Direct and soft starts of squirrel-cage induction motor are considered. Operation specificity due to nonsinusoidal supply voltage and equivalent circuit parameters changes due to variable voltage magnitude and frequency as well as magnetic circuit saturation and current displacement in rotor winding are studied. Consumed energy calculations show advantage of frequency converter start. Mathematical models are experimentally confirmed. Stator winding overheating during starts is analyzed. Analysis results of motor vibroacoustic indicators during start are given: vibrovelocity and -acceleration of magnetic origin, vibrovelocity of mechanical origin (radial and axial), ventilating and magnetic noises. Mechanical shaft stiffness indexes, shaft strength and dynamic bearing load are examined and compared at direct and soft starts. It was established that due to soft start at low intensities of the control parameters changes, dynamic bearing load surges can be excluded. Resulting shaft deflection at soft start reduces the stronger, the smaller is the control parameter change intensity.

Automated design optimization of controlled induction motors for a variety of design tasks in two ranges criteria is performed. Design tasks include consideration of both static and dynamic modes. The changes in variable motor parameters according to the selected criteria and design tasks are defined. A modification of the criteria of electric drive given costs is proposed by using of operation significance coefficient. This allows reconciling of the maximum of midrange efficiency and the minimum of mid-range resulted expenses. Analysis of the effect of inflation coefficient on the value of the reduced costs objective function is carried out. The classification of a design range limits applicable to the development of controlled induction motors is offered. The applying of range limitations in the automatic optimization design program of controlled induction motors is described. The use of range limitations affects the results of the design synthesis of controlled induction motors.

Purpose. Development of mathematical models of adjustable electrical drives with high-phase order induction motors for their merits analysis at static and dynamical modes. Methodology. At the mathematical modeling main kinds of physical processes taking place in the high-phase order induction motors are considered: electromagnetic, electromechanical, energetic, thermal, mechanical, vibroacoustic ones. Besides, functional as well as mass, frame and value indicators of frequency converters are taking into account which permits to consider technical and economical aspects of the adjustable induction electrical drives. Creation of high-phase order induction motors' modifications in possible on the base of a stock 3-phase motors of basic design. Polyphase supply of induction motors is guaranteed by a number of the adjustable electrical drives' power circuits. Results. Modelling of a number of adjustable electrical drives with induction motors of different phase number working on the same load by its character, value and required adjustment range is carried out. At the utilization of the family of characteristics including mechanical ones at different adjustment parameters on which loading mechanism's characteristics are superimposed regulation curves representing dependences of electrical, energetic, thermal, mechanical, vibroacoustic quantities on the motors' number of revolutions are obtained. Originality. The proposed complex models of adjustable electrical drives with high-phase order induction motors give a possibility to carry out the grounded choice of the drive's acceptable variant. Besides, they can be used as design models at the development of adjustable highphase order induction motors. Practical value. The investigated change of vibroacoustic indicators at static and dynamical modes has been determined decrease of these indicators in the drives with number of phase exceeding 3. References 10, tables 2, figures 4.

The results of theoretical analysis and experimental investigation of the start of the asynchronous motor ANP71A2U3 with the use of the soft start device ATS 01N21QN are presented. Two modes of operation of the device are considered, providing different start-up

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