TOGAS Analysis System with manual sampling Nexis GC-2030TOGAS3 GC-2014TOGAS3

Significance of Topic

The analysis of dissolved gases and low-molecular-weight hydrocarbons in transformer oil (TOGAS) is critical for early fault detection and health monitoring of power transformers. Reliable quantification of these species helps in preventive maintenance, reduces downtime, and extends transformer service life.

Objectives and Study Overview

This application note presents a streamlined gas chromatography method combining manual sampling and timed valve switching for comprehensive TOGAS analysis. The approach separates permanent gases, light hydrocarbons, and carbon dioxide efficiently within a 16-minute cycle, demonstrating compliance with ASTM D3612C.

Methodology and Instrumentation

Method Workflow:

• Headspace sampling directs the gas phase from transformer oil into the GC inlet.
• Valve switching arranges flow paths: permanent gases and methane to Column 2 via Valve 2-1; heavier hydrocarbons and CO2 to Column 3 via Valve 6-5; CO2 is first converted to CH4 using a methanizer before FID detection.
• Detections: H2, CH4, CO by pulsed discharge helium ionization detector (PDHID); O2, N2 by thermal conductivity detector (TCD); CO2 (as CH4) and C2–C4 hydrocarbons by flame ionization detector (FID).
• Software control and data acquisition via LabSolutions GC workstation.

Used Instrumentation:

• Gas Chromatograph: Nexis GC-2030 TOGAS3 or GC-2014 TOGAS3
• Valves: Three timed switching valves
• Columns: Four packed columns (P-N, MS-13X, P-T, and methanizer bed)
• Detectors: PDHID, TCD, FID with in-line methanizer
• Optional: Headspace injector for automated sampling

Main Results and Discussion

– Total cycle time of 16 minutes achieves baseline separation of twelve analytes.
– Detection ranges cover trace concentrations (0.1‒1.0 ppm) up to bulk levels (50‒50 000 ppm) across H2, O2, N2, CH4, CO, CO2, C2H2, C2H4, C2H6, C3H6, C3H8, and i-C4H10.
– Chromatograms show sharp peaks for PDHID, TCD, and FID modules with minimal overlap, demonstrating effective valve timing and column selection.
– Methanizer conversion yields reliable quantification of CO2 at low ppm levels.

Benefits and Practical Applications

• High sensitivity and broad dynamic range for fault gas monitoring in transformer oil.
• Modular valve switching allows flexible method configuration and integration with headspace sampling.
• Rapid throughput supports routine QA/QC and on-site diagnostic testing.
• Compliance with ASTM D3612C ensures data comparability in industry settings.

Future Trends and Potential Applications

– Integration of automated sampling systems and real-time data analytics using machine learning for predictive maintenance.
– Development of portable GC-based TOGAS analyzers for field deployment.
– Advances in detector technology to improve detection limits and reduce analysis time.
– Expanded application to other oil-insulated apparatus and environmental monitoring.

Conclusion

The described TOGAS analysis method combines manual sampling, strategic valve switching, and multi-detector instrumentation to deliver fast, accurate, and comprehensive gas profiling in transformer oil. Its robustness and compliance with industry standards make it a valuable tool for transformer health assessment and preventive maintenance programs.