Transformer Oil Testing

SGS provides online transformer testing (OTT) to determine the basic electrical properties of transformer oil. From this you can identify if the oil is suitable for further use or whether necessary actions like filtration or regeneration are needed. Transformer oil is crucial in the cooling process of the transformer but it is subject to electrical and mechanical stress or possible chemical contamination during its lifecycle. Periodic testing provides an indicator of these issues as they arise. A fast reaction ensures enhanced component life and reduced oil costs, while maximizing safety and preventing untimely failures. The SGS OTT program is based on more than 20 years experience with innovations, such as LIMS software and a live web interface, continually being introduced. This program, combined with the recommended testing schedule, provides a complete solution to your transformer testing needs. All analyses are carried out to IEC, ASTM, ISO standards in NATA certified laboratories.

SGS Online Transformer Testing (OTT)

The SGS OTT testing program incorporates LIMS software to produce a multi-test report that includes all historical results. By including historical information it is possible to understand changes or increases in key gases and the rate of gas production. SGS expert transformer diagnostic technicians prepare your data and make the analysis reports available for trending and editing via a live web interface. This means you can access to your data at any time.

The OTT program, combined with our oil-sampling program, analysis services and extensive on-site maintenance services, gives you a complete package with which to monitor and maintain your electrical transformers.

The recommended testing schedule:

• OTT 1 (First Year) - Combine tests (DGA, Moisture, Acidity, Dielectric Breakdown, IFT) Furan, PCB, DDF, DBPC
• OTT 2 (Annually) - Combine tests (DGA, Moisture, Acidity, Dielectric Breakdown, IFT)
• OTT 3 (Subsequent years) - Combine tests (DGA, Moisture, Acidity, Dielectric Breakdown, IFT) Furan, PCB, DDF, DBPC

Specific diagnostic analyses include:

• Moisture Analysis (IEC 60814) – Moisture on oil can affect the electrical properties of the oil and accelerate the chemical deterioration of insulation paper
• Dielectric Breakdown (IEC 60156) – This measures the ability for oil to withstand electric stress
• Acidity (IEC 60296) – Used to determine if insulating oil should be reclaimed or replaced
• IFT (Interfacial Surface Tension ISO 6295) – This test indicates the degree of oxidation and deterioration of insulating oil thus affecting the oils ability to perform its cooling and insulating properties
• DDF (Dissipation Factor and Resistivity IEC 60247) – Measures the leakage current through oil to determine the deterioration and/or contamination of insulating
• DGA (Dissolved Gas Analysis IEC 60567 & IEC 60599) – Results of this analysis indicate the degree of cellulose insulation degradation and highlight initial faults that may be occurring in the transformer
• PCB Tests (ASTM D4059) – Carried out to detect the existence of Polychlorinated Biphenyls in transformers and capacitors
• Furan Analysis (IEC 61198) – When combined with dissolved gas analysis, this test determines the level of cellulose insulation degradation
• DBPC Analysis (ASTM D4768) – This test measures the anti-oxidant (2,6 Ditertiary-Butyl Para-Cresol) concentrations in insulating oil

Other additional Transformer Oil Testing available at SGS:

• Density – ASTM D4052
• Viscosity – ASTM D445
• Corrosive Sulphur Test – ASTM D1275B
• Oxidation – IEC 61125
• Sediment and sludge – AS 1883
• Flash point – ASTM D3828
• Pour point – ASTM D97
• Particle count – NAS 1638 & ISO 4406
• Wear metal analysis – ASTM D5185
• Degree of polymerization – ASTM D4243
• Oil sample collection
• Transformer oil filtration and regeneration

Contact your SGS representative for further information on scheduling your testing program.