clamp parts and a separate locking bolt to be inserted therein and tightened to a required torque. WHAT WE CLAIM IS:

1. A clamp to be engaged with an overhead electrical conductor, as defined herein, comprising a first clamp part having therein a first semi-cylindrical recess, a second clamp part having therein a second semi-cylindrical recess, a pair of interengageable and separable hinge-defining surfaces formed one on each of said clamp parts and which when interengaged one with the other define a hinge having an axis parallel with the axes of the recesses, thereby to permit the two clamp parts to be pivoted relatively of each other about the hinge axis to effect engagement of the two recesses coaxially around the conductor or to permit the clamp to be released therefrom, and a pin extending freely through an elongate aperture in one of said clamp parts at the side of the recess therein remote from the hinge surface, the pin having an enlarged end portion by which the pin is held from removal from the other of said clamp parts, the pin being relatively rotatable in said other part about the longitudinal axis of the pin, and a head remote from said enlarged end portion and engageable by the face of said one clamp part remote from said other clamp part, the length of the pin between said enlarged end portion and said head being sufficient to permit the two clamp parts to be pivoted away from one another about the hinge-defining surfaces to effect the release of the clamp from the conductor and to enable the hinge surfaces to be disengaged one from the other, the pin then acting to retain the two clamp parts from complete separation one from the other, the pin also having a latch member thereon extending transversely of the pin at a location intermediate said enlarged end portion and the head of the pin and arranged to pass through the aperture in said one clamp part and a corresponding aperture in said other clamp part when the pin has been turned about its longitudinal axis to align the latch member with the larger dimension of the aperture, the latch member serving to clamp the two parts together to grip the conductor therebetween after the two clamp parts have been hinged together and pivoted towards each other, the recesses have been positioned around the conductor, the latch member has been passed through the apertures in both clamp parts and the pin has been turned about its longitudinal axis until the latch member extends transversely of the apertures and bridges the sides of the aperture in said other clamp part to bear against the face of said other clamp part remote from said one clamp part.

being engageable, one with the other, when the two clamp parts are pivotally closed together and locked by the pin.

10. A clamp as claimed in any preceding claim in which each recess accommodates a semi-cylindrical elastomeric liner, the two liners when closed together around the conductor co-operating to form a resiliently deformable tube in which the conductor is gripped.

11. A clamp as claimed in claim 10 in which each liner is detachable from the respective recess and has at least one circumferentially-extending rib or groove cooperable with a complementary groove or rib defined in the circumferential wall of the recess and at least one radially-extending tongue or recess co-operable with a complementary radially-extending recess or tongue in the circumferential wall of the recess.

12. A clamp as claimed in claim 10 in which each liner is permanently bonded to the circumferential wall of the respective recess.

13. A spacer-damper assembly for a bundle of sub-conductors of an overhead electricity transmission line, including a plurality of clamps in accordance with any preceding claim, there being one clamp for each sub-conductor and said other clamp part of each clamp constituting an arm of the spacer-damper assembly and being at the end thereof remote from the recess therein, a hole for receiving a pivot by which the arm is to be attached to a body of the spacerdamper assembly.

14. A spacer assembly for a bundle of two or more sub-conductors of an overhead electricity transmission line, including a clamp in accordance with any preceding claim 1-12, for clamping to each subconductor in each of which clamps said other clamp part is formed on a common member with at least one other like clamp part.

15. A clamp for gripping a sub-conductor of an overhead electricity transmission line constructed and arranged substantially as described herein with reference to and as shown in the accompanying drawings.