This paper considers the polynomial and exponential load models, for the analysis of the parameters behavior, in steady-state perform. The model was made in an electric reference system, in this case 3-Bus system and IEEE 14-Bus system. The development of the analysis is performed to find the cause of the movement, in the load characteristic curve, in order to find the margin of voltage stability. Additionally, this paper considers the limits in voltage established for the country in terms of power quality, to determine the margins of voltage stability and margins of voltage restrictions for a specific load.