The urgency of the discussed issue is caused by the necessity of selecting the most optimal switch from the point of view of the fullness of the high-frequency components. The main aim of the study: to develop the technique for comparing pulses at the output of nanosecond pulses generator to determine the most appropriate switch for sensing the mechanical condition of windings of power transformers. The methods used in the study: for objective comparison of the obtained pulses the authors applied the method of fast discrete Fourier analysis in MathCAD. Method validation consists in the fat that the discrete Fourier transform allows obtaining the necessary results quickly and accurately. The results: the authors found the optimum number of harmonics for initial pulse to be laid out. The authors selected the criterion by which one can judge what switch is the most appropriate to be used in generators for sensing the mechanical condition of power transformer windings. The paper introduces the technique for analyzing and comparing nanosecond pulses at the generator output.