Electro magnetic compatibility
Electro Magnetic Compatibility (EMC)
EMC is concerned with radio frequency interference between electrical equipment, put simply it is the interference that is sometimes occurs between items such as a TV and a Hi-Fi system.
EMC stands for Electro Magnetic Compatibility, and describes the way electric or electronic apparatus behave (regarding Electro Magnetic aspects) in the presence of other equipment. This discipline investigates the unwantedly emitted radio interferences (emissions), and unwanted susceptibility of electronics against Electro Magnetic fields and a number of associated phenomena , known to interfere with electronics in a similar way.
Phenomena like:
Electro Magnetic fields (radio waves) Electrostatic Discharges Fast impulses on supply and other leads Lightning pulses on supply and other leads Magnetic fields and their impact on electronic components Common Mode Voltages and Currents on all cabling Mains Fluctuation and Harmonic Currents effects
The EMC-Directive (2004/108/EEC)
The introduction of the ce mark has lead to a number of so-called New Approach directives, one of which is the EMC-directive.
The technical goal of this directive is two-way:
- Protect the radio spectrum against interfering equipment
- Protect equipment from common interference
All this within the higher goal of preventing trade barriers between the member states of the European Community as introduced the treaty of Rome (1957).
The EMC directive is part of the Framework of New Approach Directives governed by the CE marking directive.
As all ce related directives this is a New Approach Directive, which means that legal requirements to your equipment regarding EMC are described in global terms, called Essential Requirements, where the technical requirements are created and maintained by the market -currently by mandate of the European Commission- by bodies such as ISO, IEC, CENELEC and ETSI in the form of technical standards.
The assessment of compliance with the directive is being governed by two articles in the EMC-directive:
Manufacturers declaration (route acc. art. 10.1) Type testing using a Technical Construction File (TCF) (route acc. to art. 10.2)
Article 10.1 Manufacturers Declaration
The manufacturers declaration consists of a liability statement from the manufacturer or importing agent in which he accepts the legal consequences (liability) for conformity of its equipment to the EMC directives essential requirements. The manufacturer is granted permission to do the assessment himself, or to outsource it to any test-house. Using this route the manufacturer is however, bounded to apply the so called Harmonized Standards for "type testing". These standards are especially listed for this purpose and published in the official news-letter of the EC (OJEC), and in the official journals of all EC-members.
Type testing is the term reserved within the "New Approach" for verifying and proving the compliance of production numbers of equipment by verifying only one sample, assisted by an optional statistical analysis.