Duvals Triangle Method

The Duval Triangle Method makes use of the three combustible gases CH₄, C₂H₄ and C₂H₂ that are transformed for representation in a triangular plot. The triangle is able to differentiate the fault types partial discharges, electrical faults (high and low energy arcing), and thermal faults (hot spots of various temperature ranges). Each point is derived from the percentage volume of the sum of the three gases. The triangle has a clockwise direction in terms of increasing percentage gas levels. Figure 1 presents the triangle with the definition of the six fault diagnosis regions [Duval1].

Figure 1: Duval’s Triangle [Duval1]

The Duval triangle is very useful in providing diagnoses when a fault condition is already identified due to fact that two of the three gases used (ethylene and acetylene) are products of high energy conditions. The conditions identified are partial discharges (PD), discharges of low energy (D1), discharges of high energy (D2), thermal faults of temperature < 300°C (T1), thermal faults of temperature 300°C < T < 700°C (T2), thermal faults of temperature > 700°C (T3).

One of the key challenges of this method is that there is no region in the triangle to indicate a normal ageing state for the transformer. Thus this method is not as effective in identifying a change from normal to defective state.

An updated version, the Duval triangle 4 is composed of the three gases H₂, CH₄ and C₂H₆ which is more specific for low energy or temperature (PD, T1 and T2) [Duval5]. The Duval Triangle 5 is composed of the gases CH₄, C₂H₄ and C₂H₆ which is formed more specifically for the identification of faults of high temperature to ascertain more information about thermal faults in paper and oil [Duval5]. 

Use the following link to the "Analysis" section to get the Duvals Triangle diagnosis of the oil samples. Enter the oil sample under "Sample 5" to get the diagnosis.

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