AC paper machines drives - Did they meet expectations?

Two developments made high performance ac drives a reality. The first development was the advent of microprocessors capable of real time parameter calculations for the field orientation theory formulas. The second development was the introduction of power devices able to switch power on and off at high frequencies. New technology had to be accepted. Key mill personnel had to be identified and convinced that the ac drive equipment would perform as well as, and be as reliable as, the existing de drive equipment. The cost of new technology was higher because low production volume contributed to higher manufacturing costs, and a portion of the expenses for research and development had to be recouped on the first product offers. The benefits of the new technology had to be determined so the additional capital expenditure could be justified. Presented in this paper is the review process used at the time to convince mill personnel that an ac drive would work and would be reliable. Upper management was convinced that the extra cost for an ac drive was justifiable. The first ac drive was approved and installed at the P.H.Glatfelter Company in the Spring Grove, PA mill on #7 paper machine during 1988. The successful installation of the first ac drive on #7 PM resulted in the installation of coordinated ac drive systems on other paper machines and converting equipment. The experience gained while installing other coordinated ac drives is also included.