Advances in adjustable-frequency ac drive technology have made these drives practical for many applications that were formerly considered the domain of dc drives. Paper machine drives are an important example of these applications. The evaluation of competing drive systems is now more complex. The potential purchaser must choose not only from among competing vendors but also from among competing technologies. This paper discusses many of the considerations for comparing ac and dc drive systems for paper machines. A procedure is presented for making an economic evaluation between the two technologies.
