Evaluation of plastics insulators for use on British Railways 25 kV overhead line electrification

Plastics insulators based on resin-bonded fibre rods have been in use on British Railways for 20 years. This paper summarises the performance of these insulators and indicates where weaknesses have been found in materials and design. Accelerated test techniques are described which have been used to evaluate improvements in these areas, and service experience with new insulators is reported. The prospects for wider use of plastics insulators on railway overhead-line electrification are outlined.