Characteristics of flicker depending on network loads

Peculiarities of different kinds of load in relation to produced flicker effects are presented in the paper. The analysis bases on the measurements performed in low voltage installations of an industrial object using a conventional power quality instrument. Selected types of the load: laser-cutting machines, welding devices and electrical drives were chosen in order to observe the specific properties of flicker produced in these circuits. Some differences of short-time flicker severity in relation to load type were exposed and discussed. Unfortunately, during measurements it was not possible to separate the influences of other load in the analysed network, so the observed voltage was disturbed by the selected load as well as partially by other devices supplied from the same network. However, the specific peculiarities of analysed load were observed and discussed. Furthermore, the measured values of the short-term flicker severity, registered according to the standard EN-61000-4-15 was compared with the ratio of the voltage changes in the network. Based on these observations some critical evaluation of obtained measuring results in relation to the physical sense of flicker effects were discussed. The analysed load was characterised by current flow as well as the number of changes in a given time interval. The obtained results, after a more detailed analysis could be used in the future for identification of the disturbance sources in the network.