This article focuses on improving techniques for detecting internal defects in the high voltage oil-filled coupling capacitor (HVOFCC). The purpose of the article is to improve the results of technical diagnostics of HVOFCC to control its technical condition based on analyzes of samples of mineral condenser oil (MCO) from this HVOFCC. The following methods were used: gas chromatography (GCh) in determining the concentrations of the components Н2, CН4, С2Н4, С2Н6, С2Н2, СО, СО2, Н2О in the volume of the operational MCO; determining the dependence solubility of air and H2 in MCO on temperature; diagnosing HVOFCC using the Rogers method; descriptions when clarifying the mechanisms of processes occurring in HVOFCC based on the results of diagnosis after its opening. The concentrations of components (Н2, CН4, С2Н4, С2Н6, С2Н2, СО, СО2, Н2О) in MCO samples from HVOFCC type CMP166/√3-0.014 were determined. The dependences of the solubility of air and H2 in MCO on temperature (in the temperature range of 255...373 K), as well as the solubility of gases Н2, CН4, С2Н4, С2Н6, С2Н2, СО, СО2 in this MCO at a temperature of 20 °C were found using the GCh method. Calculated concentrations of gases Н2, CН4, С2Н4, С2Н6, С2Н2, СО, СО2 in the air above the MCO surface in a sealed HVOFCC with internal defects. The Rogers method was used to diagnose HVOFCC based on the results of analysis of MCO samples by the GCh method. It is shown that the emergence and development of the internal defect “Flashover without Power Follow Through” in HVOFCC is facilitated by defects that have arisen during its manufacture and operation, namely, degradation of the MCO; destruction of the membrane boxes of the expander, penetration of MCO into it, penetration of air from the expander into the volume of MCO; the emergence and accumulation of combustible fire hazardous gases Н2, CН4, С2Н4, С2Н6, С2Н2, СО in the air volume above the MCO surface. The results obtained make it possible to increase the reliability of the results of diagnosing the technical condition of HVOFCC with cellulose solid electrical insulation based on the results of GCh analyzes of MCO samples during life tests or before repair. When conducting further research (after opening the HVOFCC during life tests or before its repair), MCO should be sampled to determine its physicochemical, thermophysical and electrophysical properties and the contents of diagnostic components in it (Н2; CН4; С2Н4; С2Н6; С2Н2; СО; СО2; H2S; Н2О; antioxidant additives; furan compounds).

The article presents the results of improving the methods for diagnosing the energy oil “Tp-30” of the pumping unit of the NPP equipment coolant circulation system. When studying the physicochemical and thermophysical properties of this oil, it was found that: the indicators “acid number”, “water content”, “content of mechanical impurities”, “content of the additive “Ionol”, “flash point”, “kinematic viscosity” correspond to the established standards. When determining the concentration of the additive “Ionol” in the sample of this oil: the method of adding the additive “Ionol” is used; in the obtained calculation formula, the values of the distribution coefficient for the additive “Ionol” in the system “turbine oil – additive “Ionol” – liquid extractant” are not used, which simplifies the study of the content of this additive in turbine oil. The water content in mineral turbine oil, determined by gas chromatography and coulometric titration with K. Fischer’s reagent, exceeds the water content in this oil, determined by thermal extraction. When studying the effect of liquid extraction temperature on additives “Ionol” (when determining its content in a given oil), it was found by gas chromatography that: the dependence of the distribution coefficients Ki on temperature t in the temperature range 15–75 0С can be expressed by the equation lnKi = А/(t+273) – B ; It is recommended to extract the Ionol additive from this oil at a temperature of (20 ± 2) °С or at a temperature of (65 ± 10) °С. When studying the effect of the chemical nature of the extractant on the ability to extract the “Ionol” additive from this oil, it was found that: ethanol, isopropanol, acetonitrile can be used as extractants of the “Ionol” additive, and the mixture “acetonitrile – water” cannot be recommended as such extractant. The results obtained can be used to improve the method of diagnosing mineral turbine oil “Tp-30” of the pumping unit of the coolant circulation system of the equipment of the second circuit of NPP with a pressurized water power reactor.