For evaluating quality of electrical insulation, it is necessary to measure the property of insulators. Dielectric constant and loss tangent (tans) are two important parameters for determining the property of insulator. The measurement of above parameters is normally based on the time- domain and frequency-domain, which is costly and time consuming.
In this study a multiple-frequency binary sequence signal was applied to the specimen, which is a periodic voltage that switches rapidly between two presets values. Since the applied voltage is periodic, therefore the results are obtained by using a numerical Fourier series analysis. The difficulties associated with Fourier transform are avoided. By applying the above method, capacitance (dielectric constant) and loss tangent is measured over a wide range of frequency.