Several Common Methods For Detecting Transformer Oil Tanks

Transformer oil tank leakage detection is to ensure its sealing, to prevent leakage of insulating oil or gas infiltration of the important links, common leakage detection methods mainly include the following:

1.Visual inspection method

Method: through the naked eye or magnifying glass to observe the transformer shell, weld, flange connections, valves and other parts of the whether there are oil stains, traces of oil or wet phenomenon.

Applicable scenes: daily inspection or preliminary troubleshooting.

Advantages: simple and fast, no equipment.

Disadvantages: small leakage is difficult to find.

2.Soap Bubble Leakage Detection

Method: Apply soapy water to the suspected parts (e.g. weld seams, sealing surfaces) and observe whether bubbles are generated.

Applicable scenarios: localized small-scale leakage detection (such as valves, pipe interfaces).

Advantages: low cost, simple operation.

Disadvantages: Insensitive to small leaks or internal leaks.

3.Pressure decay method

Methods: Inflatable pressurization: fill the transformer oil chamber or gas relay with dry nitrogen or air (usually 0.03~0.05MPa), and monitor the rate of pressure drop after holding pressure.

Oil pressure test: pressurize the oil system and observe whether the pressure is stable.

Applicable scenarios: overall sealing test after installation or overhaul.

Advantages: quantitative detection, high sensitivity.

Disadvantages: need to stop the operation of the transformer, and need to keep pressure for a long time to observe.

4.Vacuum leakage detection method

Method: vacuum transformer (such as vacuum oil injection), monitor whether the vacuum continues to fall, to determine whether there is a leak.

5.Halogen Leak Detection Method

Method: Inject halogen-containing gas (such as Freon) into the transformer, and use halogen leak detector to detect the leakage site.

6.Infrared Thermal Imaging Leakage Detection

Methods: Infrared thermography to detect the surface temperature distribution of the transformer, the oil leakage site may be due to the difference in heat dissipation of the oil stains to show the temperature anomaly.

7.Gas tracer leakage detection (e.g. helium mass spectrometry leakage detection)

Methods: Fill helium into the transformer, use helium mass spectrometer to scan the outside and detect the location of helium escape. Or detect SF6 leakage in SF6 gas insulated transformers.

8.Dissolved gas analysis in oil (DGA) assisted leakage detection

Methods: By monitoring the abnormal elevation of hydrogen (H₂), methane (CH₄) and other gases in the transformer oil, to indirectly determine whether there is air or moisture infiltration.

9.Ultrasonic Leak Detection

Method: Use ultrasonic detector to capture high frequency acoustic signals generated by oil/gas flow at the leak.

10.Fluorescent Tracer Method

Method: Add fluorescent agent to the oil, irradiate the suspicious area with UV lamp, the leak will show fluorescence.

Selection basis

Tiny leaks: prioritize helium mass spectrometry, halogen leak detection or fluorescence method.

Rapid inspection: infrared thermography or ultrasonic method.

Power failure: pressure decay method or vacuum method.

Routine maintenance: visual inspection combined with soap bubble method.

Choose the appropriate method according to the type of transformer (oil-immersed, dry type, SF6 gas insulation), leakage medium (oil/gas) and detection needs (accuracy, cost, downtime). 

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