TABLE OF CONTENTS The concept of EMC applies not only to high frequency phenomena. A product must be compatible with its electromagnetic environment, and there is no limitation on the frequency range encompassed by that environment, nor on the modes of coupling with it. A universal requirement is that the product should be compatible with its power supply; that is, it must be adequately immune from variations in the power supply, and it must not itself cause such variations. This is necessary whether the supply is DC, AC 50Hz mains or some other system-specific description, but for the public AC mains there are a number of common requirements which apply under the umbrella of the EMC Directive and which are discussed here.
Harmonic components of the AC supply input current to an item of equipment arise from non-linearities of the load over a single cycle of the input voltage. The EMC Directive includes requirements for measuring harmonic emissions as embodied in IEC 61000-3-2 (EN 61000-3-2), which covers all electrical and electronic equipment with an input current up to 16A per phase. This has a sister standard (actually a technical report), IEC 61000-3-4, for higher-powered equipment up to 75A, which has been supplemented by a full international standard, IEC 61000-3-12. The generation and control of mains harmonics are discussed further in section 10.4 and the standards themselves are surveyed in section 4.5.1.
Although the harmonic frequency range under consideration extends only up to 2kHz (the 40th harmonic of...
