Electromagnetic interference suppression system for electrical equipment

摘要

Method and apparatus for suppressing differential and common mode conducted electromagnetic interference emission in electrical equipment powered from a grounded A.C. line source without creation of a shock hazard. Differential mode interference is suppressed by connecting a capacitor across the power lines and common mode interference is suppressed by an inductor inserted in the ground lead, both positioned within the equipment case or housing. The capacitor and inductor can have substantially fixed values for a wide range of equipment. In the preferred embodiment, the inductor is constructed by winding a few turns of the ground lead itself through a high permeability, ferrite toroid positioned within the case or housing.