Influence of AC Power Supply on Light Flicker Measurements

Accurate measurement of the short-term flicker indicator is important for avoiding visible flicker and for SSL products to comply with regulations. The IC2023 Interlaboratory Comparison of temporal light modulation measurements revealed large variations depending on the laboratory-grade AC power supplies used. A technical study using a halogen lamp was carried out, resulting in 45 measurements covering 19 different manufacturers of AC power supplies. It demonstrated large differences of measured values of more than one order of magnitude and a correlation with low frequency components is found. A new method to estimate the low frequency noise of a specific power supply and its influence on the measured short term flicker indicator is proposed. Setting a limit for this of 0.03 would make 50% of the power supplies in our sample fail. Laboratories can use this method to evaluate the suitability of their specific AC power supply, to determine their influence on short term flicker indicator measurements, and to support measurement uncertainty estimation.