METHOD FOR DETERMINATION OF ROTATION RATE OF SUBMERSIBLE ASYNCHRONOUS ELECTRIC MOTORS Russian patent published in 2012 - IPC G01P3/48 

FIELD: electricity.

SUBSTANCE: 4k four-pole magnets with radially magnetised heteropolar zones are arranged on the shaft of the submersible electric motor on dielectric beads positioned on the both butt-end sides of k non-magnetic intermediate bearing of the rotor and having a diameter equal to that of the rotor core assemblies. Two magnets turned towards each other with their analogous poles are mounted on each bead circumferentially, in a diametrically opposite way. All the magnet pairs are oriented in strictly the same direction. During the rotor rotation a frequency sequences of electromotive force pulses are generated in the three-phase winding while a frequency sequences of current pulses are generated in the phases of the power cable feeding the submersible electric motor. With the help of a land-mounted measurement current transformer one performs transformation of the frequency sequences of phase current pulses and the sinusoidal current consumed by the submersible electric motor from three-phase feed voltage. A frequency sequences of voltage pulses proportional to that of phase current pulses is recovered through filtration of the current transformer output voltage with the help of a band pass filter having flange pass bands z-f_mjn and z-f_max. With the help of a voltage comparator and a frequency divider a new sequence of rectangular pulses is formed from the recovered pulse frequency sequence, the rectangular pulses repetition frequency is decreased z times and is equal to the submersible electric motor rotation frequency where z is the number of the stator magnetic conductor slots, f_min and f_max are the maximum and minimum allowable frequencies of the submersible electric motor rotation in the ESP unit.

EFFECT: simplification of measurement and measurement results transfer to the surface.

10 dwg, 6 tbl