METHOD FOR IDENTIFICATION OF BREAKS OF RODS OF SQUIRREL-CAGE WINDING OF THE ROTOR OF THE ASYNCHRONOUS ELECTRIC MOTOR AND THEIR QUANTITIES Russian patent published in 2018 - IPC G01R31/34 

FIELD: electrical equipment.

SUBSTANCE: invention relates to electrical measuring equipment and can be used to determine the technical state of squirrel-cage windings of rotors of asynchronous electric motors. Radial component of the induction of the external magnetic field is recorded by a sensor which is mounted on the motor housing in the region of the middle of the length of the stator core. Registered signal is differentiated. Amplitude spectrum of the received signal is formed. Value of the mains frequency and slip of the induction motor are determined. According to the received values of mains frequency and slip, the lower and upper side frequencies of the harmonics from the fictitious winding of the rotor are determined, excluding the upper side frequency of the harmonics of the fictitious winding of the rotor, the sequence of which is equal to the number of pole pairs of the motor. Complex amplitudes of these harmonics of the fictitious winding of the rotor with the lower and upper side frequencies are determined. Complex amplitudes are transformed into new complex amplitudes by multiplying them by the predetermined complex attenuation coefficients of these harmonics from the fictitious winding of the rotor with the lower and upper side frequencies. From the new complex amplitudes and frequencies of the lower and upper side frequencies of harmonics from the fictitious winding of the rotor, diagnostic signal of the required duration is formed by means of inverse Fourier transform. Received signal is rectified, divided into signals with the same duration equal to the period of rotation of the rotor. Arithmetic mean of the sum of the instantaneous values of these signals is computed at the corresponding times of the separated signal is computed and average signal with a duration equal to the period of rotor rotation is formed. Presence of statistically significant peaks is determined in the averaged signal. Number of broken rods of the rotor winding is determined by their presence and quantity.

EFFECT: increase in the reliability of detection of rod breaks, simplification and reduction of labor intensity.

1 cl, 4 dwg