Background
Ethane in Power Transformers is a combustible gas that is produced within a power transformer and may provide an indication of incipient faults.
Chemical Structure
The following is the chemical structure of Ethane (C2H6)
Ethane is an organic chemical compound with two Carbon atoms bonded to 3 Hydrogen atoms each. It usually exists as a gas with the formula C2H6.
Formation
What causes the production of Ethane in transformer oil?
As the fault energy increases with higher oil temperatures the scission of the C-C bonds and their recombination into gases with a C-C single bond (607 kJ/mol), C=C double bond (720 kJ/mol) or C≡C triple bond (960 kJ/mol) occurs [1].
Fault Analysis
The IEEE guide for the interpretation of dissolved gases generated in oil-immersed transformers prescribes a limit of 65 ppm [3].
Ethane is usually a key gas associated with T1-type thermal faults with Methane (CH4) and minor amounts of Hydrogen (H2). For fault temperatures above 275 °C the Ethane production is found to exceed that of Methane [1].
Ethane can be used for fault diagnosis in the following ways:
- Ethane can be trended over a period of time to identify any increasing patterns.
- Rogers Ratios Method
- Doernenburg Ratio Method
- Duval’s Pentagon Method
- Ethane can be used in a health index as applied in the Transformer Age Index Model to assess the health of the transformer
References
| 1. | IEC60599, “Mineral oi-filled electrical equipment in service – Guidance on the interpretation of dissolved and free gases analysis,” 2007. |
| 2. | IEEEC57.104, “IEEE guide for the interpretation of gases generated in oil-immersed transformer,” IEEE Power Energy Society, 2019. |
| 3. | Cigre-Technical-Brochure-771, “Advances in DGA interpretation,” JWG D1/A2.47, 2019. |
[…] ratio method utilizes the ratios of the concentration of the key gases Hydrogen H2, Methane CH4, Ethane C2H6, Ethylene C2H4, and Acetylene C2H2. The following ratios are used CH4/H2, C2H2/CH4, C2H4/C2H6, and […]