Radiated emission measurements for MRVC II-electrical multiple unit (EMU) as per BS EN 50121-3-1:2006: — A case study

The Suburban trains (Electo-Mechanical Unit also abbreviated as EMU) are in service catering to Mumbai suburban transport requirements for last couple of decades. The system was running on electric traction voltage of 11 kV A.C. supply line for all these years. The development authority, Mumbai Rail Vikas Nigam (MRVC) have planned to transfer the train operations on 25 kV D.C. supply as against earlier A.C. supply. The modern rail system comprises of lot of electronics embedded into it. Also, there is a lot of communication and signaling systems in the vicinity of the rolling stock, which may or may not be related to railway operations. The rolling stock is also prone to EMI related problems as encountered by any other electronic equipment due to this kind of environment. The large number of urban population uses these transport services, they need to be operated taking into consideration all safety precautions inclusive of EMI compliance. The EMI related incidence could create a catastrophic situation wherein lot of users could get affected. In addition to the routine measurements, the measurements relevant to human physiology (passenger wearing a pacemaker in the heart) is also a cause of concern. In the past, many EMI incidences especially related to signaling system failure have been reported elsewhere. The product specific standard EN 50121-X series is available for which, not only the rolling stock but the whole railway system encompassing Sub Stations, Signaling systems etc. needs to be complied with EMI norms. The radiated emission measurement to be conducted for rolling stock is challenging preposition as stated on rolling stock measurements for Monorail [1]. Due to high speed of the rolling stock very short time of the order of 6-9 seconds are is available for recording a scan for the entire frequency range. To reduce the scan time we have used the higher resolution bandwidth (RBW) permitted by the standard. During the first exercise, the rolling stock could not comply with the specified limit at low frequency. As per standard's recommendation, if the EUT (rolling stock) complies by repeating the same measurement at other location then the compliance can be declared [2] [3]. Accordingly, the repeat measurement was planned and carried out at distance of around 250 meters away from earlier location. In addition one capacitor bank unit installed near the track was also switched off. The repeat measurement so performed complied with the requisite limit line as per standard document EN 50121-2. In this paper, we have presented the results of the Radiated Emission measurements conducted for Mumbai Suburban train under the MRVC project.