Rapid Dissolved Gas Analysis in Transformer Oils per ASTM D3612 Method on the Nexis GC-2030 Gas Chromatograph

Importance of the Topic

The analysis of dissolved gases in transformer oils is critical for assessing equipment health, detecting early fault conditions and preventing failures. DGA according to ASTM D3612 Method C enables reliable monitoring of transformer operation under growing electrical load demands and ensures extended service life.

Objectives and Study Overview

This work demonstrates a rapid dissolved gas analysis protocol using the Shimadzu GC-2030 Nexis gas chromatograph configured for ASTM D3612 Method C. It aims to optimize sample throughput, maintain analytical performance and expand the method to emerging transformer oil formulations.

Methodology and Instrumentation

Ultrahigh throughput headspace sampling was performed on an HS-20 autosampler using a 1 mL loop. The GC-2030 system implements two capillary columns and dual detectors. Key components include

• HS-20 headspace sampler with vial overlap function and 90-vial capacity
• Split/splitless inlet for constant linear velocity carrier flow
• 30 m Q-BOND column for hydrocarbon speciation
• 30 m molecular sieve PLOT column for permanent gases
• Thermal conductivity detector for H2, O2, N2
• Flame ionization detector with Jetanizer methanizer for CO, CO2 and hydrocarbons

Key Results and Discussion

Complete speciation of permanent gases and light hydrocarbons up to n-butane was achieved in just over 15 minutes. On the FID all analytes exhibited repeatability below two percent RSD and limits of detection below 2 ppm. The TCD showed a hydrogen LOD around 6.7 ppm and variable performance for oxygen due to low levels. Methanol spiked into the headspace was fully resolved at 12.66 minutes, demonstrating compatibility with FAME oil degradation products.

Benefits and Practical Applications

The streamlined system design reduces maintenance complexity and enables higher laboratory throughput. Fast run times and low detection limits support routine transformer health monitoring in QA QC and field service environments. The headspace platform facilitates rapid sample handling and method scalability.

Future Trends and Opportunities

Further enhancements may include larger headspace loops and advanced valve timing to improve sensitivity for low level permanent gases. With the adoption of bio derived transformer oils, the method can be extended to quantify light alcohols and alternative degradation markers, ensuring long term applicability.

Conclusion

The Shimadzu GC-2030 Nexis system meets ASTM D3612 Method C requirements, delivering rapid, reliable dissolved gas analysis with high sensitivity and simplified maintenance. This configuration offers a future proof solution for transformer diagnostics and evolving oil chemistries.

References

• ASTM D3612 Method C Standard Test Method for Analysis of Gases in Electrical Insulating Liquids by Gas Chromatography
• Shimadzu GC-2030 Nexis Gas Chromatograph Documentation, First Edition November 2021