Paper 6: Submerged Motor Drives for Glandless Pumps

Abstract

In view of the environmental operating conditions, special techniques have to be used to permit the manufacture of the submerged type of motor as an industrial proposition. The first choice to be made is that of stator winding conductor insulation, which must be impervious to water, flexible to wind, and have good thermal stability. A thorough survey of the limited materials available for such an application determined that high density polythene, extruded on to a flexible stranded cable, would best meet these requirements. Polythene has a relatively low flow temperature, which may be increased, and the mechanical stability of the cable improved, if it is subjected to irradiation dosage. The cable and the necessary seal termination are subjected to accelerated life testing at operating conditions in static pressure vessels before commitment to production. The concept of the mechanical design calls for the use of small rotating diameters consistent with sound engineering practices. Where possible, rotating surfaces must be smoothed to minimize water turbulence losses.