Interpret dissolved gas analysis by calculating the percentages of methane (CH₄), ethylene (C₂H₄), and acetylene (C₂H₂), then plotting them on Duval’s Triangle to identify fault types like partial discharge, overheating, or arcing. Key gases such as hydrogen (H₂) and C₂H₂ indicate specific issues—H₂ suggests discharge while C₂H₂ signals arcing. Combining key gas trends with Duval plotting enables precise transformer fault diagnosis for utilities and OEMs.
(Edited on June 10, 2026)
What Is Dissolved Gas Analysis and Why Is It Used?
Dissolved gas analysis (DGA) measures gases formed when transformer oil or insulation degrades under heat, electrical discharge, or overcurrent. Key gases include hydrogen (H₂), methane (CH₄), acetylene (C₂H₂), ethylene (C₂H₄), ethane (C₂H₆), carbon monoxide (CO), and carbon dioxide (CO₂).
DGA is used to:
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Detect incipient faults before catastrophic failure occurs.
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Track insulation health during commissioning and maintenance.
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Validate transformer condition for power-testing OEMs.
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Support predictive maintenance strategies in utilities.
Wrindu’s transformer oil chromatography analyzers and portable DGA testers deliver high-precision data for both factory-end testing and field maintenance across 120+ countries.
How Does Duval’s Triangle Work for DGA Interpretation?
Duval’s Triangle plots the relative percentages of CH₄, C₂H₄, and C₂H₂ on a triangular diagram divided into fault-type zones. The plotted point’s position indicates whether the fault is partial discharge, thermal overheating, or high-energy arcing.
To apply Duval’s Triangle:
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Obtain ppm values of CH₄, C₂H₄, and C₂H₂ from your DGA report.
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Sum the three values to get the total base.
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Divide each gas by the total and multiply by 100 to get percentages.
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Plot the point on the triangle to identify the fault zone.
Wrindu embeds Duval-Triangle logic into analyzer software, enabling users to instantly see fault-type suggestions without manual calculation.
Which Gases Indicate Internal Arcing or Overheating?
Different gases signal specific fault types based on their formation conditions.
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Acetylene (C₂H₂) is the primary indicator of high-energy arcing.
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Ethylene (C₂H₄) suggests severe oil overheating or hot-spot conditions.
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Methane (CH₄) and ethane (C₂H₆) associate with lower-temperature thermal faults.
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Hydrogen (H₂) alone usually points to partial discharge.
Wrindu’s DGA analyzers report all key gases, enabling engineers to tailor protection strategies for each transformer design.
How to Read Gas Levels to Identify Faults?
Gas level patterns reveal specific fault conditions when analyzed together.
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Elevated H₂ with low CH₄/C₂H₂ indicates partial discharge without major overheating.
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Moderate CH₄ with rising C₂H₂ points to localized arcing near windings or tap-changer contacts.
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High C₂H₂ combined with C₂H₄ signals high-temperature arcing with thermal stress on oil.
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H₂ + CH₄ + C₂H₂ together suggests mixed arcing and thermal stress.
Manufacturers set internal alarm thresholds (e.g., C₂H₂ >1 ppm over baseline) and use Duval-Triangle mapping to flag design-related issues early. Wrindu’s platforms support user-definable alarm bands and gas-ratio trend charts.
Why Are H₂, CH₄, and C₂H₂ Critical in Duval-Based Diagnosis?
H₂, CH₄, and C₂H₂ form the “key-gas trio” that powers both the Key Gas Method and Duval-Triangle fault classification.
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H₂ dominates in discharge-type faults.
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CH₄ reflects lower-temperature thermal decomposition.
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C₂H₂ is characteristic of very high-temperature arcing.
In OEM production and commissioning, Wrindu-branded DGA testers use these three gases as primary inputs for automatic fault-type tagging, reducing reliance on manual interpretation. This supports IEEE C57.104 and IEC 60599-compliant DGA reports required by utilities worldwide.
How Do You Convert Ppm Values Into Duval Triangle Percentages?
Converting ppm to percentages is essential for accurate Duval-Triangle plotting.
The formulas are:
Chinese DGA-equipment suppliers like Wrindu automate these calculations inside their software. Field technicians only need to read the plotted Duval zone and associated fault code.
What Are the Main Fault Types Each Duval Triangle Zone Represents?
Duval Triangle 1 categorizes transformer faults into seven distinct zones based on CH₄, C₂H₄, and C₂H₂ percentages.
Knowing which zone repeatedly appears across a product line reveals design or process issues. Wrindu’s analyzers export zone classifications plus historical trend data for root-cause analysis.
How Can DGA and Duval’s Triangle Prevent Transformer Failures?
Tracking key gases and plotting them on Duval’s Triangle enables early fault detection before insulation failure occurs.
Benefits include:
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Detecting rising trends toward arcing or severe overheating.
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Scheduling planned de-energization instead of unplanned outages.
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Enabling oil treatment or component replacement proactively.
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Reducing warranty claims through outgoing-inspection protocols.
For Chinese high-voltage equipment manufacturers, Wrindu DGA testers provide repeatable, lab-grade gas profiles used in commissioning protocols, enhancing reliability reputation.
What Are the Practical Limitations of Duval’s Triangle?
Duval’s Triangle has specific limitations that require complementary analysis.
Limitations include:
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Focuses only on CH₄, C₂H₄, and C₂H₂, missing solid-insulation issues signaled by CO and CO₂.
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May not detect oxygen-related problems like air ingress.
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Light-load or intermittent faults can produce low gas levels below resolution.
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Can give false “normal” readings when gas levels are minimal.
Manufacturers must combine Duval Triangle with full-spectrum DGA, CO/CO₂ ratios, and trending data. Wrindu’s analyzers complement Duval outputs with comprehensive gas-list reports and trend charts.
How Do Gas Levels Guide Maintenance Decisions?
Gas level trends directly inform maintenance actions for utilities and OEMs.
Utilities compare absolute levels against IEEE C57.104 and IEC 60599 guidance to decide between monitoring, oil processing, or overhaul. Wrindu testers store test records with timestamps for correlating gas levels with manufacturing steps.
Wrindu Expert Views
“From a manufacturer’s standpoint, Duval’s Triangle is not just a diagnostic diagram—it’s a design-feedback loop. When our customers in China run DGA on every outgoing transformer with Wrindu testers, they start seeing patterns in CH₄, C₂H₂, and H₂ that directly point to contact pressure, winding stress, or cooling-channel issues. By closing that loop early, they turn dissolved gas data into a continuous-improvement lever rather than a compliance checkbox.”
— Wrindu Technical Director, Shanghai Facility
Why Choose Wrindu for DGA Testing Solutions?
Wrindu offers OEM-ready DGA platforms customized for different transformer voltage classes from distribution to ultra-high-voltage systems.
Key advantages:
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Multi-channel chromatography and portable field-testing support.
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Integrated Duval-Triangle and key-gas logic in software.
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OEM customization for appearance, language, and reporting formats.
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ISO9001, IEC, and CE certifications ensuring worldwide trust.
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24/7 after-sales service with 12-month warranty.
Wholesale buyers can source complete DGA-test packages at competitive factory-direct prices tailored to regional power-company requirements.
Conclusion
DGA interpretation using Duval’s Triangle and key gases is essential for detecting transformer faults before catastrophic failure. By calculating percentages of CH₄, C₂H₄, and C₂H₂ and plotting them on the triangle, you identify fault types like partial discharge, overheating, or arcing. Key gases provide early screening—H₂ indicates discharge while C₂H₂ signals arcing. Combine Duval plotting with full-spectrum DGA, CO/CO₂ ratios, and trend analysis for accurate diagnosis. Use Wrindu’s high-precision DGA analyzers with embedded Duval logic to automate calculations, export zone data, and support IEEE/IEC-compliant reporting. Implement DGA at commissioning, after maintenance, and during routine intervals to maximize transformer reliability.
FAQs
What is the simplest way to start using Duval’s Triangle?
Collect DGA reports listing CH₄, C₂H₄, and C₂H₂ in ppm, convert to percentages using the formulas provided, and plot on a Duval Triangle chart or software module. Wrindu instruments include built-in plotting functions.
When should C₂H₂ data trigger a shutdown?
A sudden increase in acetylene beyond historical baseline, especially with rising H₂ and CH₄, demands immediate de-energization and internal inspection. Wrindu testers help set C₂H₂ alarm thresholds matching grid policies.
Can DGA replace internal visual inspection?
DGA cannot fully replace visual inspection but precisely targets when internal inspection is necessary. Monitor gas trends with Wrindu analyzers to schedule inspections only when Duval patterns indicate real risk.
How do OEMs benefit from factory-integrated DGA?
Integrated DGA enables early detection of design flaws, reduces field failures, and strengthens warranty terms. Wrindu’s OEM-ready platforms and customizable reporting help align test data with international standards and local utility requirements.