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The Taiwanese EMC Standard CNS 13803 Compared with CISPR 11Michael J. Alvarado and Grace LinThe national standard varies from the source standard in ways that could affect the ease of market entry in Taiwan.The Taiwanese regulatory agency responsible for EMC regulation, the Bureau of Standards, Metrology, and Inspection (BSMI), has begun to implement EMC requirements for industrial, scientific, and medical (ISM) radio-frequency equipment. Such devices must meet the requirements of the Chinese national standard CNS 13803:1997 before they can be placed on the market in Taiwan. CNS 13803:1997 is similar to CISPR 11:1990, on which it is based. Both standards are titled "Limits and Methods of Measurement of Electromagnetic Disturbance Characteristics of Industrial, Scientific, and Medical (ISM) Radio-Frequency Equipment." But there are some differences between the standards that, if not understood, could delay receipt of EMC approval for a product intended to be marketed in Taiwan. This article examines the scope of CNS 13803, focusing on its deviations from the CISPR standards. Table I itemizes the points of difference between the International Electrotechnical Commission (IEC) standard and its Taiwanese counterpart.
ISM Frequencies The ISM-designated frequency bands are exempted from emission requirements in both CNS 13803 and CISPR 11. This means that there are no radiation limitations for frequencies falling within the designated ranges. CNS 13803 specifies 6 ISM frequencies, by contrast with the 12 specified by CISPR 11, because the Taiwanese Directorate General of Telecommunications allocated only that many bands. Thus, products designed in accordance with CISPR 11 requirements may not comply with CNS 13803 requirements, depending on their ISM-designated frequencies. (See the part of Table I pertaining to Section 3 of the standards.) Annexes to the Standards CNS 13803 has five annexes, numbered 1 through 5, whereas CISPR 11 refers to its four annexes as A, B, C, and D. The first four CNS 13803 annexes are equivalent to the CISPR 11 annexes. The fifth CNS 13803 annex is based on CISPR 23:1987; four annexes were taken from CISPR 23 to make up Annex 5 of CNS 13803, which provides background on the determination of limits for ISM equipment. Measurement Distance BSMI accepts test data for Group 2 Class A equipment taken at the 10-m measurement distance and adjusted by the interpolation method (L2 = L1[d1/d2]) for the radiation disturbance limits (as specified in CISPR 22:1997, "Information Technology Equipment—Radio Disturbance Characteristics—Limits and Methods of Measurement"). This alternate method is allowable owing to the population density of Taiwan. A 30-m test facility is not practical on the crowded island. CISPR 11 allows measurements made at a closer distance, but "no correction is allowed for in the limits." This closer distance is defined as the distance between the equipment under test and the measuring antenna. Test Report An EMC-compliance test report must include the information specified in Section 13, "Certificates and Reports," of ISO Guide 25, "General Requirements for the Competence of Calibration and Testing Laboratories," 1990. A test laboratory is qualified to issue a CNS 13803 report only after obtaining accreditation from the BSMI. CNS 13803 is within the scope of the mutual recognition agreement between Taiwan and the United States that became effective August 1, 1999. However, no test laboratories in the United States are applying for accreditation for this standard at this time. Currently, only five EMC test laboratories are accredited by the BSMI to perform EMC compliance testing for CNS 13803. They are all located in Taiwan. Information about them can be found at the BSMI Web site (http://www.bsmi.gov.tw). BSMI-accredited test laboratories qualified to perform CNS 13803 testing are assigned an accreditation number with the format SL2-IS-E-XXXX, the numerals in the last four positions denoting the particular laboratory. Type Approval Manufacturers and importers are required to apply for a BSMI type approval for regulated products they wish to market in Taiwan. The type-approval procedure is spelled out at the BSMI Web site. In addition to a test report, five technical documents must be submitted with the application: a user manual, the BSMI label location, a block diagram, EMC modifications and clock frequencies, and a product catalog and photographs. These required documents could be part of the test report. Conclusion ISM frequencies should be the main concern when a product intended for the Taiwanese market is designed. The safe way to design such a product is to use one of the ISM-designated frequency bands specified in CNS 13803 and CISPR 11 in common. The first two categories of regulated industrial and scientific products mandated to comply with the EMC requirements—effective date: July 1, 2000—are microwave ovens and electric- magnetic cookers. These products are also regulated for use in residential environments. The BSMI has not addressed EMC requirements for medical equipment at this time. A revised version of CNS 13803, referencing CISPR 11:1997, is under consideration. Acknowledgments The authors wish to thank Yung-Chi Tang and Han-Chang Hsieh of BSMI and Roland W. Gubisch, PhD, of Intertek Testing Services NA Inc. for their assistance in the preparation of this article. Michael J. Alvarado and Grace Lin are senior project engineers at Intertek Testing Services NA Inc. (Duluth, GA). They can be reached at malvarado@itsqs.com and glin@itsqs.com, respectively.
Back to 2000 Annual Reference Guide Table of Contents
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