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Johnson Mariapon MIEAust, CPEng, RPEQ, Assoc.MIRSE

Aurizon

As contemporary railway signalling adopts more and more sophisticated electronics, incorporating communication subsystems like network switches, modems and diagnostics for overall train control, the need for high performance power supplies to feed these items is a paramount. The sensitive Signalling & Telecommunications (S&T) devices cannot even tolerate a momentary break in the power supply because these breaks affect its normal functioning and can reduce its designated life expectancy. This tutorial paper discusses techniques for designing a reliable power supply for signalling and communication systems using modern power equipment. Details on current electrical safety practices specific to S&T are also provided. In most signalling training, subjects discuss the signalling design and general power supply concept but do not focus largely on the unearthed power supply systems adopted for railways (Floating Supply) and requirements for feeding the signalling equipment in a traction electricity environment. This paper addresses this gap by exploring, explaining and outlining the floating signalling power supplies and the associated usage of Earth Leakage Detectors (ELD) in signalling power supplies in detail. This paper also emphasizes the application of AS/NZS 3000:2007 standards in signalling power design.