Generation Characteristics of Solid Byproducts of the C4F7N-CO2-O2 Gas Mixture under PD Fault

Ran Zhuo; Mingli Fu; Dibo Wang; Yan Luo; Guoli Wang; Lei Jia

doi:10.1021/acsomega.3c00345

Generation Characteristics of Solid Byproducts of the C₄F₇N-CO₂-O₂ Gas Mixture under PD Fault

ACS Omega. 2023 Jun 20;8(26):23457-23464. doi: 10.1021/acsomega.3c00345. eCollection 2023 Jul 4.

Authors

Ran Zhuo^{1

2

3}, Mingli Fu^{1

2

3}, Dibo Wang^{1

2

3}, Yan Luo^{1

2

3}, Guoli Wang^{1

2

3}, Lei Jia^{1

2

3}

Affiliations

¹ Electric Power Research Institute, China Southern Power Grid, Guangzhou 510623, China.
² National Engineering Research Center of UHV Technology and New Electrical Equipment Fundamentals, Guangzhou 510623, China.
³ United Laboratory of Advanced Electrical Materials and Equipment Support Technology, China Southern Power Grid, Guangzhou 510623, China.

Abstract

With the gradual improvement of the requirements for the safe and stable operation of gas-insulated equipment (GIE), the eco-friendly insulating gas C₄F₇N-CO₂-O₂ has become the best choice to replace SF₆ and apply it to various medium-voltage (MV) and high-voltage (HV) GIE. At present, the generation characteristics of solid decomposition products of the C₄F₇N-CO₂-O₂ gas mixture under partial discharge (PD) fault need to be studied. In this paper, a 96 h PD decomposition test was carried out by simulating metal protrusion defects in GIE with needle-plate electrodes to study the generation characteristics of C₄F₇N-CO₂-O₂ gas mixture solid decomposition products under PD fault and their compatibility with metal conductors. It was found that obvious ring-shaped solid precipitates appeared in the central area of the surface of the plate electrode under the action of long-term PD, mainly including metal oxides (CuO), silicates (CuSiO₃), fluorides (CuF, CF_X), carbon oxides (CO, CO₂), and nitrogen oxides (NO, NO₂). The addition of 4% O₂ has little effect on the element composition and valence state of PD solid precipitates, but it can reduce their yield to a certain extent. The corrosion effect of O₂ in the gas mixture on metal conductors is weaker than that of C₄F₇N.