GB2189655A

GB2189655A - Support for supporting overhead electrical cables

Info

Publication number: GB2189655A
Application number: GB08609757A
Authority: GB
Inventors: William Percival Baker; David Voas
Original assignee: Electricity Council
Current assignee: Electricity Council
Priority date: 1986-04-22
Filing date: 1986-04-22
Publication date: 1987-10-28
Also published as: EP0243175A1; GB8609757D0

Description

GB2189655A 1 SPECIFICATION With a support according to this invention the

insulating members, which can be in the Support for supporting overhead electrical form of silicone rubber rings, serve to increase cables the local radius of curvature at the peripheries 70 of the flanges, and thus serve, in use, to de This invention relates to a support for sup- crease the local stresses that occur at these porting overhead electrical cables. positions, whereby the conditions leading to High voltage, for example 132kV, overhead the production of an enveloping charged at electrical cables are often supported by sup- mosphere about the support are avoided.

ports mounted on cross-arms carried by a 75 The radius of curvature provided by the in tower or wooden pole, each support compris- sulating members is determined by the need ing a body of electrically insulating material to increase the radius of curvature of the providing a plurality of flanges arranged in flanges sufficiently to avoid local high spaced parallel planes. stresses, while ensuring that sufficient spacing Supports of such a shape are used since 80 is maintained between adjacent insulating they provide a long creepage path over their members to prevent flash- over occuring under surface between their ends thus providing rainy atmospheric conditions.

good protection against flash-over between a This invention will now be described by supported cable and the supporting tower dur- way of example with reference to the draw- ing adverse atmospheric conditions. 85 ing, in which:

Such supports have been made of porcelain Figure 1 shows three known forms of sup material, but recently they have been made of port to which the invention can be applied; polymeric material since the greater strength Figure 2 is a side view, partly in section, of of such material enables the flanges, known part of a support according to the invention; as sheds, to be made thinner, thus enabling a 90 and greater number of flanges to be provided in a Figure 3 shows a detail of the support of support of a given length. Further, under nor- Fig. 2.

mal dry or rainy atmospheric conditions the Fig. 1 shows three supports each compris modification to the electric field surrounding a ing a body 1, 2 or 3 of electrically insulating support in use, caused by the flanges, is 95 material, such as polymeric material, providing much smaller for supports made of polymeric a plurality of circular flanges 10 arranged in material than for supports made of porcelain spaced parallel planes, and having at one end material. 4 a fitting for connection to a cross-arm car However, it has been discovered that under ried by a tower or wooden pole and at the certain atmospheric conditions, for example 100 other end 5 a fitting for connection to a cable low temperature, low wind speed, heavy mist, to be supported. The body 1 provides flanges and an upward air flow around a support, the 10 all of the same diameter and lying in whole surface of the support, and not just the planes inclined to the longitudinal axis of the upwardly facing surfaces thereof as is normal, support; the body 2 provides flanges 10 of becomes sufficiently wetted to be significantly 105 alternating relatively large and relatively small electrically conductive. diameter lying in planes perpendicular to the This is particularly so if the surface of the longitudinal axis of the support; the body 3 support has a coating of an ionisable material, provides flanges 10 of alternating relatively such as salt from the atmosphere, thereon. large and relatively small diameter lying in When a support is so wetted and thus elec- 110 planes inclined to the longitudinal axis of the trically conductive, the surrounding electric support.

field can be modified to such an extent that Figs. 2 and 3 show a support with a body local high stresses arise at the peripheries of 1 as shown in Fig. 1, with which a plurality of the flanges, these giving rise to the ejection of individual insulating members 20 in the form charged water particles from the peripheries. If 115 of circular cross- section silicone rubber rings, the surrounding atmosphere is sufficiently are mounted about the peripheries of respec damp and the wind speed sufficiently low the tive ones of the flanges 10, the members 20 supports can become enveloped in a charged being sized to increase the radius of curvature atmosphere which can result in flash-over oc- of the peripheries of the flanges 10. As curring. 120 shown in Fig. 3, each member 20 is formed According to this invention there is provided with an inwardly open groove 21 which rea support for supporting overhead electrical ceives a peripheral edge portion of the associ cables, comprising a body of electrically insu- ated flange 10 whereby the member 20 is lating material providing a plurality of flanges retained on the flange 10. The depth of the arranged in spaced parallel planes, and a plu- 125 groove 21 is the maximum possible compat rality of individual insulating members each ible with retaining sufficient strength for the mounted about the periphery of a respective member 20. A self-vulcanising material is pro one of said flanges and being sized to in- vided in the groove 21 in order to fill any crease the radius of curvature of the periphery indentations in the surface of the flange 10 of said one flange. 130 caused, for example, by weathering and/or 2 GB2189655A 2 discharge activity.

Claims

1. A support for supporting overhead elec- trical cables, comprising a body of electrically insulating material providing a plurality of flanges arranged in spaced parallel planes, and a plurality of individual insulating members each mounted about the periphery of a re- spective one of said flanges and being sized to increase the radius of curvature of the periphery of said one flange.

2. A support as claimed in Claim 1, in which the body is of polymeric material.

3. A support as claimed in Claim 1 or Claim 2, in which the insulating members are rubber rings.

4. A support as claimed in Claim 3, in which each rubber ring is formed wiht a groove to receive a peripheral edge portion of the associated flange.

5. A support as claimed in Claim 4, in which the groove contains a selfvulcanising material.

6. A support for supporting overhead electrical cables, substantially as hereinbefore described with reference to the drawing.

Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd, Dd 8991685, 1987. Published at The Patent Office, 25 Southampton Buildings, London, WC2A 'I AY, from which copies may be obtained.

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