The design of overhead electric lines for improved reliability

Traditional overhead line design in the UK has involved calculation to show compliance with requirements which guarantee stress limitations in components under specific loading conditions. The approach is described mathematically as deterministic and the minimum requirements which limit stress (the Factor of Safety) and the loading conditions under which these must be met have been uniform across the country and have been set by statute. The author describes the production of a new national standard for high voltage single circuit wood pole lines which adopts a matrix approach to design, matching site weather parameters with component capabilities, to specify line designs based on common components and arrangements for use throughout the UK. The author focuses attention on some of the more important aspects of the performance base now being considered and upon the flexibility inherent in and the possible future usefulness of this matrix approach