“…In the IS, it is manifested by significant changes in measured electrical capacity in the function of frequency, while such changes do not occur in a real parallel resistor/capacitor circuit. The CPE models the phenomenon of variable capacitance much better than the capacitor; hence it can be found in oil studies together with at least a resistor [24,25,29]. Impedance of the aforementioned equivalent circuit can be described through the equation below:…”