Guidelines for Application of the EMC Directive

Guidelines concerning the application of the EMC Directive have been prepared by Directorate General III (Industry) of the Commission in collaboration with a group of government experts from member states, representatives from European standardization bodies and the Association of Competent Bodies, as well as representatives from European industry. These guidelines, which replace an earlier report published in October 1993, open up new possibilities for showing compliance within the requirements of the EMC Directive. This article gives a summary of the essential new issues generated by the guidelines.

The guidelines initially state that the main objective of the EMC Directive is to guarantee the free movement of apparatus within the European Economic Area (EEA). The report further states that the objective includes the creation of an acceptable electromagnetic environment in the EEA territory, referring to a harmonized and acceptable level of protection as requested in the directive.

The EMC Directive, Article 1.4, defines electromagnetic capability as the ability of an electrical and electronic appliance, equipment, or installation containing electrical and/or electronic components to function satisfactorily in its electromagnetic environment (immunity requirement) without introducing intolerable electromagnetic disturbances to anything in that environment (emission requirement).

The emission requirement concerns limitation of generated electromagnetic disturbances like noise and unwanted signals (i.e., spurious emissions). Concerning signals wanted and required for the use of a certain apparatus, they may be accepted as long as they are kept within certain frequency bands, such as the emission of radio-transmitting equipment that is within the required bandwidth and admissible radiated power. The immunity requirement means the ability to perform satisfactorily against the performance criteria for the apparatus in the presence of an electromagnetic disturbance. The aim of the protection requirement is the function and not the quality of an apparatus. Furthermore, the protection requirement does not guarantee absolute protection concerning emission and immunity.

The manufacturer's EMC analysis, helped as appropriate by the relevant harmonized standards and other technical knowledge, will determine the action to be taken. The directive lays down protection requirements and procedures under which the manufacturer may assess the apparatus against these requirements or may have it assessed by third parties. The manufacturer has sole and ultimate responsibility for the conformity of the apparatus to the EMC Directive as well as other applicable directives. Both the design and construction of the apparatus must be understood to be able to certify such conformity in respect to all applicable provisions and requirements of relevant directives.

The EMC Directive applies to apparatus that is liable to cause electromagnetic disturbances or that may have its normal operation affected by such disturbances. In this context, passive-EM equipment is excluded from the scope of the directive when used as intended. An example of such equipment, regarded as electromagnetically passive, is an apparatus that, without any user intervention, does not create or produce any switching or oscillation of current or voltage and is not affected by electromagnetic disturbances (i.e., batteries, cable accessories, or equipment containing only resistive loads without any automatic switching devices).

The expected level of protection must be proportional to the objectives pursued. As an example, the guidelines mention an electronic greeting card playing melodies, which is not expected to be immune to electromagnetic disturbances outside the ones for which it has been designed.

Although it should in principle be considered as within the scope of the directive, certain types of apparatus can be considered as exempt if both of the following criteria are fulfilled:

Other exemptions concern equipment that produce only transitory disturbances of very short duration during clearing of a short-circuit or abnormal situation in a circuit and that do not include electronic components that are EM active (e.g., fuses, circuit breakers, and manual switches).

The guidelines explicitly exclude quartz wristwatches and filament lamps (bulbs) from the scope of the directive.

The EMC Directive primarily covers new apparatus manufactured within the EEA and new or used apparatus imported from a third country when the apparatus is placed or taken into service on the EEA market. Since the protection requirements concern an apparatus, equipment, or installation when operated as intended, any product falling under the scope of the directive must include instructions for use (operating and installation manual).

The EMC Directive concerns electrical/electronic apparatus as defined in Article 1.1. It contains no explicit provisions on components, subassemblies, systems, or installations. A major part of the report, therefore, concerns the application of the EMC Directive to components, finished products, systems, and installations.

A component placed on the market for distribution or use as a single commercial unit is considered equivalent to apparatus if it has a direct function. This is defined as any function of the component itself that fulfills the intended use specified by the manufacturer in the instruction for use of an end-user. This function has to be available without further adjustment or connections other than simple ones, which can be performed by any person not fully aware of the EMC implications. The instructions for use of such direct-function components must be clear in these respects, so that the user can follow them without causing an EMC problem.

Examples of components with a direct function are

A finished product is any device, component, or unit of equipment that has a direct function, a cabinet of its own, and, if applicable, ports and connections intended for end-users. It is fully subject to the provisions of the EMC Directive and must be CE marked if it is intended to be placed on the market for distribution or final use. If this is not the case, CE marking is not mandatory. However, the manufacturer has to provide such products with relevant instructions to enable use of the apparatus in which they will be incorporated in accordance with the intended purpose. These instructions must indicate EMC aspects to be recognized by the manufacturer of the final apparatus to help in solving foreseeable EMC problems of the final apparatus.

A system is regarded as a final apparatus that must comply with the EMC Directive if it comprises several finished products, apparatuses, or components that are combined, designed, or put together by the same person (system manufacturer). A final apparatus is marketed as a single functional unit for an end-user, and its various parts are designed for installment and operation together to perform a specific task.

An illustrative example is a computer central processing unit (cpu) composed of a power supply, CD-ROM, motherboard, and disk drive in an enclosure. This system is to be regarded as an apparatus, which has to comply fully with the EMC Directive. If the manufacturer of each part of such a system has already applied the directive in full—each unit has its own CE mark—and the manufacturer has given particular consideration to the expected electromagnetic environment and the intended system, the unit as a whole might comply. Experience has shown, however, that this is not always the case.

A system consisting of an optional combination of CE-marked apparatuses, not intended for placement together on the market as a single functional unit, needs neither an additional CE marking nor an additional EC declaration of conformity for the system as a whole. The EMC Directive has already produced its effect if all apparatus are CE marked, assuming that the EMC environment is not different from the one intended by the manufacturer(s) of the individual apparatus incorporated into the system.

An illustrative example is a system consisting of a cpu, keyboard, printer, and monitor.

The guidelines include an important additional comment. System manufacturers should be aware that combining two or more CE-marked subassemblies may not automatically produce a system that meets the requirements of the relevant standard. For example, CE-marked PLCs and motor drives housed together within a machine tool and placed on the market as a system may fail the requirements. By contrast, a high-fidelity system composed of a separately CE-marked amplifier, tuner, CD player, and cassette deck that are wired up correctly is quite likely to maintain its compliance.

An installation, in the broadest sense, is defined as a combination of several finished products or components that are assembled by an installer at a given place. The various parts of the installation are intended to operate together in a particular environment and to perform a specific task; however, the parts are not intended for placement on the market as a single functional or commercial unit.

Such an installation cannot move freely within the EEA market and, with respect to the EMC Directive, there is no need for CE marking or an EC Declaration of Conformity, or for involving a competent body. The installation must, however, comply with the EMC requirements of the directive. The EMC assembly instructions given by the manufacturer, as well as the whole method of installation, must be in accordance with good engineering practices within the context of installations, as well as installation rules.

Installations designed to move to and operate in a range of locations may experience or cause changes in the electromagnetic environment. Like a system, such a movable installation must also be in compliance with the directive.

A system manufacturer (assembler or integrator) can follow a worst-case approach as a way to simplify the task to show compliance of variants of a complete or complex configuration. Once a worst-case configuration is in conformity, the manufacturer may place on the market any of its possible variants or configurations without further verification, assuming that they do not introduce new EMC problems not covered in the worst-case configuration. The manufacturer may in this case draw up and sign the EC declaration to each variant. If the manufacturer (assembler or integrator) later wants to add some new components that were not included in the original worst-case configuration, further verifications are not necessary if they concern electromagnetically irrelevant components. The manufacturer then just signs the EC declaration of conformity and affixes the CE marking to the configuration(s).

Electromagnetically irrelevant components or subassemblies are defined as liable neither to cause electromagnetic disturbances nor to have their performance degraded by them. As such, the components or subassemblies will not influence EMC characteristics when integrated.

The directive does not apply or reapply to a repaired or reconfigured apparatus that has been modified with restoration as the intent. Only if equipment is considered "as-new apparatus" will the directive apply or reapply to a reconfigured apparatus that has been modified with the addition (upgrading) or the removal (downgrading) of one or more parts. Note, however, that though the modification may not result in an as-new apparatus, the modifier must, in any case, document any changes, EMC analysis, tests carried out, and the modifier's final conclusions. In certain cases, the modified configuration already may have been envisaged and documented by the original manufacturer as an EMC-confirmed variant. In such instances, the EMC Directive does not need to be reapplied.