Light Flicker: Theoretical and Metrological Aspects

The quality of the electrical power supply is increasingly becoming a central topic of discussion. The interference sources in the mains are caused by electronic power control with non-linear components that are used more frequently (e.g. PCs and industrial systems with speedcontrolled drives), also in domestic appliances (e.g. television sets, economy lamps). High order harmonics, interharmonics, voltage fluctuations and high frequency disturbances with slewrates of some microseconds or less can be mentioned as examples. In some cases the frequency and width of these voltage variations can produce a physiological irritating phenomenon due to luminance fluctuations of the lighting (flicker effect). These electromagnetic disturbances can cover a large interval of frequencies and can be present in industrial, domestic as well as commercial systems. Therefore in the last years the monitoring of the quality of supply networks has become an issue of international interest. This paper examines the phenomenon of light flicker from theoretical and metrological point of view. Then, a low-cost distributed measurement system, which allows power supply quality to be monitored in large industrial environments, is proposed. The paper also presents the results obtained for the