Field trial of carbon composite core covered conductor system

摘要

Bare Single Wire Earth Return (SWER) conductors have been associated with a number of fire starts which have resulted in a large loss of life and property. This paper presents a field trial demonstration of an alternative to traditional bare conductors aimed at reducing the potential fire start risk. The electrification of remote and rural areas via the SWER system was possible due to the low capital cost (primarily due to long spans and simple pole top infrastructure), ease of installation (simple stringing techniques) and relatively simple support infrastructure required (transformers, fuses, insulators). The system initially developed in New Zealand found early acceptance in Australia where there is now over 200,000km installed. The 22 and 33kV SWER systems are also located in the Americas, Africa, and Asia. Typically the networks utilise traditional galvanised or Alclad steel wire constructions such as SC/AC 3/2.75mm. With such conductors, long spans (400 to 800m) through remotely populated, farming, forest, and scrub vegetation are not uncommon for the SWER network. The wide variety of vegetation, wildlife and weather interactions across the remote and rural network pose a number and variety of risks. The potential for fire starts is one such risk. The main identified risks associated with bare conductors are from broken energised conductors falling into combustible vegetation; trees coming into contact with energised conductors and wildlife electrocutions at pole tops. Increasing the strength of the conductor and applying a covering address these possibilities. The ability to utilise the strength to weight properties of composite materials coupled with an abrasion resistant covering allows the opportunity to utilise the existing pole infrastructure and maintain sag clearances. Pole top fittings and connections designed for the conductor, environment and interconnection with the existing infrastructure are required for the transition from bare to covered conductor systems. The conductor, fittings, and installation experience gained from a field trial in a high fire danger region of Victoria Australia are outlined in more detail in this paper.