In this work, firstly a simulation model has been developed to increases the energy security to load side, and for the characterization and harmonic analysis of the load voltage during the condition of the faults. For this, primary line, backup line and MOSFET have been considered in this model. The MOSFET is used in the model to transfer the control from primary to backup line automatically under the condition of the fault and then automatically switching it back once the fault is cleared. A hybrid method has also been developed, considering the RMS of the Fundamental component of voltage, at each instant i.e. 200 samples/cycle, for the detection of magnitude of faults and for the estimation of the fault durations. It is shown that the proposed hybrid approach is proficient in the detection of fault and estimates the fault duration without producing any error. In addition to this the estimation of duration, time of occurrence and magnitude of harmonics are relatively compared with the event of voltage interruption using the proposed hybrid method and MATLAB’s FFT tool.