A-C motors for driving oil well pumping units

Many types of a-c motors are used to drive oil well pumping units. The diversity of choice of motors suggests that the various types are equally desirable, but this is not the case. Experience and a more fundamental approach to the evaluation of motors for oil well pumping substantiate the conclusion that 5- to 8-per cent slip motors in a dripproof or protected frame should be purchased for installations where 3-phase power is available. Two-value capacitor-type motors in a dripproof or protected frame are preferred where single-phase power must be used.