Power quality and line considerations for variable speed AC drives

Variable speed AC drives are finding their way into all types of industrial and commercial power system applications. Their application to the load (motor) generally is reasonably well selected-at least within heavy industry. However, there are many line (source) design parameters learned in the 1950s and 1960s which are now being frequently overlooked. This paper represents many years of experience doing power quality investigations. The authors combined this experience with more recent technology and discuss some of the areas of concern which frequently result in serious performance or power quality problems. These areas include commutation notching, electrical noise, harmonics, power factor and earthing. Finally, basic design guidelines are given to greatly minimize system problems-especially as newer technologies are intermixed with old