The induction electric motor develops in transient processes significant sized electromagnetic torques, several times exceeding rated, starting and even maximum ones. These torques are the reason for the occurrence of dangerous mechanical stresses in the elements of the kinematic chain of electromechanical system. They should be considered when assessing the reliability of operation of the electric drive. The nature of the flow of transient processes in the electrical machine often determines the behavior of the entire system, an element of which is the machine. Paper deals with transient processes when starting a powerful electric drive for pump unit. The influence of the supply voltage and the total torque of inertia of the electric drive on arising impact torques and currents and starting time have been investigated.