This European Standard applies to signalling and telecommunication apparatus that is installed inside the railway environment. Signalling and telecommunication apparatus mounted in vehicles is covered by EN 50121-3-2:2016, signalling and telecommunication apparatus installed inside the substation and connected to substation equipment is covered by EN 50121-5:2016. 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. The requirements specified 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 c
