Actual recent blackouts which were charactherized by voltage sags suggest that normal process for the voltage control can aggravate the voltage level. It happens because, in special situations, the automatic voltage control has the opposite effect of its logic of conception. In order to identify situations like those, we developed a computational tool to evaluate the effect of voltage control based on the linearized system of power flow equations and selected control equations. The tool calculates the voltage control sensitivity matrix which relates the controlling variables and the controlled voltages of voltage control equipments. The voltage control on synchronous generators is performed by automatic voltage regulators (AVR) that, in practice, have no control logic to differentiate direct and inverse relation between the controlling variable and the excitation voltage of generator. Therefore, if the relation is inverse, the result of the action of the AVR is inadequate (opposite to desired) and may lead the system to collapse due to low voltage, for example. Hence, this paper presents a process to achieve the new voltage profile, starting from operating points with adequacy problems of voltage control actions, through appropriate changes in variables of generators determined by analysis in voltage control sensitivity matrix.