Alignment and maintenance of proper air gap is critical to proper operation and effects motor efficiency. Any required maintenance and repair is typically beyond the scope of conventional maintenance personnel. Difficult liner bolt accessibility in some circumstances. Unexplainable electrical control reactions in other plant equipment. Larger trunnion bearings required because of the additional weight of the motor.
Spare parts are less costly.
Proven reliability with thousands of drives operating successfully. Present size capabilities to 20,000 Hp without exceeding normal gear design allowables. Equipment serviceable by conventional personnel. Installation is much simpler and less expensive than a gearless system. Inching operation is extremely simple to perform and cost effective.