Characterization of EMI/RFI in Commercial and Industrial Electrical Systems

In this paper, experimental tests have been carried out to collect and analyze Electromagnetic Interference / Radiofrequency Interference (EMI/RFI) generated by variety of industrial equipment and electrical arcs in different settings. The EMI/RFI intensities were measured and compared to those with series arcing present. Test results show that in general, variable frequency drives and power quality products generate strong EMI/RFI at frequencies below 1MHz. In particular, the EMI/RFI upstream of a variable speed motor drive is consistently higher than those induced by other loads. As frequency increases, intensities of these signals tend to decrease due to strong signal attenuation from filters formed by distributed capacitances and inductances, and transmission line effects that become dominant with long cable lengths for the measured circuits. Similar to Arc Fault Circuit Interrupter (AFCI) technology for residential breakers, these results may be used to gain a better understanding of the EMI/RFI characteristics for developing AFCI technology for commercial and industrial applications.