The electrical control system of land and offshore rigs is divided into DC control system and AC variable frequency control system.

The 4000~9000m DC control system is an important part of electric driller. Composed of five parts, namely the diesel engine control unit, DC drive and control unit, driller operation and control unit, electromagnetic brake control unit and AC motor control center, this system can rectify 600V AC voltage into 0~750V continuously adjustable DC voltage, realize step speed regulation and drive of DC motor, and switch between different assignment relationships by logic control of DC contactor. It is high in efficiency, stable in operation, sound in dynamic performance, balanced in loading, simple for operation, complete in display, and perfect in safety protection.
    Diesel engine control unit and AC motor control center of the 3000~12000m AC variable frequency control system is partially the same with that of the 4000~9000m DC control system. The main motor drive and control part adopts advanced full-digital variable frequency speed regulation and DC chopping technologies to improve the speed regulation performance of motor and make it easy for system operation and control; in addition, a high power factor is provided within the range of speed regulation to raise the service power of diesel generator and save energy.