Major EMC committees join forces to measure uncertainty
The aim of EMC is to ensure the reliability
and safety of all types of systems wherever
they are used and exposed to
electromagnetic environments
Both of the principal IEC TCs (Technical Committees) that deal with EMC (electromagnetic compatibility) – CISPR, the International Special Committee on Radio Interference, and TC 77: Electromagnetic compatibility – held meetings in Lyon, France, from 21 September to 2 October 2009.
CISPR deals with the protection of radio reception against the unwanted effects of interference caused or emitted by all types of electrical appliances. On one hand, it sets the limits of interference that enable different devices to function in the same electromagnetic environment. On the other, it deals with the instrumentation and the various methods used for measuring those emission levels. Sources of interference include ignition and electricity supply systems, electric transport systems and industrial, scientific and electromedical radiofrequencies, sound and television broadcasting receivers, IT (Information Technology) equipment and so on.
TC 77 prepares International Standards and TRs (Technical Reports) that deal with the correct operation of devices or equipment subjected to electromagnetic disturbance, including network overloading. TC 77 has a horizontal function since it exists to serve the work of many other TCs.
More than 250 delegates attended the various plenary and WG (Working Group) meetings of CISPR and TC 77, which were hosted by UTE (Union Technique de l'Electricité, the French National Committee of the IEC) in the excellent facilities of Lyon’s Centre des Congrès.
Ongoing work of CISPR
- Several SCs (Subcommittees) in CISPR are currently working on introducing the new RMS-Average (root mean square) detector which was developed to provide better protection for digital broadcast services.
- Work is continuing in CISPR/A to develop the use of FFT (fast Fourier transform) measurements. Potentially, this could dramatically reduce the test time for emission measurements.
- CISPR/A is also working on reference site measurements and antenna calibration. Both are important reference documents for test equipment used in emission measurements.
- CISPR/B has set up two maintenance teams. One is studying the important area of micro-generation technologies, or Grid Connected Power Conditioners. The other is developing a new method of measuring emissions from microwave ovens based on Amplitude Probability Density.
- CISPR/D is working on developing suitable standards to cover new vehicular technologies such as hybrid and all-electric drive systems.
- CISPR/F has introduced radiated emissions testing for battery-driven products that previously might not have been the object of testing.
- CISPR/I is continuing with work on new International Standards for multimedia products.
- On a general level all the CISPR SCs work together with IEC TCs and external organizations to develop standards that continue to provide adequate protection for all users of the radio spectrum, while at the same time make use of the latest measurement techniques and cover the ever-converging technologies seen in products in the marketplace.
The steering committee, which consists of both CISPR SC and IEC TC members, held three meetings in Lyon. This highly active group includes not only the CISPR Chairman and Vice-Chairman, the Chairmen of all the CISPR SCs and representatives of each liaison body and NCs (National Committees), but also representatives from all the other Member Bodies of CISPR.
The Member Bodies of CISPR are:
- CIGRE (International Council on Large Electric Systems)
- EBU (European Broadcasting Union)
- ETSI (European Telecommunications Standards Institute)
- IARU (International Amateur Radio Union)
- ITU-R (International Telecommunications Union - Radio-communications Sector)
One of the major management activities of the steering committee is that of tracking projects. The steering committee ensures that all the work carried out by SCs CISPR/A, which provides the methodology for measuring, and CISPR/H, which sets the limits for measurement, is relevant to the work of the other SCs B, D, F and I. If there is no product committee interest, they then review whether or not to continue that activity.
Other more focussed inputs to the SCs come by way of the CAG (Chairman’s Advisory Group), which consists of the Chairs of SCs and the CISPR Chairman, Vice-Chairman, Secretary and Technical Officer. These SC meetings continue throughout the year between plenary meetings using electronic means such as teleconferences.
TC 77, SC 77A: Low frequency phenomena, SC 77B: High frequency phenomena, and SC 77C: High power transient phenomena, have worked hard at maintaining several of the standards in the best selling IEC 61000 series, which was reported about in the August 2009 e-tech.
Recently, TC 77 and CISPR/A set up a new JTF (Joint Task Force) on Measurement Uncertainty. This new JTF is set to develop a TR to provide guidance on uncertainty for immunity testing. The uncertainty of measurement in emissions is covered by CISPR in the publication CISPR-16-4-2, Measurement instrumentation uncertainty.
CISPR, the International Special Committee on Radio Interference
CISPR has a number of functions. First, it exists to protect against radio reception interference that is caused by electrical appliances, ignition systems and electricity supply systems, including electric transport systems; industrial, scientific and electromedical radiofrequencies (but excluding radiation from transmitters intended to convey information); sound and television broadcasting receivers; and IT (Information Technology) equipment. Second, it deals with the equipment and the methods that are used to measure interference. Finally, it defines the limits of the interference that is caused by the various sources listed.
Subcommittees in CISPR
SC A (SC CISPR/A): Radio-interference measurements and statistical methods, covers radio-interference measurements and statistical methods and is responsible for the CISPR 16 series of standards. It specifies EMC instrumentation, EMC measurement techniques, uncertainties, statistical methods and limit modelling. At present, it is working on improving existing standards as well as developing new methods and techniques.
SC B (SC CISPR/B): Interference relating to industrial, scientific and medical radio-frequency apparatus, to other (heavy) industrial equipment, to overhead power lines, to high-voltage equipment and to electric traction, handles interference relating to industrial, scientific and medical RF (Radio Frequency) apparatus.
SC D (SC CISPR/D): Electromagnetic disturbances related to electric/electronic equipment on vehicles and internal combustion engine powered devices, deals with EM (Electromagnetic) disturbances related to electric and electronic equipment on vehicles and devices powered by internal-combustion engines.
SC F (SC CISPR/F): Interference relating to household appliances tools, lighting equipment and similar apparatus, covers interference relating to household appliances, tools, lighting and similar equipment.
SC H, (SC CISPR/H), Limits for the protection of radio services, sets the levels for each different product type or family of devices depending on use and develops generic emission standards.
SC I, (SC CISPR/I): Electromagnetic compatibility of IT equipment, multimedia equipment and receivers, made up of the former SCs E and G, deals with the EMC of ITE (Information Technology Equipment), multimedia equipment and receivers, and is working on new emission and immunity standards. ITE includes audio, video and/or broadcast receiving equipment or a combination of these functions, such as radio and television receivers, audio amplifiers, DVD players, portable entertainment devices, for example, CD players, computers and peripheral equipment, routers, hubs and switches, telecommunication equipment, gaming machines, audio/video equipment intended to be mounted in vehicles, electronic musical instruments.
Liaisons
When a TC works on a project with another TC or an outside entity this is known as a technical liaison.
There are three levels of liaisons that involve the many specialized technical sectors within the IEC and other organizations:
Category A: Organizations take an active part in the work of the TC/SC concerned and attend meetings as observers.
Category B: The parties concerned simply exchange information.
Category D: Organizations participate at WG (Working Group) or project level. This category was first approved by the SMB (Standardization Management Board, then known as the Committee of Action), in December 1996. It concerns organizations which can make an effective technical contribution at the development stages. The category applies to organizations, not individual persons. Potential liaison organizations can include manufacturing associations, commercial organizations, industrial consortia, user groups and professional and scientific entities.
Category D liaison organizations have to meet a number of acceptance criteria:
- They need to be multinational with individual, company or country membership
- be willing to make a contribution to IEC work
- be sufficiently representative within their defined area of competence
Note that there is also a Category C liaison which applies to ISO (International Organization for Standardization) /IEC JTC (Joint technical Committee) 1 work only.
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