Dissolved gas analyzer (DGA)

Data records

• A dissolved gas analyzer extracts the gases dissolved in a transformer's insulating oil and measures the concentration of each, because the gases formed by overheating, arcing and partial discharge in the oil and paper dissolve in the oil and reveal a developing fault before it escalates. Source: GE Vernova product page, web page edition. Verified 2026-10-27. Record instr.dissolved-gas-analyzer.definition
• The gases measured are hydrogen, methane, ethane, ethylene, acetylene, carbon monoxide and carbon dioxide, with oxygen and nitrogen added by some analyzers, and moisture in oil is often reported alongside them. Source: Doble article page, web page edition. Verified 2026-10-27. Record instr.dissolved-gas-analyzer.fault-gases
• The gas concentrations are interpreted with key-gas, gas-ratio and triangle methods that associate the pattern of hydrogen, hydrocarbon gases and carbon oxides with thermal faults, electrical discharges and degradation of the cellulose insulation. Source: Doble product page, web page edition. Verified 2026-10-27. Record instr.dissolved-gas-analyzer.fault-interpretation
• A gas chromatograph separates the extracted gas mixture in a column and measures each component as it elutes; it consumes a carrier gas, carried on a portable unit in a refillable module, and portable chromatographs analyze syringe samples in the field. Source: Doble product page, web page edition. Verified 2026-10-27. Record instr.dissolved-gas-analyzer.gas-chromatography
• An online monitor separates the dissolved gases from the oil through a semipermeable membrane that comes to equilibrium with the oil, so that oil and oil vapor never enter the gas measurement system. Source: Doble article page, web page edition. Verified 2026-10-27. Record instr.dissolved-gas-analyzer.gas-extraction
• An online monitor repeats its measurement at a set interval, as often as hourly, and raises its sampling rate automatically when a gas concentration passes a caution or alarm setting, so a developing fault is followed more closely than periodic laboratory analysis of drawn samples allows. Source: GE Vernova product page, web page edition. Verified 2026-10-27. Record instr.dissolved-gas-analyzer.online-vs-laboratory
• Photoacoustic and infrared analyzers measure the hydrocarbon gases and carbon oxides by their absorption of infrared light and consume no gas, while hydrogen is measured by a thermal conductivity sensor; some of these monitors calibrate themselves in service against water vapor from a small reservoir. Source: Doble article page, web page edition. Verified 2026-10-27. Record instr.dissolved-gas-analyzer.photoacoustic-infrared
• A portable analyzer takes the oil sample in a syringe, extracts the dissolved gas into a headspace of extraction gas by shaking, and measures the gas on a built-in micro gas chromatograph on site; a laboratory kit adds a syringe shaker for higher sample throughput. Source: Doble product page, web page edition. Verified 2026-10-27. Record instr.dissolved-gas-analyzer.portable-field
• A single-gas monitor senses hydrogen together with moisture directly in the oil, without pumps or membranes, and gives a continuous trend reading in place of occasional sampling, as an early warning of a fault before it escalates. Source: Vaisala product page, web page edition. Verified 2026-10-27. Record instr.dissolved-gas-analyzer.single-gas-monitor
• The instrument class is written Dissolved gas analyzer (DGA). Value: Dissolved gas analyzer (DGA). Source: Electrical Testing Reference editorial taxonomy, 2026-10 edition. Verified 2026-10-27. Record instr.dissolved-gas-analyzer.title