DOI: https://doi.org/10.32515/2414-3820.2019.49.105-116

Influence of Wear of Bearing Shields on ac Power Coefficient of Ac

Tudor Erhan, Nikolai Korneychuk

About the Authors

Tudor Erhan, Professor, Doctor in Technics (Doctor of Technics Sciences), State Agrarian University of Moldova, Chisinau, Moldova

Nikolai Korneychuk, Professor, PhD in Technics (Candidate of Technics Sciences), State Agrarian University of Moldova, Chisinau, Moldova

Abstract

The aim of the article is to ensure the reliability and durability of the bearing assemblies of electric motors used in electric drives. The solution to this problem is achieved through the timely elimination of defects in the seats under the rolling bearings in the motor shields. The article presents the results of determining the dimensions, tolerances and roughness of the castle and landing surfaces of the bearing shields of electric motors to be restored by electrophysical methods. Plots of wear forms of bearing shields, bearing seats of bearings of rotors of electric motors are revealed and it is established that they depend on the operating mode of the electric motor. It was established that with increasing wear of the bearing shields of the rotors of electric motors from 0.15 to 0.24 mm, the ellipsoidal shape of the total magnetic flux becomes more pronounced. This leads to an increase in the angle of shift between the electrical components, which reduces the power factor of electric motors and efficiency. It has been established that the change in the air gap of asynchronous electric motors as a result of wear of the bearing shields leads to the same consequences. As a result of studies, it was found that the most worn-out elements of electric motors are bearing shields, the wear of which depends on the material from which the bearing shields are made, the operating mode of the electric motor, the type of load on the shaft and the duration of operation. Based on the measurements of various types of bearing shields for electric motors of the 4AC series, the maximum wear sizes were determined, which can be restored by electrophysical methods. It has been established that the maximum wear of cast-iron bearing shields is 0.10-0.15 mm, and that of aluminum - 0.1-0.23 mm.

Keywords

electrophysical recovery methods, wear of parts, electric motors, electric drives, electrical equipment, bearing shields, Power factor Cosφ

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Copyright (c) 2019 Tudor Erhan, Nikolai Korneychuk