Power systems struggle from many effects, causing over-voltages and over-currents. One of these effects is ferroresonance, which is a non-linear phenomenon that occurs when the system is unbalanced. This article focuses on a 380-kV transmission line from Turkey's electrical power network where ferroresonance occurs during a switching operation. The system is first simulated on MATLAB (The MathWorks, Natick, Massachusetts, USA) model, and voltage variations are obtained. Spectral analysis methods are applied to the signal, and the frequency components of the system are examined for ferroresonant conditions. According to the obtained frequency components, the steady-state behavior of the system is explained.