Full Time Domain EMI Measurement System Applied to Railway Emissions According to IEC 62236-3-1/EN 50121-3-1 Standards

This paper studies the advantages of applying time-domain based instrumentation to conduct electromagnetic interference emissions from rolling-stock. In IEC 62236-3-1 or EN 50121-3-1 standards, it is mandatory to measure the railway vehicle in static and in-motion conditions. When conventional frequency sweep instrumentation is employed, difficulties regarding ambient noise variation and the short-duration of worst-case emission modes take place. In Annex B of the standard, a test procedure is described to acquire the worst-case EMI, however, as it is explained at the paper the effective measured time at each frequency is only 0.08 ms in some frequency bands. Hence, multiple movements of the vehicle are needed increasing the uncertainty of the measured source and making difficult to distinguish vehicle EMI from background noise interference. To solve this problem, a Full-TDEMI measurement system is proposed with the availability to increase the effective measured time, reduced the ambient noise variation, the usage of multiple antennas at the same time and the possibility to discard transient interference that should not be evaluated. At the end of the paper, measurements carried out with the time-domain system are shown demonstrating the effectivity of the methodology.