Low frequency and radio frequency electromagnetic compatibility for rapid transit railways

The authors begin by explaining how EMC with signalling equipment first became identified as a major issue for rapid transit railway traction engineers when variable frequency chopper power electronic controllers were introduced due to adverse interaction with signalling systems. They explain the nature of the problem and the early steps taken to solve it by traction engineers, principally fixed frequency operation. Evolution of the signalling equipment in relation to this problem is explained together with design rules that still need to be applied to chopper traction drives even with modern signalling equipment. The introduction of inverter drives has created a similar situation to that for the early chopper drives. The authors show this time, the EMC factor has been solved despite the variation in frequency of operation inherent in a variable frequency variable voltage inverter drive. Finally, they introduce the new EMC problems being faced with radio frequency equipment and the inadequacy of existing European standards