ELECTRIC DRILL FOR OIL AND GAS WELL DRILLING (VARIANTS) Russian patent published in 2008 - IPC E21B4/04 

FIELD: well drilling, particularly borehole drilling rigs secured to treadedly connected pipes to be lowered in wells and provided with electric drives.

SUBSTANCE: electric drill comprises rock-cutting bit, spindle, thrust bearing, electric drive and current supply means, which connects ground-based power source with electric drive. Commutatorless electric DC motor is one provided with switchboard. Control electrodes of switchboard semiconductor switch are linked to outlet chains of rotor position sensors. Power is supplied to rotor from high-frequency alternating voltage source connected to upper current supply end. Lower end of current supply is linked to input chain of rotor position sensor through electric filter including at least one electric condenser. In another embodiment input chain of rotor position sensor is linked to lower end of current supply means through constant voltage support circuit.

EFFECT: increased current supply reliability and possibility to regulate drilling bit speed of rotation.

7 cl, 8 dwg