International EMC Standards: Changes Released in 2004

Daniel Hoolihan

Manufacturers of electronic equipment need to keep current with evolving standards to ensure compliance.

Every year, the standards development organizations of the world introduce, revise, and consolidate regulatory standards. Engineering standards are no exception to this pattern of flux, particularly in the area of electromagnetic compatibility (EMC). The calendar year 2004 saw many important EMC standards revised, amended, or released in a new form. This article looks at the year’s more-important changes in the international regulatory environment for EMC and discusses each in a brief overview.

CISPR Standards

Following are the 2004 developments involving standards for electromagnetic emissions and immunity with respect to radio communications that are maintained by the International Special Committee on Radio Interference (CISPR) of the International Electrotechnical Commission (IEC).

CISPR 11, Consolidated, Edition 4.1. Industrial, Scientific, and Medical (ISM) Radio-Frequency Equipment— Electromagnetic Disturbance Characteristics—Limits and Methods of Measurement. This version of CISPR 11, released in June, consolidates the fourth edition of 2003 with its Amendment 1 issued in 2004. Amendment 1 added to the statement of scope that “requirements for ISM lighting apparatus and ultraviolet (UV) irradiators operating at frequencies within the ISM frequency bands defined by the International Telecommunications Union (ITU) Radio Regulations are contained in this standard.” It also added the words “for microwave-powered UV irradiators, the limits specified in Table 6 apply” and inserted a new Table 6 in the standard that addresses both Class A and Class B ISM equipment.

CISPR 16-1-2, Consolidated, Edition 1.1. Specification for Radio Disturbance and Immunity Measuring Apparatus and Methods—Part 1-2: Radio Disturbance and Immunity Measuring Apparatus—Ancillary Equipment—Conducted Disturbances. This is a consolidation of the first edition (2003) of CISPR 16-1-2 with its April 2004 Amendment 1. A new subclause, 5.2.1(high-impedance voltage probe), was added by Amendment 1, and the words from the existing text of subclause 5.2 were moved to that location. The new subclause 5.2.2 (capacitive voltage probe) also was added. It includes a Figure 11 on a “circuit used to make voltage measurement between a cable and a reference ground.” In addition, the amendment introduced the informative annex G on “Construction and Evaluation of Capacitive Voltage Probe (Subclause 5.2.2).” Annex G contains seven figures to aid in the construction and evaluation of the subject probes. Consolidated Edition 1.1 of CISPR 16-1-2 was released in June.

CISPR 16-1-3, Edition 2.0. Specification for Radio Disturbance and Immunity Measuring Apparatus and Methods—Part 1-3: Radio Disturbance and Immunity Measuring

Apparatus—Ancillary Equipment—Disturbance Power. This second edition, released in June, cancels and replaces the first edition published in 2003. It constitutes a technical revision. It specifies a more-detailed calibration method for the absorbing clamp, which is used to measure the radio disturbance power in the frequency range of 30 MHz to 1 GHz, than the first edition did. Furthermore, the second edition introduces new alternative calibration methods that are more practicable than the one specified previously. The document defines additional parameters to describe the absorbing clamp, such as the decoupling factor for the broadband absorber and the decoupling factor for the current transformer, along with their validation methods. A procedure for validating the absorbing clamp test site also appears in the revised standard.

CISPR 16-1-4, Consolidated, Edition 1.1. Specification for Radio Disturbance and Immunity Measuring Apparatus and Methods—Part 1-4: Radio Disturbance and Immunity Measuring Apparatus—Ancillary Equipment—Radiated Disturbances. This May release consolidates the 2003 first edition of the standard CISPR 16-4-1 and its 2004 Amendment 1. The amendment added new definitions for fully anechoic room, quasi-free-space test site, and test volume. It changed subclause 5.7 to read “Test Site Suitability with Ground Plane” and also added a new subclause 5.8, “Test Site Suitability without Ground Plane.” The site performance may be validated by two methods described in the amendment: the site reference method and the normalized site attenuation (NSA) method. Subclause 5.8 includes a graph of “theoretical free-space NSA as a function of the frequency for different measurement distances.” It also includes two figures showing measurement positions for the site validation procedure.

CISPR 16-2-2, Consolidated, Edition 1.1. Specification for Radio Disturbance and Immunity Measuring Apparatus and Methods—Part 2-2: Methods of Measurement of Disturbances and Immunity—Measurement of Disturbance Power. This consolidated version of CISPR 16-2-2 is based on the 2003 first edition and its Amendment 1 of May 2004. It was released in June. Amendment 1 added six new definitions, for lead under test, absorbing clamp measurement method, absorbing clamp test site, clamp factor, clamp reference point, and slide reference point. It replaced the existing clause 7 on measurements using the absorbing clamp with a new version. It also modified Annex A, titled “Historical Background to the Method of Measurement of the Interference Power Produced by Electrical Household and Similar Appliances in the VHF Range.”

CISPR 16-4-3, Edition 2.0. Specification for Radio Disturbance and Immunity Measuring Apparatus and Methods—Part 4-3: Uncertainties, Statistics, and Limit Modeling— Statistical Considerations in the Determination of EMC Compliance of Mass-Produced Products. Issued in May, this second edition of CISPR 16-4-3 cancels and replaces the first edition published in 2003 and constitutes a technical revision. Dealing with statistics used to determine EMC compliance, it includes a new mathematical approach for applying the 80%/80% rule—that is, an 80% degree of confidence that 80% of the appliances of a type being investigated comply with the emission or immunity requirements—based on a method involving an additional acceptance limit. The mathematical basis for this new method is provided. An additional test approach, based on the noncentral t distribution and using frequency subranges, has been added as well, along with a description of the properties of all methods that are available at this time.

CISPR 22, Amendment 1, Edition 4.0. Information Technology Equipment—Radio Disturbance Characteristics—Limits and Methods of Measurement. Amendment 1, issued in October, added a new reference (CISPR 16-1-2:2003) and two new definitions—for total common-mode impedance and for associated equipment—to the 2003 fourth edition. In Annex C, covering possible test setups for common-mode measurements, it changed some paragraphs and added new paragraphs. It also added Figure C.6, a flowchart for selecting the test method. Finally, it added a new Informative Annex F titled “Rationale for Disturbance Measurements and Methods on Telecommunication Ports.”

CISPR 25, Corrected, Edition 2.0. Radio Disturbance Characteristics for the Protection of Receivers Used Onboard Vehicles, Boats, and on Devices—Limits and Methods of Measurement. This standard, whose second edition was published in 2002, is designed to protect receivers from disturbances produced by conducted and radiated emissions arising in a vehicle. The March corrigendum changed “50-ohm/50- microhenry” to “50-ohm/5-microhenry” in paragraph 6.1.2, “Power Supply and Artificial Network.”

CISPR/TR 29, Edition 1.0. Television Broadcast Receivers and Associated Equipment—Immunity haracteristics—Methods of Objective Picture Assessment. CISPR 29 is a technical report that was prepared by CISPR Subcommittee I, which focuses on the EMC of information technology equipment, multimedia equipment, and receivers. This brand-new standard was released in August. It describes the algorithms used for objective picture assessment in immunity tests of analog and digital TV broadcast receivers and associated equipment.

IEC 61000

Following are the changes in the basic IEC standard for EMC.

IEC 61000-3-2, Amended, Edition 2.0. Electromagnetic Compatibility (EMC)—Part 3-2: Limits—Limits of Harmonic Current Emissions (Equipment Input Current  16 A per Phase). This short Amendment 2, released in October, added to the 2000 second edition one standard (ITU-R BT.471-1, “Nomenclature and Description of Color Bar Signals”) to the normative references in clause 2. It also modified Annex C, “Type Test Conditions,” by replacing some text in paragraph C.1 covering test conditions for TV receivers.

IEC 61000-4-4, Edition 2.0. Electromagnetic Compatibility (EMC)—Part 4-4: Testing and Measurement Techniques—Electrical Fast Transient/Burst Immunity Test. This, issued in July, is a basic EMC publication. The second edition cancels and replaces the first edition published in 1995 and its amendments 1 (2000) and 2 (2001), and constitutes a technical revision. The second edition improves and clarifies simulator specifications, test criteria, and test setups. It requires only common-mode injection.

IEC 61000-4-6, Amended, Edition 2.0 Electromagnetic Compatibility (EMC)—Part 4-6: Testing and Measurement Techniques—Immunity to Conducted Disturbances,

Induced by Radio-Frequency Fields. Released in October, this four-page Amendment 1 added Annex F, an informative annex, titled “Test Setup for Large Equipment Under Test (EUTs),” to the 2003 second edition of IEC 61000-4-6. The annex was needed because the test setup in the main body of the standard was not sufficient to cover the needs of some large EUTs that have cables entering or exiting the equipment at heights greater than 1 m. As the upper frequency of the test signal is 80 MHz, EUT size may be considerable with respect to the wavelength and resonance effects that may be present with cables connected to such EUTs.

IEC 61000-4-7, Corrected, Edition 2.0. Electromagnetic Compatibility (EMC)—Part 4-7: Testing and Measurement Techniques—General Guide on Harmonics and Interharmonics Measurements and Instrumentation, for Power Supply Systems and Equipment Connected Thereto. This July corrigendum affects equation system 3 in paragraph 3.1 (“Definitions Related to Frequency Analysis”). The equations for bm and am are corrected by the addition of a fm.

IEC 61000-4-11, Edition 2.0. Electromagnetic Compatibility (EMC)—Part 4-11: Testing and Measurement Techniques—Voltage Dips, Short Interruptions, and Voltage Variations Immunity Tests. This second edition, which was released in March, cancels and replaces the first edition published in 1994 and its Amendment 1 (2000). It constitutes a technical revision in which preferred test values and durations have been added for the various environment classes and in which the tests for three-phase systems have been specified.

This standard applies to electrical and electronic equipment having a rated input current not exceeding 16 A per phase, for connection to 50- or 60-Hz ac networks.

Product Family Standards

The EMC requirements in several product family standards changed in 2004.

IEC 60255-26, Edition 1.0. Electrical Relays—Part 26: Electromagnetic Compatibility Requirements for Measuring Relays and Protective Equipment. This part of IEC 60255 specifies all of the requirements for EMC in a single document. Thus, it is considered an overview document for measuring relays and protection equipment for power system protection, including the control, monitoring, and process interface equipment used with those systems. The detailed test procedures are given in other referenced standards. This standard took effect in August.

IEC 60601-1-2, Amended, Edition 2.0. Medical Electrical Equipment—Part 1-2: General Requirements for Safety—Collateral Standard: Electromagnetic Compatibility— Requirements and Tests. This September amendment
contains the first revisions to the second edition of IEC 60601-1-2, which was published in 2001. It deals primarily with requirements for equipment and systems that comply with CISPR 11 Group 2 Class B except for the third harmonic of the fundamental frequency, are for use by healthcare professionals and not intended for sale to the general public, and are intended to be used in domestic establishments or connected to the public mains network.

The amendment changes the definition of function and adds two new definitions, for professional equipment or system and Type A professional equipment or system. It changes some wording in other paragraphs and replaces Table 201 (“Guidance and Manufacturer’s Declaration—electromagnetic emissions—for all equipment and systems”) with a revised table. In addition, it revises Figures 201 and 202. Amendment 1 added two new informative annexes, as well. These are GGG, “Guidance in the Identification of Essential Performance,” and HHH, “Guidance for Determining If Non-Medical Electrical Equipment Used in a System Is Exempt from the EMC Testing Requirements of This Standard.”

IEC 61800-3, Edition 2.0. Adjustable-Speed Electrical Power Drive Systems—Part 3: EMC Requirements and Specific Test Methods. This second edition, released in August, cancels and replaces the first edition issued in 1996 and constitutes a technical revision. It introduces three key changes:

• The classes of distribution (unrestricted and restricted) of the power drive systems (PDSs) have been replaced by categories of PDS (C1 to C4) having definitions related to the product itself and its intended use.
• Coverage of emission limits is improved.
• An EMC plan is generalized for category C4.

PDSs covered by this standard are those installed in residential, commercial, and industrial locations, with the exception of traction applications, and in electric vehicles. The object of this standard is to define the limits and test methods for a PDS according to its intended use. The standard includes both emission and immunity requirements.

Conclusion

International standards relating to engineering for EMC are always changing in response to usage reports and worldwide R&D activity. The latest versions, amendments, and corrigenda are available through the IEC Web site at www.iec.ch.

Daniel D. Hoolihan is president of EMC Consulting (Lindstrom, MN). He can be reached at hoolihan@emcxpert.com.