Analysis of current transients caused by voltage notches

An analysis of current transients caused by voltage notches in an industrial plant is presented in the paper. The source of current transients in the factory lighting was traced to the operation of the nearby six-pulse AC/DC converter. Because of the short duration of the phenomenon, it was not possible to determine if there is a parallel resonance using a standard power quality analyzer. To determine the nature of the interaction, a measurement was done with a storage oscilloscope, and advanced signal processing was applied to the results. Using this technique, it was possible to exclude the presence of a parallel resonance. It was concluded that the transients are a reaction of lamps to voltage notches in certain working regimes of the six-pulse converter. Possible solutions to the problem are separating the supplies of the converter and the lighting installation, filtering, or adding additional line reactances.