Design Features

Learn to live with the European EMC Directive (it won't go away)

Dan Strassberg, Senior Technical Editor

 The EMC Directive embodies some sound ideas.
Unfortunately, it also involves a Byzantine and quintessentially Old World bureaucracy.

More than one wag has ruefully quipped that, in the European Union's (EU's) Electromagnetic-Compatibility (EMC) directive, "EMC" stands for "eliminate minor competitors." The directive, which went into effect at the beginning of this year, requires companies worldwide to generate and maintain files that contain lots of paperwork.

  In the European Economic Area (EEA), which comprises nearly all of Western Europe, completion of this paperwork has become a prerequisite for manufacturers' being able to continue to sell electronic end products. The requirement affects not only manufacturers, but also their European distributors and sales agents. In small companies, the mandated paperwork and the cost of the consultant and test-lab services that often become necessary can be burdensome.

  The stated motivation for the EMC Directive and related EU directives (formerly European Commission—EC—directives) is reasonable: When a user employs products in a way a seller describes as appropriate, products should be able to safely perform their intended functions. A purchaser should not have to demonstrate the suitability of a product that a vendor implies will work in a particular application. The directives' basic implementation philosophy is not new: EU directives indirectly establish performance standards and require that manufacturers be able to demonstrate that products conform to those standards.

  In most developed countries, similar regulatory philosophies have existed for generations. In many places in the United States, various standards of Underwriters' Laboratories (UL) play roles somewhat like that of EU directives. Many local building codes require a UL mark on certain types of products that contractors install in buildings.

  The major differences between UL and its standards and the EU and its directives are the following: UL is a private organization; the EU is a quasi-governmental body. UL standards often dictate methods of construction; EU directives and the specifications to which they refer rarely do so. UL inspects and tests products before approving or recognizing them; the EU does not, although manufacturers often choose to submit products for testing by EU-accredited bodies as a way of demonstrating compliance with EU directives. Finally, UL standards do not apply to EMC, whereas the EU EMC Directive effectively mandates compliance with several EMC specifications.

  The US Federal Communications Commission's (FCC's) RF-emissions requirements parallel the EMC Directive (Tables 1 and 2). For several years, the FCC has required manufacturers of many electronic products to demonstrate that their products meet FCC guidelines for radiated and conducted EMI. Manufacturers can legally sell products in the United States only if those products comply with the applicable regulations. Manufacturers indicate compliance by displaying a registration number on the product or in the accompanying documentation.

  Like the FCC regulations, the EMC Directive requires that commercial products comply with conducted- and radiated-emissions standards. The requirements of the FCC and the EU differ in the area of EMI immunity (Table 3). FCC regulations do not deal with EMI immunity, but the EMC Directive covers products' susceptibility to several types of EMI phenomena. EMI can enter a product through the air, via power or signal lines, or—in the case of ESD—through operator contact. Before the EMC Directive, most companies that concerned themselves with their products' EMI immunity or susceptibility were in avionics or military electronics.

  The EMC Directive targets immunity from ESD; RF-radiated interference (RFRI); RF-conducted interference (RFCI), which enters products via power and signal lines; electrical surges, usually resulting from lightning strikes to power or telephone lines; and electrical fast transients (EFTs), or bursts, which usually result from arcing of switch contacts that open while current is flowing.

  Immunity testing is unusual in that, in many cases, it permits the product manufacturer to select the failure criteria. Sometimes, the manufacturer can even say that a product has passed if it becomes inoperable and the purchaser must return it to an authorized facility for repair. Such behavior might be acceptable in a small appliance subjected to a line-voltage-surge test. A product that becomes hazardous to touch after a surge test definitely fails the test, however. Moreover, the manufacturer must apply a standardized definition of "hazardous."

  Manufacturers of certain types of equipment, such as patient-data-management systems for hospitals, have little latitude in determining what constitutes a failure, however. For example, if such a system undergoes an ESD test and drops a bit that indicates that a patient is allergic to certain antibiotics, the manufacturer cannot describe the behavior as acceptable.

  Thanks to the EMC Directive and related EU directives, many design and quality-assurance engineers have begun to become familiar with a bewildering array of acronyms and document numbers. Many of these documents are European Norms (ENs). Others are specifications of the International Electrotechnical Commission (IEC). Many ENs reference IEC specs.

  Even more baffling than the terminology—at least at first—are the procedures that companies must follow to comply with EU directives. Manufacturers certify a product's compliance by affixing the CE Mark to it (Figure 1). If a product is too small to accommodate the mark, it can appear in the product's manual.

What the CE Mark means

  The CE Mark means that an importer or a manufacturer declares that its products comply with the portions of the EU's Marking Directive that apply to products in a particular class. Unlike the marks of organizations such as the Canadian Standards Association or UL, the CE Mark indicates neither that any government or private body has tested the product nor that the product is designed or manufactured in accordance with any standards. For example, the Mark can appear on products manufactured in facilities that do not comply with ISO 9000-series documents.

  One method—often the least painful one—of demonstrating compliance is via an "EU Declaration of Conformity" (Figure 2). This document, a copy of which usually appears in the product manual, lists the EU directives and ENs with which, according to the manufacturer, the product conforms. The document also indicates where and under whose custody the manufacturer maintains the files of supporting documentation.

  A manufacturer can also meet the requirements of the EMC Directive by having a "competent body" (CB) or a "notified body" (NB) conduct product tests. CBs are testing laboratories that appropriate authorities in Europe accredit. CBs must maintain headquarters in Europe, although CBs can and do test products outside Europe—either in facilities they maintain elsewhere or at facilities of affiliated non-European labs. Besides headquarters location, CBs must meet several requirements, including possession of adequate civil-liability insurance. NBs and CBs are similar, except that national authorities appoint NBs and notify the EU of the appointment.

  National authorities can accredit equipment manufacturers' laboratories as CBs, provided that the manufacturer satisfies the accrediting authorities that those responsible for shipping products do not influence laboratory officials' judgment (Reference 2). In theory at least, a US laboratory that a European-headquartered affiliate or subsidiary of a US company operates could receive accreditation as a CB. This laboratory could test products that the parent company designs and manufactures in the United States.

Technical Construction File

  The final route for demonstrating conformance is the Technical Construction File (TCF). The EMC Directive sets forth conditions under which a manufacturer might choose to satisfy EMC requirements via a TCF. A CB must certify a TCF or must produce a report that supports the TCF. Even so, the TCF need not—but may—contain test data.

  Manufacturers of highly configurable products often choose the TCF route, because testing of all possible product configurations is impractical. The TCF must explain the rationale for the protocol the manufacturer uses to assure conformance. If testing is part of the protocol, the TCF must explain to the CB's satisfaction why the protocol's limited tests are adequate to assure the conformance of all configurations.

  Electronic products fall under the EMC and Low-Voltage (LV) directives. The LV Directive covers electrical safety. Electromechanical products, such as printers and copiers, fall under the LV and Machinery directives as well as the EMC directive. The EMC, LV, and Machinery directives exemplify "'horizontal" directives, because they are not application-specific. Other directives, such as the Medical Device Directive, apply to products for vertical markets.

  Authorities in any European country who determine that a CE-marked product fails to comply with applicable directives can halt the sale or distribution of the product throughout the EEA. Moreover, if the authorities determine that willful mismarking took place, they can prosecute the manufacturer, or, in the case of products manufactured by companies outside Europe, the importer. Many observers describe this arrangement as "self-policing." Unless they have something to hide themselves, many companies are only too happy to inform the authorities of their competitors' violations.

  Labeling on products that bear the CE Mark or documentation accompanying such products should indicate the year in which the manufacturer affixed the CE Mark. (The year of marking was once part of the Mark, but this situation has changed.) If this date is absent, customs inspectors can assume that the importer or manufacturer represents the product as complying with all directives that apply to products of the appropriate class on the date of the customs inspection. The inspection can occur long after application of the CE Mark. So, manufacturers and importers of products whose documentation or labeling fails to indicate when the CE Mark was affixed might be responsible for some expensive retrofits or upgrades.

  On electronic end products, a CE Mark affixed in 1997 or later indicates compliance with both the LV and EMC Directives. Since 1973, electronic end products sold in Europe have had to meet the LV Directive. Compliance was the responsibility of laws and enforcement agencies in each country, however. Beginning next year, manufacturers will certify a product's LV compliance by affixing the CE Mark.

  Even though a product already complies with the LV Directive, the manufacturer or importer cannot legally imply compliance with 1997 marking requirements until 1997. Manufacturers also cannot legally place a CE Mark on an item that is not an end product. Determining which products should carry the CE Mark is difficult, however.

  For example, power-supply manufacturers erroneously place the CE Mark on supplies used in desktop PCs, according to Darren McCarthy, R&D project manager for EMC and Spectrum-Measurement Systems at Hewlett-Packard (Santa Rosa, CA). These companies risk penalties because PC supplies "perform no intrinsic function," he says, except as part of PCs or other equipment having similar power requirements. According to McCarthy, only products that perform an intrinsic function should carry the CE Mark.

  Although exceptions exist, someone who buys a PC power supply by itself and not as part of a larger product normally isn't the final purchaser. Usually, the final buyer is someone who buys a PC or who has a repair shop install the power supply as a replacement. On the other hand, an adjustable-output benchtop power supply for lab use performs an intrinsic function and needs a CE Mark.

  Sometimes, consumers play the role of system integrators—for example, when they buy printers for attachment to previously purchased PCs. Therefore, the EU views PC printers as performing an intrinsic function and requires them to carry the CE Mark. Occasionally, standard printers become part of systems in patient-connected medical applications, however. Such equipment must meet the more stringent requirements, including stricter EMC requirements, of the Medical Device Directive. Therefore, a printer manufacturer may find it worthwhile to qualify PC printers as medical devices.

  Companies typically view the CE Mark as good advertising. Although the EU does not intend the Mark to indicate product quality, the Mark indicates exactly that to many misinformed purchasers. Therefore, companies risk marking ineligible products. The penalties for marking a product that performs no intrinsic function are relatively minor. Moreover, so many gray areas exist, company officials feel that, if challenged, they can persuade the authorities that their products do perform an intrinsic function.

  Those familiar with both the EMC and CE marking directives assert that the Marking Directive presents a greater set of problems for compliance and quality-assurance engineers: The Marking Directive is broad, and its scope continues to increase. Keeping abreast of the changing marking requirements for various product classes presents a constant challenge. However, just keeping up with EMC specifications also poses a challenge. For example, the IEC1000-4 series, which covers test-and-measurement techniques for EMC immunity of electrical and electronic equipment, now includes approximately 28 specifications. The EMC Directive will eventually reference many of them.

^References

1. Mertel, Herbert K, "The EMC Directive revisited," Interference Technology Engineers' Master, 1996 Edition, pg 66, R&B Associates, West Conshohocken, PA.
2. Williams, T, EMC for Product Designers, Second Edition, Reed Educational and Professional Publishing Ltd, Boston, 1996, ISBN 0 7506 2466 3.
3. Gerke, Daryl, and Bill Kimmel, "Designer's Guide to Electromagnetic Compatibility," supplement to EDN, Jan 20, 1994.
4. Compliance Design Inc, Handbook of EU EMC Compliance, 1995 Edition, Boxborough, MA.

You can reach Senior Technical Editor Dan Strassberg at (617) 558-4205, fax (617) 558-4470, email ednstrassberg@cahners.com

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