The paper we presents mathematical model for analysis of transitional processes in three-phase induction motor, that is, wave forms of currents and voltages in time domain and phase coordinates. Model is suitable for relay protection of the motor from disturbances and for estimation of electrical energy quality in the distribution network. New constructions of induction motors present more progressive technical solutions comparing with classical variants and reliable entity only within selected system of protection from expected disturbances (failures and disorders followed by asymmetries). Measuring process is not required due to application of simulation in selected MATLAB package.

The document illustrates the methods and algorithms for calculation of overvoltage at the power transformer excerpts during the activation of inductive consumer to secondary transformer. Characteristic stages are activation of the primary phase and followed by two other phases. The new specific condition occurs during the activation of each phase which is presented by alternative electric circuit and simplified equivalent scheme that is used to calculate the values and evaluate overvoltage. For selected parameters of the transformer and inductive loads, the simulation is performed with chosen MATLAB software package.

The paper is presenting theoretical analytical model and computer simulation of electromagnetic transient process in a transformer. Transformer parameters in a selected transitional process have been analyzed. Theoretical model refers to an energetic transformer with concentrated parameters with consideration of parameters of mutual inductance M. Simulation was performed on a personal computer using the software program MATLAB SIMULINK. The computer simulation confirmed the possibility of transitional process analysis in transformer’s windings with concentrated parameters.