WAY OF CONNECTION OF A THREE-PHASE MOTOR TO A SINGLE-PHASE NETWORK VIA RESONANCE EFFECT

Abstract

In this paper, we propose a method to connect a three-phase motor, with windings connected by a star and a phase-shifting capacitor as the third contact, to a single-phase network, with efficient use of electrical energy due to compensation of reactive power and due to effective distribution of the voltage in front of the motor’s oscillating circuit. A resonance phenomenon in an oscillating circuit of the motor is used to compensate for reactive power, i.e. to increase the active power coefficient to the maximum value. A capacitor bank in front of the circuit is used to effectively distribute the voltage at the input of the motor circuit in order to increase the motor voltage from the mains value of 220 V to the nominal value of a three-phase motor of 380 V. A special installation was created for experimental studies. The results of experimental studies, theoretical calculations of the electrical circuit of the installation, as well as the voltage vector diagram of the motor circuit show that the case when voltages on the motor are U = 380 B (U_L= U_C5= 325.4 B) and U = 392 B (U_L= U_C5= 375.6 B) most closely corresponds to the resonant state of the motor oscillating circuit. The proposed method was introduced into the educational process as a laboratory work for students of technical specialties of the Almaty University of Energy and Communications, and can be used by designers, inventors, scientists and specialists interested in similar issues to create devices that connect a three-phase star-connected motor to a single-phase network.