Four CATERPILAR 3512B diesel engine generator sets are combined to generate 3 phase 600V 50Hz alternating current, which is not only supplied for six SCR cubicles, but also for 380V MCC system via 1250KVA main transformer. After rectified by SCR cubicles, 3 phase 600V 50Hz alternating current changes to 0-750V (adjustable) direct current, and then drives DC motors of drawworks, rotary table, and mud pumps. The drawworks is driven by two DC motors; the rotary table is driven by one DC motor; and each mud pump is driven by two DC motors. "K" type mast and slingshot type substructure. The mast and substructure are installed on the ground and then raised by drawworks. The drawworks adopts hydraulic disc brake as main brake and water-cooling electromagnetic eddy current brake as auxiliary brake. The mud pumps use narrow V-belt transmission.