John Logi, TRW Reda Pumps
A typical submergible electric pumping unit is composed of seven basic components: electric motor, multi-stage centrifugal pump, protector, power cable, motor flat cable, switchboard and an auto transformer, single three phase or a bank of three single phase transformers. All of the above equipment is manufactured in numerous sizes and types to fit the well specifications, such as casing size, desired producing volume, total lift, electrical power supply and environment. In addition to these basic components, various auxiliary items are used. Some are required, while others are optional. The most common required items to complete an installation are: Cable clamps, cable reel, reel supports, shock absorber, shipping boxes, tubing support and, in many cases, a swage nipple. Other optional items not required for an installation, but recommended where applicable are: Flat cable guards, check valve, bleeder valve, centralizers, motor jackets and downhole pressure sentries. In some instances, usually in remote areas, engine generator sets are used instead of purchased utility power. Such generator sets may power multi-well installations or individual wells. In the latter case, transformers can usually be eliminated by supplying an alternator which is wound to supply the proper input voltage (required surface voltage).