Variable-Voltage Equipment for Rotary Drilling Rigs

Compared to a mechanical drive, the d-c variable-voltage transmission has several important advantages. These are: 1. Loads may be picked up smoothly and handled smoothly over a wide range of controlled speeds. 2. Flexibility as to: location of equipment; number, type, and capacity of prime movers; and combining of two equipments. 3. Lower maintenance of power plant and transmission due to elimination of abuses incident to clutch manipulation. 4. More continuous drilling due to elimination of delays incident to clutch manipulation, to inherent operating characteristics, and to less time out for repairs. In view of such advantages drilling costs should be less.