scope:

NEN-EN 50121-4 applies to signalling and telecommunication apparatus that is installed inside the railway environment. Signalling and telecommunication apparatus mounted in vehicles is covered by EN 50121-3-2:2015, signalling and telecommunication apparatus installed inside the substation and connected to substation equipment is covered by EN 50121-5:2015. This European Standard specifies limits for emission and immunity and provides performance criteria for signalling and telecommunications (S&T) apparatus (including power supply systems belonging to S&T) which may interfere with other apparatus inside the railway environment, or increase the total emissions for the railway environment and so risk causing Electro-Magnetic Interference (EMI) to apparatus outside the railway system. Apparatus which complies with the emission levels of EN 61000-6-4 will meet the emission requirements of this standard provided that emissions from any DC power port are within the emissions limits specified for AC power ports. The immunity levels given in this standard apply for - vital equipment such as interlocking or command and control, - apparatus inside the 3 m zone, - ports of apparatus inside the 10 m zone with connection inside the 3 m zone, - ports of apparatus inside the 10 m zone with cable length > 30 m.