This article gives brief account of conductor accessories, insulator hardware and power clamps and connectors suitable for HTLS conductor
 Due to right of way problem in the entire country, emphasis is on transferring big chunk of power through the least physical corridor. To achieve this, the conductor surface temperature has to be taken to more than 100C. The normal ACSR conductor loses its electrical and mechanical properties beyond 90C. It is therefore necessary to use high temperature low sag (HTLS) conductors.
HTLS conductors can operate up to the temperature 250C and therefore can transmit large quantity of power. It is worth noting that the ampacity of the conductor increases as the temperature is elevated.
For operating the conductors on very high temperatures, metallurgical changes in the conducting outer layers as well as the centre core has to be done. Annealing of the conducting material and coating the steel core with heat resistant material such as Galfan or using carbon core, affords high ampacity.
When the surface temperature of the conductor (HTLS) is elevated, the conductor accessories, insulator hardware and power clamps and connectors suitable for ACSR conductor cannot be used for HTLS conductor. Therefore, a technological development had to have high temperature hardware and fittings designed and developed for the manufacture. Further, thorough testing of the connectors as per relevant IEC standard is carried out. This article gives brief account of such conductor accessories, insulator hardware and power clamps and connectors suitable for HTLS conductor.
Benefits of HTLS conductorsHTLS conductors deliver higher amount of current or power at the elevated temperatures. The advantage of use of HTLS conductor is that when they are used on the towers designed for ACSR conductors, no major changes in the tower structures are required.
Even the HTLS conductors sag less and therefore afford higher ground clearance, when used on the existing lines. If HTLS conductors are used on the new line, HTLS conductors can allow higher spans and thus reduce number of towers along the route.
The weights and other mechanical properties of HTLS conductors are comparable with those of ACSR conductor. The Table 1 will give a comparative idea of HTLS conductors and Table 2 gives technical parameter of ACSS LARK conductor.
Details of HTLS conductors Before going to the subject, design and development of conductor fittings for high ampacity, high temperature low sag conductor, it is necessary to see what HTLS conductor is and how it differs in properties from commonly used conductors like ACSR and AAAC.
The conductors ACSR and AAAC are having maximum thermal rating of 90C. This means, in summer season when maximum ambient temperature is about 47-48C, the available scope to raise the temperature of these conductors above the ambient temperature is by 45C, which further limits the continuous current rating for these conductors, to satisfy this condition of maximum thermal limit of 90C.
To overcome the problem of this low thermal limit of 90C of ACSR and AAAC conductors, new conductors of high thermal rating of 200C, but with about same cross sectional area and same sag at the high thermal rating are invented, which are having continuous current rating of about double the current rating of equivalent size ACSR/AAAC conductor, but at high temperature of 180 to 200C.
There are a number of new High Temperature Low Sag (HTLS) conductors in the market designed to operate at temperatures of 200C and more. This is well above the normally accepted maximum operating temperature of 90C, allowed for the standard AAAC and ACSR conductors.
These new conductors still employ aluminium as the main current conducting medium. They have a core material inside the aluminium that provides high mechanical strength with a low coefficient of thermal expansion.
This internal core material is the main difference between conductors supplied by the various manufacturers. The new conductors are capable of carrying as much as two times the current, compared to that carried by AAAC and ACSR conductors of similar diameters without increase in the sag.
Limited experience indicates that the new conductors perform as advertised. They tend to cost two times or even more, than standard conductors to purchase and install.
Some require special handling and equipment for installation and maintenance.

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This article gives brief account of conductor accessories, insulator hardware and power clamps and connectors suitable for HTLS conductor
 Due to right of way problem in the entire country, emphasis is on transferring big chunk of power through the least physical corridor. To achieve this, the conductor surface temperature has to be taken to more than 100C. The normal ACSR conductor loses its electrical and mechanical properties beyond 90C. It is therefore necessary to use high temperature low sag (HTLS) conductors.
HTLS conductors can operate up to the temperature 250C and therefore can transmit large quantity of power. It is worth noting that the ampacity of the conductor increases as the temperature is elevated.
For operating the conductors on very high temperatures, metallurgical changes in the conducting outer layers as well as the centre core has to be done. Annealing of the conducting material and coating the steel core with heat resistant material such as Galfan or using carbon core, affords high ampacity.
When the surface temperature of the conductor (HTLS) is elevated, the conductor accessories, insulator hardware and power clamps and connectors suitable for ACSR conductor cannot be used for HTLS conductor. Therefore, a technological development had to have high temperature hardware and fittings designed and developed for the manufacture. Further, thorough testing of the connectors as per relevant IEC standard is carried out. This article gives brief account of such conductor accessories, insulator hardware and power clamps and connectors suitable for HTLS conductor.
Benefits of HTLS conductorsHTLS conductors deliver higher amount of current or power at the elevated temperatures. The advantage of use of HTLS conductor is that when they are used on the towers designed for ACSR conductors, no major changes in the tower structures are required.
Even the HTLS conductors sag less and therefore afford higher ground clearance, when used on the existing lines. If HTLS conductors are used on the new line, HTLS conductors can allow higher spans and thus reduce number of towers along the route.
The weights and other mechanical properties of HTLS conductors are comparable with those of ACSR conductor. The Table 1 will give a comparative idea of HTLS conductors and Table 2 gives technical parameter of ACSS LARK conductor.
Details of HTLS conductors Before going to the subject, design and development of conductor fittings for high ampacity, high temperature low sag conductor, it is necessary to see what HTLS conductor is and how it differs in properties from commonly used conductors like ACSR and AAAC.
The conductors ACSR and AAAC are having maximum thermal rating of 90C. This means, in summer season when maximum ambient temperature is about 47-48C, the available scope to raise the temperature of these conductors above the ambient temperature is by 45C, which further limits the continuous current rating for these conductors, to satisfy this condition of maximum thermal limit of 90C.
To overcome the problem of this low thermal limit of 90C of ACSR and AAAC conductors, new conductors of high thermal rating of 200C, but with about same cross sectional area and same sag at the high thermal rating are invented, which are having continuous current rating of about double the current rating of equivalent size ACSR/AAAC conductor, but at high temperature of 180 to 200C.
There are a number of new High Temperature Low Sag (HTLS) conductors in the market designed to operate at temperatures of 200C and more. This is well above the normally accepted maximum operating temperature of 90C, allowed for the standard AAAC and ACSR conductors.
These new conductors still employ aluminium as the main current conducting medium. They have a core material inside the aluminium that provides high mechanical strength with a low coefficient of thermal expansion.
This internal core material is the main difference between conductors supplied by the various manufacturers. The new conductors are capable of carrying as much as two times the current, compared to that carried by AAAC and ACSR conductors of similar diameters without increase in the sag.
Limited experience indicates that the new conductors perform as advertised. They tend to cost two times or even more, than standard conductors to purchase and install.
Some require special handling and equipment for installation and maintenance.

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