Large Fan Drives in Cement Plants

The various mechanical and electrical considerations in the selection of large fan drives are discussed. First there is a review of different types of fans, their special characteristics, and the methods of controlling the air volume. The discussion then proceeds to the two basic types of fan drives: constant-speed direct motor drives and variable-speed coupling drives. The direct drives include the squirrel-cage induction motors, wound-rotor motors, and synchronous motors. Considerable detail is given on heat losses and temperature conditions resulting from the load torque, accelerating torque, and terminal voltage during starting period. Remedial measures are offered to the motor designer and electrical engineer so that a special motor may be designed for a specific electrical system. Stress is placed on the importance of joint efforts by the motor designer, electrical engineer, and mechanical engineer in selecting a drive system with sound engineering and economics.