An Influence of Operating Medium Temperature Change on Characteristics of Electric Motor for Borehole Investigating Devices

Abstract

The extraordinary conditions for borehole motors are following: the operating medium temperature changing interval is from –20oC up to +250oC; the hydrostatic pressure changes from atmospheric up to 210 MPa; the operating medium – dielectric liquid; an energy source is of limited power; the length of geophysical cable is up to 10000 m; the load during the operating cycle is non-constant. These conditions have influence on the motor reliable operating, maximum power transmission, changing of characteristics. The critical slip and maximum electromagnetic power of the induction motor with solid ferromagnetic rotor supplied through the long geophysical cable taking into account the parameters of the motor and supply circuit have been derived. The algorithm and program for study of the borehole motor characteristics taking into account the wide temperature change interval of the borehole operating medium and it’s influence to the parameters of motor and geophysical cable while the cable lengths on the ground surface and let down in borehole are different has been developed. Ill.1, bibl. 7 (in English; summaries in Lithuanian, English and Russian).