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Abstract--This paper discusses some consequences of developments in technologies that may impact the risk of electromagnetic interference and equipment damage despite the equipment complying with the tests according to the product standards. Examples of such technologies are: the change from analogue to digital communication, the fast increase in numbers of power converters having smart switching technology and the use of communication via the power system. The paper discusses upcoming sources of emission, uncertainties in emission level, and changing circumstances. It is shown that it is possible for equipment to remain below the emission limits while at the same time the disturbance level increases beyond what was intended by the standard document. The paper also proposes a framework for addressing the problems due to massive penetration of equipment injecting high-frequency harmonics.

A number of measurements have been performed on a full-scale electric model of a house to examine how end-user equipment affect the impedance in the frequency range 9-95 kHz. It is shown that the impedance level for the grid itself is fairly high and that it decreases when end-user equipment is connected. End-user equipment can be divided in to different categories, loads for which impedance is constant over time (for one cycle) and frequency and loads for which impedance varies over time, frequency or both. The measurements indicate that currents in high frequencies travel between loads at a much higher degree than between the load and the transformer. Index Terms-power quality, electromagnetic compatibility (EMC), electronic loads, harmonic distortion, power-line communication.The financial support from the Swedish Energy Administration is gratefully acknowledged.S.K. Rönnberg and M. Wahlberg are with Skellefteå Kraft Elnät AB, 931 24, Skellefteå, Sweden. M.H.J. Bollen, and C,M. Lundmark are with EMCon-Site, Luleå University of Technology, 931 71, Skellefteå, Sweden. M.H.J. Bollen is also with STRI AB, 771 80, Ludvika, Sweden. communication by the network operator.