Partial Discharge Phenomena in Gas-Insulated Systems

Partial discharges are localised electrical discharges that occur within gas-insulated systems when the electric field strength surpasses the breakdown threshold of minute voids, surface imperfections or contaminant inclusions. These discharges do not bridge the main electrodes but generate stress concentrations that erode insulation over time, leading to eventual failure. Gas-insulated systems, typically employing sulphur hexafluoride (SF6) as the insulating medium, are valued for their compactness and high dielectric strength. However, the chemical by-products of partial discharge—detectable as SF6 decomposition components—represent both a diagnostic opportunity and an environmental concern. Contemporary research addresses the interplay between discharge inception mechanisms, induced chemical reactions and their by-product signatures, while seeking robust detection methods that marry electrical, acoustic, optical and chemical analyses. Advances in understanding the influence of operating pressure, waveform polarity, impurity levels and electrode geometry have underpinned novel condition-monitoring approaches that promise to enhance the safety, reliability and sustainability of high-voltage gas-insulated infrastructures.

Research from Nature Portfolio

In a seminal study, researchers developed a probabilistic framework to correlate SF6 decomposition patterns with specific types of partial discharge faults. By integrating an Arrhenius-based reaction model with six distinct machine-learning algorithms, the study demonstrated accurate identification of coexisting discharge fault types within gas-insulated switchgear. Concentrations and ratios of key decomposition species—such as SO2, SOF2, SO2F2, CF4 and CO2—were used as input features, yielding diagnostic models capable of predicting both fault severity and underlying defect mechanisms. This interdisciplinary approach has laid the groundwork for data-driven evaluation and optimisation of GIS condition assessment.

Partial Discharge Phenomena in Gas-Insulated Systems publication trend

The graph below shows the total number of articles in partial discharge phenomena in gas-insulated systems across all publications each year (not limited to Nature Index journals).

Technical terms

Partial discharge: A localised electrical discharge in a gaseous or solid dielectric that does not completely bridge adjacent conductors, often occurring at voids or defects.

Gas-insulated system (GIS/GIL): A high-voltage apparatus in which insulation and dielectric strength are provided by pressurised insulating gas, typically SF6, surrounding the conductors.

Sulphur hexafluoride (SF6): A heavy gas with exceptional dielectric properties used in medium- and high-voltage electrical equipment; decomposition under discharge yields diagnostic by-products.

Decomposed component analysis (DCA): A diagnostic method that identifies and quantifies chemical species generated by the breakdown of SF6 under partial discharge conditions.

Axial diffusion: The longitudinal spread of gaseous by-products along the length of gas-insulated lines, governed by Fick’s law and affecting concentration measurements over distance.

References

1. SF6 Decomposed Component Analysis for Partial Discharge Diagnosis in GIS: A Review. IEEE Access (2022).
2. Effects of SF6 decomposition components and concentrations on the discharge faults and insulation defects in GIS equipment. Scientific Reports (2020).
3. Comprehensive Evaluation and Application of GIS Insulation Condition Part 1: Selection and Optimization of Insulation Condition Comprehensive Evaluation Index Based on Multi-Source Information Fusion. IEEE Access (2019).
4. Methods for alleviation of impacts of axial diffusion on decomposition products monitoring in gas‐insulated transmission lines. High Voltage (2021).