The renewable energy sources (RESs) high penetration projects as a solution with environmental benefits is changing the traditional power system operation and concept. Also, the transient stability analysis has opened new research trends to guarantee a secure operation. Problems such as frequency fluctuations, decoupling between generator angular speed, network frequency fluctuation and kinetic energy storing absence are the main non-conventional Renewable Energy Sources (RESs) penetration in a power System cases. This paper analyzes short-circuit influence on frequency response, focusing on weak distribution networks as those isolated power grids, to demonstrate phenomenon analysis relevance in frequency stability. As study cases considered a generation outage and a load input in order to analyze the frequency response. The paper carried out a comparison between a frequency response during a generation outage and a short circuit occurrence. In addition, modular value and angle generator terminal voltage affectation by electric arc and network ratio R⁄X, failure type influence in power delivered behavior. Also, the research considered a fault location, arc resistance and load state. The arc resistance definition is an added resistance that appears during failure and influences voltage modulus and angle value results showing that intermittent non-conventional renewable energy sources (RES) participation can lead to frequency fluctuations. The research and study case showed that arc resistance, type of failure, location and loadability determine the influence of frequency response factors in weak power systems.