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    Electromagnetic Compatibility (EMC)

    Summary

    the EMC Directive differs from most other directives in that its primary requirement is protection of the electromagnetic spectrum rather then safety of the equipment.

    The vast majority of electrical products must comply, whether battery or mains powered. Exceptions include – but are not limited to – components and sub assemblies with no intrinsic function and products already covered by other directives (medical, military, automotive, some agricultural, transmitting and communications equipment).

    The Directive requires that products must not emit unwanted electromagnetic pollution (interference) and must be immune to a normal level of interference. Compliance with these requirements is usually demonstrated by testing to harmonized standards but testing is not mandatory and a manufacturer may choose provide a technical assessment for compliance as an alternative.

     

    Scope

    The Directive is one of the widest in its application and all electrical products must comply whether they are mains or battery powered. The only exceptions are for components or sub assemblies with no intrinsic function (i.e. their use cannot be defined unless they are combined with other components) and certain electrical products and systems which are already covered by other directives. Examples of components which do not need to comply are plugs and sockets, capacitors, resistors and integrated circuits. More complex sub-assemblies such as power supplies, micro-controllers and cards for PC’s do have to comply. As a rule of thumb, if it possible to make meaningful EMC tests on a product then it needs to comply and be CE marked accordingly, unless it is covered by one of the specific exclusions.

    Products covered by a more specific directive which also contains EMC performance requirements are excluded from the scope of 2004/108/EC. For example medical devices, military equipment, road going vehicles and certain agricultural equipment are all excluded from the scope of the EMC Directive itself because they are subject to more specific directives containing equivalent EMC provisions.

    Fixed installations are excluded from some of the requirements of the Directive but must still meet the basic protection requirements as well as the requirements for technical documentation.

    Most communications apparatus is excluded from the scope of the EMC Directive, either wholly or in part, but instead comes under the scope of the R&TTE Directive.

     

    Requirements

    In essence the requirements of the Directive are very simple - it basically states that products must not emit unwanted electromagnetic pollution (interference) and, because there is a certain amount of electromagnetic pollution in the environment, that products must be immune to a reasonable amount of interference. The Directive itself gives no figures or guidelines on what the required level of emissions or immunity are, nor does it state the frequency band limits. This interpretation of the Directive's requirements is left to the standards that are used to demonstrate compliance with the Directive.

    In addition to these essential protection requirements, the Directive requires the manufacturer to compile technical documentation which shows that the essential requirements have been met, to put the CE logo on the product and to complete a Declaration of Conformity. Manufacturers must also identify themselves on the equipment and ensure that, where necessary, instructions are supplied to ensure that the use of the equipment meets the essential protection requirements.