Voltage dips cause problems with digital flickermeters

Digital flickermeters often indicate flicker levels that are inconsistent with each other or too high compared with visual observations. In order to learn the reasons for this, some power quality analysers that include flicker measurements were compared in laboratory tests. Also the flicker measurement method of the IEC 61000-4-15 standard was simulated. It showed that even very short voltage dips and interruptions cause inconsistent and very high readings in the compared meters. In the simulations it was possible to remove the problem by limiting the internal variables of the method to a small range. The standard does not define the range of these internal variables but describes flickermeters with analogue filters. Later digital implementation enabled large variable ranges, which led to increased sensitivity to dips. The readings of the compared digital flickermeters are rather misleading in the presence of voltage dips and interruptions. Solutions to this problem are considered.