An inter-turn short circuit (ITSC) in a power transformer winding is a primary cause of transformer failure. Existing methods for ITSC identification have limitations when applied in field conditions. To address this issue, a mobile hardware–software system for identifying electrical equipment parameters (PAK IP-10) has been developed, based on analyzing the decay of a direct current pulse. Verification of the test results for reproducibility, using Cochran’s criterion, demonstrated that the developed PAK IP-10 can be recommended for identifying the presence or absence of inter-turn short circuits in transformer windings.

Keywords: power transformer, inter-turn short circuit, identification, direct current decay test, Cochran’s criterion

One of the causes of local overheating of submersible electric motor caused by the presence of a significant variation of electromagnetic parameters of rotor packages (RP) in the assembly of submersible electric motor is investigated in this paper. Due to the presence in the assembly of RPs with an active resistance much lower than the average resistance of the assembly, the electrical losses in RPs with resistance higher than the average increase, respectively, their heat generation increases. With the help of statistical analysis methods, the distribution of electromagnetic parameters as a two-dimensional random variable was investigated, the "convolution" of the two-dimensional distribution law was constructed. The analysis of the "convolution" of the two-dimensional law of distribution of electromagnetic parameters of the RP showed that there is a high probability of a significant scatter of parameters of the RP in the assembly.

Keywords: submersible electrical motor, rotor package, statistical analysis, local overheating, interrepair period