Subcommittees

In general terms this means covering immunity and related questions over the whole frequency range, with subcommittees

• SC 77A dealing with low-frequency phenomena (up to and including 9 kHz),
• SC 77B handling high-frequency continuous and transient phenomena, including electrostatic discharges, for example, and
• SC 77C covering high-power transients such as the EM fields produced by high-altitude nuclear detonations (HEMP).

In addition, TC 77 does produce product-family standards covering low-frequency emissions and, under the coordination of ACEC, may prepare product immunity standards if so requested by a product committee.

EMC and safety

TC 77 covers the safety aspects of electromagnetic compatibility, having what in the IEC is called a horizontal safety function. The committee has also produced a Technical Specification (IEC 61000-1-2) on the methodology for achieving functional safety in an EMC context.

This publication provides guidance to product committees, designers, manufacturers and installers of equipment and systems on how to consider EM disturbances as part of a comprehensive safety analysis. In particular, the work of other IEC safety committees is considered in terms of safety concepts and assessment methods, while at the same time the relevant IEC Basic EMC standards are recommended for use.

Note: IEC 61000-1-2 is a guide providing advice. Safety lies in the scope of the IEC Advisory Committee on Safety (ACOS), which can provide assistance on such matters to the very many TCs that also have safety in their scope.

Growing demand

The direct customers of TC 77 standards are EMC experts and product committees of the IEC - in effect the entire industry manufacturing or using electrical and electronic products. They are therefore not only among the most widely used standards within the IEC but are also becoming so in other international, regional and national standardizing organizations. This in turn means they are increasingly the basis for regional or national EMC regulations.

The need and demand for TC 77's Basic and Generic EMC standards is strongly influenced by new technologies and industry trends that create a more and more 'hostile' EM environment. In particular, the density of electrical, electronic and radio communication equipment operating close to each other is increasing, as is miniaturization, and microelectronics have increasing operating frequencies.

Although the most important standards have been completed in recent years, new trends in technology, as well as the globalization of trade, indicate that the standardization area covered by TC 77 will continue to develop. These trends include:

• the drive to save costs by harmonizing test methods world wide;
• efforts to eliminate barriers to trade by harmonizing EMC requirements;
• the need to ensure that equipment operates reliably despite the increasing likelihood of EM disturbances being present; and
• the need to meet regional regulations such as those arising from the European Union's EMC Directive.