| Abstract |
A Belgian sheet steel manufacturer has specified a new range of a.c. variable speed drives as part of the upgrading of a discontinuous tandem cold mill (TCM) to a continuous process coupled with the preceding pickle line. The conversion of the TCM required the inclusion of a continuous exit section consisting mainly of d.c. driven tension reels and flying shear. Four quadrant, line regenerative, a.c. vector controlled drives have been selected to meet the performance requirement of the associated pinch, deflector and shape measuring rolls, necessary during an automatic reel changeover at 250 metres per minute and during the rapid controlled stopping duty. The small size of the induction motors, for the required overload torque rating, and the dynamic performance possibilities offered by these latest 4 quadrant drives were factors influencing the choice for this exacting application. The paper will focus on the performance capabilities of induction motors in developing overload torques of many times their full load rating for rapid speed changes. Comparisons will be made between the calculated results from equivalent circuit models of the induction motors and measurements taken from production equipments. A brief description of the other features incorporated into this range of a.c. drives gives an insight into the potential that such products offer for a wide range of high performance applications. |
