Electric traction for intercity trains

With the decision in 1955 to adopt 25 kV 50 Hz as the supply voltage for overhead electrification on British Railways came the requirement for locomotives to pull passenger and freight trains. The first 100 locomotives introduced in 1960 were originally numbered in the E 3000 range and later became Classes 81 and 85. These were followed by a batch of 100 Class 86 locomotives which were introduced in 1965 and 36 Class 87 locomotives which entered service in 1973. Next came the 3 APT prototype trains which saw very limited service between 1980 and 1984 and in 1987 and 1988 came the first deliveries of Class 89, 90 and Class 91 locomotives. Channel Tunnel trains using 3-phase traction motors are being specified for through services between London, Paris and Brussels. The author discusses each of these different forms of traction.<>