Telecommunication systems in relation to 50Hz a.c. electric traction

The current methods for reducing the effects of inductive interference in lineside telecommunication cables on railways, electrified at industrial frequency, are briefly summarised. The methods employed by British Railways for calculating induced longitudinal voltages in cables are outlined, together with standard calculated values in tabular form. The degree of electromagnetic screening which can be obtained by the use of high-conductivity cable sheaths and steel-tape armouring is illustrated. The effects of the method of traction-current control in motive-power units, with respect to the generation of noise in cables, are also discussed.