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Electromagnetic Compatibility (EMC) directive


The new EMC directive (2014/30/EU) has been published and will come into force on 20 April 2016.

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.

In the UK, the Directive is enforced by the Trading Standards Service and Ofcom. Penalties for non-compliance can include three months imprisonment and a £5000 fine but generally involves a recall and replacement of the affected product.

:!: See also Automotive Electromagnetic Compatibility Directive


Purpose


The Electromagnetic Compatibility (EMC) Directive 2004/108/EC is one a series of measures introduced under Article 100a of the Treaty of Rome. Article 100a directives all have the primary objective of creating a single European market in goods and services with the objective of providing producers and consumers with the benefits of economies of scale that this offers.

The effect of the Directive has been to introduce identical requirements for the EMC performance of electrical apparatus in every country within the European Economic Area (EEA). These requirements are intended to ensure that electrical apparatus will function without causing or being affected by undue interference to or from other apparatus. As the number and type of electronic devices in homes and businesses across Europe increases, the Directive is an important measure to ensure that equipment will continue to function as its makers intend and purchasers have a right to expect.

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.

History


The original EMC Directive, 89/336/EEC, was enacted in 1989 and came into force on 1 January 1992 with a transitional period ending on 31 December 1995. The Directive has been amended several times - Directive 92/31/EC extended the transitional period to allow manufacturers more time to implement the requirements and in 1993 Directive 93/68/EEC aligned the CE marking requirements more closely with those of the other New Approach Directives. Directive 98/13/EC amended the requirements for certain telecommunciations apparatus, and was itself later replaced by Directive 99/5/EC.

Following a long period of development and consultation, a new EMC Directive, 2004/108/EC, was finally published in the Official Journal of the EU on 31 December 2004. The new Directive came into force on 20 July 2007 with a transitional period ending on 20 July 2009. The fundamental protection requirements of the new directive remain the same as those of the old one, but there were certain changes in the administrative and attestation requirements.

Other directives have also affected the scope of the EMC Directive without actually changing its wording and hence are not mentioned in the consolidated text. Directive 93/42/EC on Medical Devices, 95/54/EC on EMC for automotive applications and 2004/22/EC on measuring instruments are all examples, the effect in each case being to exclude equipment covered by the more specific 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.

Enforcement


The Directive is implemented in the UK by the Electromagnetic Compatibility Regulations 2006.

The Directive is enforced in the United Kingdom by the Trading Standards Service and Ofcom. For practical purposes, other bodies (e.g. the Health and Safety Executive) may also be involved in investigations into non-compliant products.

Penalties


The maximum penalty for the supply of non-compliant equipment is three months imprisonment and/or a £5000 fine. More normally the manufacturer would be required to recall or replace any non-compliant apparatus. The enforcing authorities have the power to suspend or prohibit sale of apparatus for which they have reasonable evidence that it does not comply.

EMC assessment


In order to show that a product complies with the essential requirements, its manufacturer is required to complete an ‘EMC assessment’ which provides a record of a technical analysis justifying a manufacturer’s claim of compliance.

Tests


Tests are an alternative to an assessment. Tests are not mandatory under the Directive but it can often be difficult to be sure of a product’s EMC performance without them. Even where testing is useful, the tests can be performed by a manufacturer in house, they do not have to be performed by a Notified Body.

For the purposes of being able to test whether or not equipment complies with the Directive, tests are divided into five classes:

  1. Radiated emissions - Checks to ensure that the product does not emit unwanted radio signals;
  2. Conducted emissions - Checks to ensure the product does not send out unwanted signals along its supply connections and connections to any other apparatus;
  3. Radiated susceptibility - Checks that the product can withstand a typical level of radiated electromagnetic pollution;
  4. Conducted susceptibility - Checks that the product can withstand a typical level of noise on the power and other connections.
  5. Electrostatic discharge - Checks that the product is immune to a reasonable amount of static electricity.

Definitions of the levels above which emissions are defined as unwanted or below which pollution and noise are accepted as being reasonable are contained in the relevant test standards. The manufacturer (and any test house performing tests on the equipment) must agree on which of the various standards for each category apply to the product in question. Since the different standards have different levels for emissions or immunity, it would theoretically be possible for the same product to be acceptable in one application but not in another - for instance noise emission levels acceptable in an industrial environment may be excessive when created in a domestic setting. In practice the scope of the different standards is fairly clearly defined, but even so it is important for manufacturers or importers of products to have a good idea of where they are intending their product to be used.

Administrative requirements


While the essence of the Directive is, of course, to ensure that products meet the essential protection requirements for immunity and emissions, the Directive also has certain administrative requirements. These are as follows:

Compile technical documentation - the manufacturer must produce a file of evidence which describes the product and how it is shown to comply with the Directive. This will typically include information on how to identify the equipment, a copy of the instructions, the EMC assessment, and any test data.

Control of production - although tests may be performed on a sample of the equipment, the Directive requires that all units produced comply with its requirements. The manufacturer will need appropriate quality control procedures accordingly.

Sign a Declaration of Conformity - the manufacturer must sign a document to identify the equipment and confirm the steps they have taken to comply with the Directive. This document is kept on file by the manufacturer ­ it does not need to be sent to any official body (although sometimes customers may ask to see it).

Put the CE logo on the product - it must be put on the equipment, or on its packaging or instructions.

Self-built equipment


Equipment manufactured for the manufacturer's own use is not excluded from the Directive, but does not need to carry the CE logo or meet any of the other administrative requirements of the Directive.

Realities


Most manufacturers of electrical products have little to fear from the EMC Directive and compliance will be straightforward so long as they take a logical approach to the requirements and maintain accurate records. Manufacturers of more complex electronic products may have to spend some time and money testing equipment they are not already completely confident of the EMC performance.

Many consultants and test houses are offering services to help manufacturers to meet their EMC obligations so companies which do have problems have no shortage of people to whom to turn for help. However, it is important to be sure that you actually have a problem before spending time and money trying to solve it. Remember that consultants and test houses have a vested interest in getting you to spend money on their services, so a little time spent doing some basic familiarisation research for yourself may well be a good investment.

The bulk of the EMC standards are to do with setting up and performing tests in such a way as to be able to get reasonably meaningful and repeatable results. What the test labs do not tend to admit is that this doesn't always work. There is a 6dB margin of error permitted in the measurements under most standards and the same product tested to the same standard in different labs quite often gives results which vary by 10dB or more.

It is vital to understand that the EMC Directive does not actually require you to perform testing, it simply requires you to comply with the protection requirements outlined above. For simple electrical apparatus containing only electromechanical controls and induction motors, one can have a reasonable level of certainty that equipment will comply with these requirements (i.e. will meet the levels defined in the standards) without ever actually needing to do any testing. Even where testing is required, it may be that only partial testing is needed to determine performance in one particular aspect (e.g. performance under flickering mains conditions).

There are a number of strategies available to deal with the Directive. One is to bite the bullet and test every piece of apparatus comprehensively. This is expensive and it doesn't really guarantee compliance since it is possible that the standards are not appropriate for the actual application that the equipment is being sold for.

Another strategy is to ignore the EMC issue completely, or at least to assume that the products will comply and that testing will only be an expensive way to prove this. The dangers in this approach are obvious and it cannot be recommended to any reputable manufacturer.

The best strategy is to learn enough about EMC and the requirements of the Directive that you can spend a reasonable testing budget in a way that actually gives you both useful design information and some confidence that your products comply.

Useful links


The European Commission have a special section on EMC with a great deal of useful information on their EUROPA server. This includes the full text of the directive, lists of the current harmonised standards as well as guidance documents and a list of notified bodies.

The UK government's Department of Business, Innovation and Skills also have a section of their site with useful information and guides.

Cherry Clough Consultants website is another useful resource of information about EMC related design and compliance.

Further advice


As with all CE marking directives, the actual requirements for any piece of equipment under the Directive and harmonised standards can be complex and dependent on not only the design but also the type of user, the intended use and sometimes even what is claimed in the instructions or sales literature.

Conformance are not an EMC test laboratory, nor do we specialise in EMC related design. We do, however, know several people who are specialists and we're happy to recommend reputable test laboratories to clients where testing is actually necessary. We also have extensive experience of applying the requirements of the Directive and CE marking equipment as part of a package where (as is usually the case) the EMC Directive is only one of several directives which have to be considered.

For further advice specific to your products, please contact us at Conformance and we will be pleased to discuss your needs.

emc.txt · Last modified: 2014/07/15 15:16 by Karen
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