Method for determining the power of squirrel-cage induction motors

Squirrel-cage induction motors are the main type of electric motors used for the electric motor drive of the working mechanism of industrial processes. The task of the electrical service of the enterprise is to control the engine power during operation and to prevent overloads or inefficient operations. In order to do that a non-contact method for determining the power of squirrel-cage induction motors is proposed. The method is based on the property of the mechanical characteristics of an induction motor, when with increasing the moment of resistance on the drive shaft, the rotor speed decreases in proportion to the load. Therefore, by measuring the rotor speed of the engine, it is possible to judge the degree of its load. To confirm this, experimental studies of axial fans were carried out. Linear supply voltage, winding current, active power, power factor and engine speed were used as the analyzed parameters of the motors. For more information about the state of the motor, in addition to analyzing the stator current, an analysis of the frequency of the supply voltage, as well as the input power, which is directly related to the current and supply voltage, was made. In the course of the experiments, a number of functional dependences of engine performance on its speed were obtained. It was established that tests are necessary for not only repaired engines, but also new ones to determine the optimal modes of its operation and identify production defects.