Electromagnetic Compatibility (EMC) Testing.
The EMC Directive?
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- The EMC Directive 89/336/EEC, amended by 91/263/EEC, 92/31/EEC and 93/68/EEC
- Great Britain: The EMC Regulations 1992 (Statutory Instrument 2372)
- Compliance with directive has been mandatory since 1996
- The EMC Directive is a New Approach Directive. This means it has been drafted in a
general way and does not enter into technical details
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What is EMC Testing?
Electromagnetic Compatibility or EMC is defined as the ability of a product to operate
within its intended electromagnetic environment and to accept or emit RF disturbances
within defined limits with the electromagnetic spectrum.
Broadly EMC testing can be categorised into two areas:
· Emissions - The electromagnetic disturbance that an apparatus generates, must
not exceed a level thus allowing radio equipment, telecommunications equipment and other
relevant apparatus to operate as intended.
· Immunity - The apparatus should have an adequate level of intrinsic immunity to
electromagnetic disturbance so that it can operate as intended when it is properly
installed, maintained and used.
Although all apparatus coming under the scope of this Directive must comply with its
provisions, the maximum EM disturbance generated shall be such as not to hinder the use,
in particular of the following:
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- Domestic appliances and household electronic equipment
- Mobile radio and commercial radio telephone equipment
- Domestic radio and TV receivers
- Industrial manufacturing equipment
- Medical and scientific apparatus
- Information technology equipment
- Aeronautical and marine radio apparatus
- Educational electronic equipment
- Telecommunications networks and apparatus
- Radio and TV broadcast transmitters
- Lights and fluorescent lamps
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When is EMC Testing Needed?
· The EMC Directive applies to:
"Any apparatus liable to cause EM disturbance or the performance of which is
liable to be affected by such a disturbance"
· An apparatus is defined as:
"An electrical or electronic appliance or system consisting of a finished product
or products, having an intrinsic function which is intended for the end user and is a
single commercial unit"
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- Exceptions to EMC testing include:
- Apparatus for export outside of European Economic Area
- Excluded installations
- Spare parts
- Second hand - pre-dates the directive
- Apparatus used in a sealed EM environment
- Military equipment
- Apparatus wholly covered by other directives
- Radio amateur apparatus (not commercially available)
- Motor vehicles (covered by separate directive)
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What Are The Three Routes to Conformity?
The Standards Route:
This is for apparatus other than radio communication transmitting apparatus. It involves
Self-Certification by the manufacturer using the appropriate harmonised European
standards, EN standards.
The Technical Construction Route:
This can be used for products other than radio transmitting apparatus. A common technical
construction file can be used to cover a range of products, key testing may be required,
and the TCF is assessed by a competent body who issue a report/certificate.
The EC Type Examination Route:
For radio communication transmitting apparatus including mobile phones, an EC type
examination certificate is issued by a 'Notified Body' appointed by the DTI
Why Do I Need to test?
Manufacturers and importers putting electrical products into the EU market are required to
show due diligence to the requirements of the EMC Directive. They affix a CE mark and sign
a declaration of conformity which is a legally-binding self-declaration that the essential
requirements of the directive have been met by the product type. If this declaration is
questioned by the authorities, the manufacturer/importer has to be able to show what EMC
rationale his declaration is based on. The more evidence available, the stronger the case.
The decision whether to test the product or not is therefore a risk assessment, the risk
of prosecution versus testing cost. The spectrum of possibilities in order of decreasing
risk are: no testing, testing in-house by the manufacturer / importer, testing at a
non-accredited EMC test house and testing at an accredited EMC test house. The latter
option therefore represents minimum risk.
What are the Penalties for Failing to Comply?
The maximum penalty for putting non-compliant products into the single market is 3 months
imprisonment and/or £5000 fine. A product recall or replacement exercise could also be
enforced as could a prohibition or suspension of product sales.
Who enforces the EMC Directive?
In the UK the EMC Directive is enforced by the Trading Standards Service.
Where must the CE mark be affixed?
The CE mark must be affixed on either the product, its instructions or packaging.
Does CE + CE=CE?
Combining CE marked sub-assemblies and components into a final product does not guarantee
EMC compliance of the finished product.
The Cost of Compliance.
Which Standards Are Applicable?
Euro Norm (EN) Specific Standards:
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- EN 55014 Household electrical appliances, portable tools and similar electrical
apparatus Emissions
- EN 55015 Fluorescent lamps and luminaries emissions
- EN 55022 Information technology equipment emissions
- EN 60555 Household appliances and similar electrical equipment mains harmonics
- EN 60601-1 Medical equipment emissions and immunity
- EN 60945 Maritime equipment emissions and immunity
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EN Generic Standards:
These are used when no specific standards can be applied.
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- EN 61000-6-3 Emission standard for residential, commercial and light-industrial
environments
- EN 61000-6-1 Immunity for residential, commercial and light-industrial environments
- EN 61000-6-4 Emission standard for industrial environments
- EN 61000-6-2 Immunity for industrial environments
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Other Standards:
Note, these are not applicable to CE, but are international standards.
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China
- CNS 13438
Canada
- CSA 108.8
Japan
- VCCI Class 1/2
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USA
- FCC CFR47 Part 15
- ANSI C63.4
Australia
AS/NZS 3548
AS/NZS 4251.1
AS/NZS 4252.1
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Typical Testing Areas and Reasons for Failure? 
EN 50081 Emissions:
Conducted Emissions
- Inflicting noise on incoming mains
- Filtering may be required
- Cable routing important
Radiated Emissions
- Emitting noise into environment via interconnecting leads, poorly earthed enclosure,
unscreened cable, etc.
EN 50082 Immunity:
Conducted Immunity
- Effect on equipment from incoming noise on mains
- Fast burst transients
- Surge
- Voltage interruptions
Radiated Immunity
- Effect on equipment from external electromagnetic & electrostatic fields. E&H
Created By Brett Walton
For more information about how Wemtech can help, please contact Mike Foster on 01527
595066.
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