Abstract-One of the most applied electrical machines is Induction Motor (IM) with cage rotor. This type of motors has high starting current and torque value at the accelerating moment. Voltage drops in electrical nets are caused by high currents; therefore, it makes influence on the electrical energy users and electricity supply companies. Use of nowadays semiconductor devices can solve these disadvantages. Despite of the fact the frequency control devices are developing rapidly its application in industry is not so much. In several companies operating with induction motors, control devices are not installed. The aim of this work is to research influence of unbalanced voltage on IM torque. With the help of the program MATLAB Simulink a model which analyzed IM torque was created. In the work process this program was made for conveyors when the load is constant during the operation. At the end of this work, practical measurements are compared with the values obtained in software MATLAB Simulink.