Improvement to the booster transformer/return conductor method of suppressing 50 Hz interference from a.c.-electrified railway systems

Improvements, which could result in a reduction of the cost of signalling and telecommunication cables, are theoretically obtainable in the suppression of 50 Hz interference from a.c.-electrified railway systems using booster transformers and return conductors. A fundamental improvement results by increasing the height of the return conductors. A combination of return conductor only and return conductor/booster transformer suppression gives a method which, theoretically, is particularly attractive for 4-track systems; an initial practical test has shown reasonable agreement between theory and practice.