EMC commissioning and safety certification of AC rail transit vehicles - US experience

With the introduction of AC rail vehicles in the US, the same EMI/EMC methodology could be applied as was previously applied to DC systems. Of course, new analyses of an AC vehicle as an EMI interference source had to be developed by the propulsion system designer, but the interface equivalent circuit modelling of vehicle, traction supply network, and signalling system remained unchanged. The suggested test procedures for measurement of emissions and susceptibility were also generally applicable. Based on US experience, the following EMC issues and concerns should be noted: cab signal interference; undervehicle inductive emissions; vehicle input impedance; EMI monitoring/limit checking.