Applicabilityĭo not use the Duval triangle to determine if a transformer has a fault, the triangle will always indicate a fault because there is no area allocated to ‘No fault’. The fault zone in which the point is located designates the likely fault type which produced that combination of gas concentrations. Concentrations (ppm) of methane (CH4), ethylene (C2H4), and acetylene (C2H2) are expressed as percentages of the total (CH4 + C2H4 + C2H2) and plotted as a point (%CH4, %C2H4, %C2H2) in a triangular coordinate system on a triangular chart which has been subdivided into fault zones.
