Theoretical determination of individual values of insulation four-element equivalent circuits elements parameters at technical diagnostics of insulation by absorption methods

The aim of this article is to present a methodology of determining of the individual values of the parameters of four-element equivalent circuits for insulation with through conductivity. Methodology. The proposed method consists in the fact that at a time interval of more than 10 s, when the charge indicator no longer contributes to the leakage current, three points [t.sub.1], [t.sub.2] and [t.sub.3] are selected, such that [t.sub.2]--[t.sub.1] = [t.sub.3]--[t.sub.2]. To be able to determine the absorption coefficient [R.sub.60]/[R.sub.15], it is recommended to take [t.sub.1] = 15 s, [t.sub.2] = 37.5 s and [t.sub.3] = 60 s. At the same time, by subtracting I([t.sub.2])--I([t.sub.1]) and I([t.sub.3])--I([t.sub.2]), the constant component of the absorption curve is excluded and it becomes possible to determine the individual values of the parameters of the generalized equivalent circuit of insulation, additionally using its conductivity in operator form. Results. As calculations show, the correct determination of the parameters of insulation equivalent circuit according to the proposed method is possible only with a certain ratio of these parameters. The charge time of the geometric capacitance [C.sub.g]([R.sub.0]+[R.sub.d]), where [R.sub.0] and [R.sub.d] are the resistance that forms the charging exponent, and the resistance of the sensor, should be within 0.2 s