Harmonic distortion caused by suburban and underground rolling stock with DC motors

The paper presents the problem of disturbances caused by the converters of electric traction vehicles with DC motors. Although these type of rolling stock have been used since the 1970s, the problem is still vital, especially in countries without experience with modern electric traction. When a project to introduce new types of rolling stock in a suburban railway or underground line is carried out, analyses have to be done in order to estimate the electromagnetic disturbances which could be caused by the vehicles' converters, especially when the existing signalling and control system is of an old type. The authors discuss the problems of harmonic disturbance and then discuss the PC-NAP simulation tool used for simulating the harmonic disturbances in the whole traction system.