Europe grapples with electromagnetic compatibility standards for telephony
The European Union`s Electromagnetic Compatibility directive goes into effect on January 1, 1996. Fiber-optic cable, which is neither susceptible to, nor an emitter of, electromagnetic disturbance, is not at issue. However, the directive will affect all the active equipment in telecommunications networks, as well as the cabling.
Under the directive, individual pieces of equipment and entire installations, including cabling, must be tested by an officially recognized laboratory and issued a certificate of conformity. The equipment and the installation must then display the letters "CE" (known as the "CE marking") and indicate the standards to which it complies.
The EMC directive`s impact on prices remains unclear. The additional design considerations and conformity testing will add to the cost of producing certified equipment.
Until the directive goes into effect, national EMC standards apply. These standards, however, vary from country to country. But, once the directive goes into effect, each country must ensure that its national standards conform with the European standards. Enforcement of the standards will remain in the hands of the European Union member states, however.
The manner in which the directive originated differs from previous efforts when the European Parliament in Brussels tried to legislate every detail. The EMC directive falls under what is known as the New Approach. Under this scheme, the Brussels European Parliament votes to adopt a White Paper that incorporates basic criteria of an issue it believes affects the safety of European citizens and the free flow of trade. Once adopted, the text becomes a Directive, which is essentially European law. The European Union then defers to the appropriate standards bodies to develop standards to support the directive.
Cenelec standards body
The official European standards body for the EMC issue is the European Committee for Electrotechnical Standardization, or Cenelec (see page 31). This standards body works closely with its international counterpart, the International Electrotechnical Commission; and with the European Telecommunications Standards Institute, or ETSI. Compliance with standards is voluntary, but it is the best way for manufacturers to ensure they are conforming with the directive.
Cenelec standards that could be used by manufacturers to interpret the directive are cited in the Official Journal. National governments are obliged to harmonize their laws with the official standards. Free trade is ensured, because this harmony eliminates the possibility that one country could set extraordinary standards that would make it difficult for manufacturers to comply and sell their products in such a country.
This is the goal of the EMC directive. However, all the standards that will support the directive are not yet in place, and several special cases need to be defined.
Nevertheless, manufacturers of telecommunications equipment are taking steps to ensure compliance with the directive. The process begins with the initial design of the equipment. At Philips TRT, for example, equipment design engineers are working closely with their quality assurance department. According to Zdenek Picel, who is responsible for transmission equipment development at Philips, "Technicians need the correct interpretation of the requirements--not just in terms of measurement, but in terms of applicability and legal/contractual customer issues."
He explains that fiber-optic-based applications typically have higher operational frequencies, making them more complicated to measure and control. Therefore, the directive requirements have to be taken into account early in the design phase. To comply with these requirements in a cost-effective way, EMC considerations on the component and circuit-board levels are extremely important during the development phase.
However, performance benefits accrue by controlling all electromagnetic disturbances; equipment such as multiplexers, crossconnects and synchronous digital hierarchy line equipment can be stacked without introducing interference conflicts.
Philips has made a multimillion-dollar investment in in-house testing. Picel claims the company can test an entire installation, including the cabling.
Alcatel Bell, which is also involved in testing, has a laboratory in Belgium that can issue to other vendors certificates of conformity with the directive. Jeroen Ijsseldijk, quality manager, says an entire installation must be certified, but some questions regarding what constitutes a system need to be answered. For example, some companies argue that if the power supply is a separate unit, it should be certified separately. Standards will be needed to clarify this issue.
Ijsseldijk points out that original equipment manufacturers and system integrators are responsible for certifying the compliance of the systems they install, even if the various units come from different manufacturers. This compliance issue raises the question of whether a unit of equipment is standalone (in which case it must be CE-marked indicating conformity) or whether the unit is to be integrated into a system (in which case the entire system must carry the CE marking). In the latter case, the individual units may or may not be certified. q
Adele Hars writes from Paris.