Electrical Interference from Thyristor-Controlled DC Propulsion System of a Transit Car

Analysis and measurement of radiated and conducted electromagnetic interferences were performed on a transit car equipped with chopper-controlled dc propulsion system. The measured values of the radiated interference showed significant disagreement with the calculated values. It was determined from the analysis of the measured data that the voltage drop caused by the dc propulsion-current harmonics contributed to the discrepancies. Extensive tests on the ¾-mi (1.2-km) long third-rail fed test track at the General Electric plant in Erie, PA, showed that the interference levels generated from the chopper-controlled propulsion equipment are acceptable. However, it is felt that the existing and impending electromagnetic compatibility (EMC) standards are, in some instances, neither technically sound nor realistic. Suggestions are made for the improvements of standards and measurement procedures.