Synchronous and slip-ring induction motors drive cement mills

In the process of selecting a suitable motor for a cement mill, there are several issues to consider that, for the purpose of analysis, can be grouped into two distinct categories. The first category is the technical analysis, which is based on engineering considerations that evaluate the merits of either a synchronous or a slip-ring induction motor installation. The second category is the economical analysis, which follows closely the results of the technical evaluation with emphasis on the original investment cost and the cost of operating and maintaining the equipment over its useful lifespan-estimated as 30 years. Among the technical issues, the first should be identifying the torque requirements and initial power system limitations. The choice of motor design will largely depend on these requirements. The other issues relate to electrical energy savings. With the cement mill being the largest single power consumer in the plant, the choice of motor and drive will directly influence these savings, which can be significant. Several cement mill installations in operation today are discussed