DEVICE FOR DETERMINING ROTATION SPEED OF INDUCTION MOTOR ROTORS Russian patent published in 2017 - IPC G01P3/48 

FIELD: electricity.

SUBSTANCE: voltage and current sensors generate signals proportional, respectively, to the current and voltage of one phase of a rotor of the induction motor. The first and second low-pass filters perform the functions of anti-aliasing filters, cutting off interfering higher harmonics in signals proportional to the current and voltage of one phase of the stator. The sequence of digitized data from the outputs of the first and second analog-to-digital converters goes to the input of the spectrum analyzers, which give spectra of voltage and current signals at the output. A characteristic harmonics calculator isolates the main and characteristic harmonics of the voltage. The engine type selector sets the motor type for the motor parameter base, which stores the engine design parameters, i.e. the rated power P_nom, the number of rods of the rotor R, the value of the nominal slip s_nom, the number of pairs of poles p. If there is no engine type entered in the database, it is entered manually. The power calculator calculates the amount of the electric power consumed by the motor that is used to select the slot harmonics search corridor and determine the rotation speed of the rotor in the speed calculator. In addition, a power consumption detector, an engine type selector and a motor parameters database, containing the engine design data, are introduced, which reduces the complexity of the frequency determination process.

EFFECT: increased level of automation.

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