Effect of voltage harmonics on the operation of solid state relays in industrial applications

The results of a study on the effects of voltage and current harmonics on the operation of four types of solid state relays (SSR) used in control schemes of many industrial applications are presented. This study started after repeated malfunctions of electrophotographic printers in some data processing centers. The misoperation of zero switching solid state relays was suspected as the cause of the malfunction. Tests on the SSRs were performed using a single phase harmonic generator and a digital oscilloscope with signal processing software capabilities. The results indicate that voltage harmonic distortion may cause a delay in the turn-on time of more than a cycle. In some cases, complete failure to turn on or off may occur. Recommendations to reduce the impact of harmonic distortion on these types of relays are discussed.<>