The Rogers Ratio Method is another ratio method very similar to the Dornenburg Method however it only utilizes the three ratios R1:CH₄/H₂, R2:C₂H₂/C₂H_4, R5:C₂H₄/C₂H₆. IEEE standard C57.104 has the following flowchart to explain the process [1].

Figure 2 below also taken from IEEE standard C57.104 provides a tabular list of the different conditions of the transformer based on the three ratios [1].

One of the challenges is that the Rogers Ratio provides an indication of the fault condition for a particular sample but not a trend. However, the fault types can be trended over time as displayed in Figure 3 below.

Use the following link to the “Analysis” section to get the Rogers Ratio diagnosis of the oil samples. Enter the oil sample under “Sample 5” to get the diagnosis.

Other dissolved gas analysis methods that may be of interest are:

• Duval’s Triangle 1
• Duval’s Triangle 4
• Duval’s Triangle 5
• LEDT
• Doernenburg’s Method
• Key Gas Method

References

1. IEEE C57.104, “IEEE Guide for the Interpretation of Gases Generated in Mineral Oil-Immersed Transformers,” IEEE Power and Energy Society