This article considers one of the parts of the development of the input control device for film capacitors. Structural and functional schemes have been developed. The results of modeling the measuring circuit in the Microcap software package are presented. The results of the model experiment confirm the correctness of the calculations.

Keywords: input control, film capacitors, Arduino, Microcap, diagnostics

For the long-term operation of a power oil transformer, it is necessary to comply with all regulated checks of its technical condition, prescribed in the instructions. The current regulations provide for daily routine inspection and technical examination at least once a week. Famously, the heating of a power transformer during its operation is linked to the presence of active losses in the windings and core. High power transformers have impressive heat losses. Oil cooling systems are used to prevent that overheating of the transformer and damage to the insulation of the coil windings. The deterioration of the quality of the transformer oil causes an increase in active losses, due to which the efficiency of the power device decreases. This negatively affects the process of converting electrical en-ergy. The conclusion is that the quality of the oil directly affects the longevity of the power transformer. Thus, the most important functional elements from a control point of view are the transformer oil and the coil of the power device. Based on the foregoing, the urgent problem of technical control of electrical substations’ transformers is the development of methods and devices for express monitoring of the functional state of power oil transformers, which allow quick diagnostic information receiving, sufficient for a timely decision on the need for unscheduled repairs or maintenance.

Keywords: power transformer; transformer oil; impedance; diagnostics; functional state; dielectric loss tangent; equivalent circuit; MathCad