Electrical Design Considerations for Drilling Rigs

The following considerations in the selection and design of electrical apparatus for oil and gas well drilling rigs are discussed: 1) general rig environment and geographical environmental effects; 2) selection and/or verification of drilling motor torque requirements for draw works, rotary table, and pumps; 3) four quadrant (speed-torque) analysis for draw works and rotary table; 4) merits of application of three types of adjustable speed drives (Ward-Leonard, thyristor type dc converters and adjustable frequency inverters); and 5) general power distribution considerations such as generating capacity, voltage selection, fault calculations, system grounding, voltage and frequency dip, power factor, and harmonic currents.