SUMMARY

In line with the EU EMC Directive in 1996 there have in the last ten years been a lot of standardisation activities in the field of electromagnetic compatibility (EMC). Most of those activities have been related to emission and immunity regarding low voltage equipment for domestic or industrial use. Some work has also been done regarding immunity requirements for equipment in high voltage power stations and substations. Very little has been done regarding how to specify and verify emission requirements from high voltage substations, especially when power electronic equipment is involved. The characteristics of radio interference (RI) from high voltage lines due to corona are well known and documented in the CISPR 18 series. The less well-known characteristics of RI due to sparks are also indicated in the CISPR 18 series. During the past decades a third source of RI has become more and more important, i.e. power electronic equipment. The characteristics of RI from large power electronic equipment can be very different depending on system design and type of semiconductor elements used. For controlling the RI emission, both the formulation of the requirements and the methodology for verification measurements have to be reconsidered. Regarding RI from power electronics it is not sufficient to measure the emission at 0.5 MHz, as is sometimes done for controlling RI due to corona. The complete frequency range of interest has to be scanned