"ANALYSIS OF A TUBE-MILL INDUCTION MOTOR DRIVE FED FROM CYCLOCONVERTER

Abstract

A tube mill is employed in cement plants for crushing the raw material (i.e.- lime stone, sand stone, hematite and coal) and clinkers. The mill which is tubular in appearance is driven at a very low speed of the order of 15 rpm by a motor through reduction gears. Such drivers are built in large power ratings, the highest reported in literature being 15000 hp. A gearless tube mill drive employs a cycloconverter between supply mains and the motor for reducing the supply frequency to a very low value. When run on this supply the motor delivers the desired low speed, obviating the need of reduction gears. In present work an attempt is made to simulate a gearless tube mill drive. Performance characteristics are computed of a realistic 3600 kW tube mill drive under steady state. The computed results are presented and discussed,