British Rail experience with electrical insulation

British Rail Research has a wide range of power electrical equipment on vehicles and on trackside, such as motors, transformers, switchgear, cables, overhead and third rail lines. Much of the equipment, and the electrical insulation, is subjected to heavy pollution, vibration and shocks from repeated flashovers. Here, the author describes British Rail´s experiences with electrical insulation. He details how most insulation performs well, but some failures have been precipitated by a combination of mechanical and environmental stresses