The global recession has not prevented EMC standardization work from marching relentlessly forward. Work within CISPR is no exception and this year delegates and experts will meet in Lyon, France in September under the auspices of the current chairman Don Heirman (US) and secretary Steve Colclough (UK). For those of you new to EMC, CISPR is an international special committee on radio interference within the International Electrotechnical Commission (IEC). As defined on the IEC website for CISPR, CISPR’s principal task is at the higher end of the frequency range, from 9 kHz upwards, preparing standards that offer protection of radio reception from interference sources such as electrical appliances of all types, the electricity supply system, industrial, scientific and electromedical RF, broadcasting receivers (sound and TV) and, increasingly, IT equipment (ITE). Following is a brief overview of the scope of CISPR’s current activities in 2009, close to 75 years after its founding in 1935.
CISPR Sub-committee (SC) A provides basic standards to CISPR product committees as well as other IEC technical committees for use in determining conformity to limits. Activity specifically involves radio-interference measurements and statistical methods.
CISPR SCA Active Projects – Measuring Apparatus
CISPR 16-1-1 has been rewritten concerning the use of spectrum analyzers without pre-selection for compliance measurements.
A new CISPR 16-1-6 project on antenna calibration was started in the past year and will update the current CISPR 16-1-5, add time domain techniques, and will apply additionally to frequencies above 1 GHz.
CISPR 16-1-4 and 16-1-5 will be amended for the introduction of the Reference Site Method which offers an improvement on the method of validation of reference test sites through the use of the AAPR Antenna Pair Reference. This AAPR includes the antenna factors as well as the coupling of each antenna to the ground plane and the coupling between the antennas. In addition, the radiation patterns of the antennas are included as compared to the NSA method where the radiation patterns are approximated Hertzian dipoles. Round-robin tests have already provided valuable input and a much improved second draft is circulating.
Although already included for frequencies below 1 GHz, the evaluation of the set up table on the impact of the EUT emissions can now be measured and included in the uncertainty budget also now above 1 GHz in CISPR 16-1-4 Ed 3.0. Such tables have historically been made of wood but the above 1 GHz test will require the use of different lower reflection dielectric materials. Experience is still limited but the market is already starting to see the emergence of specialised tables to suit this requirement. The second edition of CISPR 17 on “Measurement of EMC Characteristics of RF Filters” is at second stage Committee Draft (CD).
CISPR SCA Active Projects – Test Methods
- CISPR 16-2-1 Conducted disturbance measurements concerning effect of cable bundling
- CISPR 16-2-3 Addition of measurand for radiated emissions less than 1 GHz
- CISPR 16-2-3 Addition of receiving antenna height scan above 1 GHz
- CISPR 16-2-3 Application of Common Mode Absorbing Device (CMAD).
CISPR SCA Active Projects – Uncertainty
- CISPR 16-4-1 Treatment of uncertainties in compliance criteria
- CISPR 16-4-2 Amendment on measurement instrumentation uncertainty
CISPR SC B Industrial, Scientific and Medical (ISM) Standards
- CISPR 11 – The future Ed 5.0 is currently under revision with key issues related to harmonizing methods with CISPR 16
CISPR SC D Vehicle, Boats and Internal Combustion Engines Standards
- CISPR 12 (off board receiver emissions) and CISPR 25 (on-board receiver emissions) – Maintenance continues
CISPR SC F Household Appliances, Electric Tools and Similar Apparatus Standards
- CISPR 14 Consumer (Immunity and Emission ) – No major work underway; currently active
- CISPR 15 Lighting – SC F is working with SC A on use of Coupling-Decoupling Networks (CDN)
CISPR SC I Information Technology, Multimedia, and Receiver Products
- CISPR 13 Broadcast receivers and associated equipment recently published; Ed 6.0 included emission limits to 6 GHz
- CISPR 22 ITE recently published Ed 6.0; included emission limit changes to 6 GHz
- CISPR 32 Multimedia is currently one of the major activities within CISPR. A first draft of this standard received over 1000 comments; a second draft is now circulating taking into account those comments as appropriate. Of interest is the continued debate on a general level concerning referee or alternative methods which were originally highlighted by the first draft inclusion of chamber, TEM cell and mode stirred methods all in the normative section. The latter two have now been placed into an informative annex as the IEC-CISPR national committees have positioned itself with referee methods at this time stating that: “If more than one adequate test method exists for a characteristic, only one shall in principle be the subject of a document. If, for any reason, more than one test method is to be standardized, either the referee (often called “reference”) method shall be identified in the document or the intended (equal) validity shall be stated.”
- Requirements and Measurement Methods for Power Line Telecommunications (PLT) Equipment –The issue is to allow the same level of radio protection while placing IT signals on the mains cord that are at the higher levels allowed for mains in the frequency range 150 kHz to 30 MHz. Presently the rationale for this work is being prepared. One approach is to have notches in the PLT spectrum where at those critical frequencies; there is significant reduction in the applied signal. Such notches are suggested for the amateur radio band as an example.
A semi-anechoic 10 meter chamber for automotive EMC compliance testing in accordance with CISPR 12, which describes the radio disturbance characteristics – limits and methods of measurement – for vehicles, boats and internal combustion engine driven devices. Many CISPR 12 chambers may also be used for testing in accordance with other automotive standards, such as SAE J551 and ISO 11451-2, as well as CISPR 25. (Photo used with permission of ETS-Lindgren)
CISPR JTF Work
CISPR has setup a number of internal Joint Task Forces (JTFs) or cross sub-committee groups to facilitate an improved application of test methods (using the output of
SC A) and better use of the interference model
(provided by SC H).
- A/D Development of a chamber validation method for CISPR 25. This will be separated in two parts: (1) below 30 MHz and (2) 30-1000 MHz
- A/D Inclusion of Fast Fourier Transform (FFT) based instrumentation in CISPR 16 to use new time domain based technology
- A/F CDN measurement – the task is to transfer the methods for measuring conducted emissions from luminaries from CISPR 15 into CISPR 16
- A/I Common measurement methods so that the SC I standards using SC A basic measurement techniques simply reference them in the product standard; also to suggest that techniques used in SC I and not in CISPR 16 be added to CISPR 16 so that they can be removed from SC I publications and simply refer to the CISPR 16 documents
- A/H Limits, especially those for new measurement techniques for use by the product committees
IEC SC 77B / CISPR JTF Work
IEC/CISPR has also set up a number of joint task forces with IEC SC 77B, which is under the Technical Committee (TC) 77 umbrella. The main task of TC 77 and its three sub-committees (including SC 77B) is to prepare basic and generic EMC publications specifying electromagnetic environments, emissions, immunity, test procedures, measurement techniques, etc. SC 77B specifically handles high-frequency continuous and transient phenomena, including electrostatic discharges, for example. It has the responsibility for the publication of the following:
- IEC 61000-4-20: The TEM Cell JTF has completed its first maintenance cycle and been revised to include field probe calibration, provision for large EUTs and harmonized test setups for immunity and emission. Currently FDIS.
- IEC 61000-4-21 Ed 1.0: The Reverberation Chambers JTF has also completed its first maintenance cycle and is revising to include amongst others: field probe calibration, immunity and emission methods, and measurement uncertainty. Currently at the Final Draft International Standard (FDIS) stage.
- IEC 61000-4-22: Fully Absorber-lined Rooms (FARs). After some delay, the second CD of this draft standard has been sent for Committee Draft for Vote (CDV). The methods described in this document offer an independent and more efficient method of validating a FAR and EUT set up for both radiated immunity and emissions which could exist in parallel to CISPR 16-1-4 and IEC 61000-4-3. It has therefore met with some opposition and the result of the vote is eagerly anticipated within IEC/CISPR. On a related topic, we are seeing more chamber users considering retrofits of existing chambers to replace outdated RF absorber with the newer material available. On many of these 15+ year chambers, the shielded enclosure still performs well; however, the absorber may not have fared so well over the years and performance has been compromised. An article on one user’s experience with a major absorber retrofit appears here.
Whilst some of the Sub-committees have been able to reduce their workload in recent times (in particular SC A) there has been an increase in the scope of the Joint Task Force activities which virtually all include SC A. This is considered a good method to further involve the basic measurement experts with those in product committees that use their outputs. This is born from CISPR’s desire to constantly improve and update all standards whilst harmonizing and optimizing the work involved.
FOR MORE INFORMATION
Please consult the IEC website www.iec.ch or contact your national committee. For more detailed information on the background of CISPR and its current activities, visit this link. This article by Werner Schaefer, email@example.com, was published in the Winter 2009, Issue 220 of the IEEE EMC Society Newsletter.
The author wishes to acknowledge and thank Don Heirman, Chairman of CISPR, for his invaluable review of and contributions to this article. Mr. Heirman can be contacted at firstname.lastname@example.org.
Martin Wiles is a Senior RF Engineer with ETS-Lindgren, in Stevenage, England. He is a UK delegate for CISPR A and the IEC-CISPR Joint Task Force on Fully Anechoic Rooms.
He can be reached by e-mail at email@example.com.