If the operation of electronic components switching scheme to reduce congestion and losses (in power converters in general and switching power supplies in particular), it also generates electromagnetic type of pollution in its immediate environment. Power Electronics for Industry and Transport, Volume 4 is devoted to electromagnetic compatibility. It presents the sources of disturbance and the square wave signal, spectral modeling generic perturbation. Disturbances propagation mechanisms called "lumped" by couplings such as a common impedance, a parasitic capacitance or a mutual and "distributed constant", for which the spatial-temporal character must be taken into account, are also covered. This book also provides spectral analysis among other items that contain inequality Heisenberg-Gabor, very useful for understanding the spread spectrum PWM type signals.