Abstract
Accurate and comprehensive methods for the assessment of radiated electromagnetic emissions in modern electric transportation systems are a necessity. The characteristics and susceptibility of modern victim signaling and communication radio services, operating within and outside the right-of-way, require an update of the measurement methods integrating or replacing the swept frequency technique with time domain approaches. Applicable standards are the EN 50121 (equivalent to the IEC 62236) and Urban Mass Transport Association (UMTA) with additional specifications from project contracts. This work discusses the standardized methods and settings, and the representative operating conditions, highlighting areas where improvements are possible and opportune (statistical characterization of measurement results, identification and distinction of emissions and line resonances, and narrowband and broadband phenomena). In particular for the Electromagnetic Compatibility (EMC) assessment with new Digital Communication Systems, the characterization of time distribution of spectral properties is discussed, e.g., by means of Amplitude Probability Distribution and including time distribution information. The problem of determination of site and setup uncertainty and repeatability is also discussed, observing on one hand the lack of clear indications in standards and, on the other hand, the non-ideality and intrinsic variability of measurement conditions (e.g., rolling stock operating conditions, synchronization issues, and electric arc intermittence).
Highlights
IntroductionElectrified transportation systems may represent a significant source of radiated electromagnetic emissions with peculiar mechanisms of emissions [1,2,3,4,5,6], considering disturbance to both circuits and services within the right-of-way [7,8,9,10,11,12,13,14,15], and more generally to the “outside world” [16,17]
(4.5) Such an approach to uncertainty would allow the evaluation of repeatability and reproducibility, establishing minimum requirements for site selection, beyond simple criteria based on distance from conductive elements and line discontinuities
Standards used for the measurement of radiated emissions of electric transportation systems and rolling stock have been considered: EN 50121-2, EN 50121-3-1, and Urban Mass Transport Association (UMTA)
Summary
Electrified transportation systems may represent a significant source of radiated electromagnetic emissions with peculiar mechanisms of emissions [1,2,3,4,5,6], considering disturbance to both circuits and services within the right-of-way [7,8,9,10,11,12,13,14,15], and more generally to the “outside world” [16,17]. As well as substations, see a widespread use of power conversion devices [29,30], with common-mode and radiated emissions shifted to higher frequency by the use of faster semiconductors They are the first victim environment for their own emissions interacting and possibly affecting the modern signaling, control, and communication systems, based on a wide range of known (e.g., GSM (the Global System for Mobile Communication), Wi-Fi) and innovative (e.g., CBTC, that stands for Communications-Based Train Control) protocols. This work focuses on methods and relevant factors for complete, accurate, and repeatable measurements to assess rolling stock and line radiated emissions in view of the characteristics of the potential victims. To guide the reader through the discussion and the relevant outcomes, the main facts and conclusions are reported in the “synthesis and highlights” subsection as a list of the major points, related methods, and suggested precautions and improvements
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