Lect6Part2FCC_CE_Limits_10khz_30MHz

Lect6Part2FCC_CE_Limits_10khz_30MHz - 40 EMI Effects of...

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90.-------~~,_'j-.-.---,--~.__,; -,,:7!----~--~~;-,-,~,,----~~ 1 :;;! ! 1 -' ;; 40 EMI Effects of Power Converters 40.7 EMC Standards The number of institutions involved in regulations and rec- ommendations that concern EM! is quite large, and to an average person the issue of EMC· standards can be some- what confusing. EMC is defined as the ability of equipment to function satisfactorily in its electromagnetic environment without introducing intolerable disturbances to anything in that environment. EMC requirements entail two major items: emissions and susceptibility, or its opposition, the immu- nity. Electromagnetic disturbance is any phenomenon that may degrade the performance of a device or system, or adversely affect the living and inert matter. The term "EMf' pertains to that performance degradation. It is worth mention- ing that in the colloquial engineering language, EM! is often meant as emissions and EMC as immunity, which is inexact. In the important U.S. military standard MIL-STD 461; the emissions and immunity requirements are referred to as con- ducted/radiated emissions (CE/RE) and conducted/radiated susceptibility (CS/RS). In the USA, it is the Federal Communication Commission (FCC) that sets the general EMC requirements (medical prod- ucts are regulated by the Food and Drug Administration). The FCC Rules and Regulations, Title 47, Part 15, Subpart B concerns "any unintentional radiator (device or system) that generates and uses timing pulses at a rate in excess of 9000 pulses (cycles) per second and uses digital techniques." Clearly, that mandatory requirement applies to almost every product that 80 : .:. - ... - --~-- 70 - ~60 rn -0 50 --. 40 1117 employs a microprocessor. It is illegal to sell or advertise for sale any product regulated under Part 15, Sub-part B until its emissions have been measured and found to be in compliance. Products regulated by Part 15, Subpart B are divided in two classes. Class A devices are those marketed for use in com- mercial applications, while the domestic applications belong in Class B. As illustrated in Fig. 40.23, Class B limits are more stringent than those for Class A products, and the Class B administrative certification process is more rigorous than the Class A verification process. The American National Standards Institute (ANSI) standard C63.4 defines the required emis- sion test procedures. However, there are no FCC regulations pertaining to product immunity to electromagnetic fields. EMC requirements
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Lect6Part2FCC_CE_Limits_10khz_30MHz - 40 EMI Effects of...

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