. 2019 Sep 20;19(19):4057. doi: 10.3390/s19194057

Table 3.

Comparison between fault identification methods [34,35,47].

Method	Description	Fault Identification and Normal Aging	Gas Used
Key Gas Method (KGM)	Uses individual gas concentrations to identify the fault	PD, arcing, overheated oil, overheated cellulose	CO, H $_{2}$ , C $_{2}$ H $_{2}$ , C $_{2}$ H $_{4}$
Doernenburg Ratio Method (DRM)	Uses four gas concentration ratios: $\frac{{CH}_{4}}{H_{2}}, \frac{C_{2} H_{2}}{C_{2} H_{4}}, \frac{C_{2} H_{2}}{{CH}_{4}}, \frac{C_{2} H_{6}}{C_{2} H_{2}}$	Thermal decomposition, PD, arcing	H $_{2}$ , C $_{2}$ H $_{2}$ , CH $_{4},$ C $_{2}$ H $_{6}$ , C $_{2}$ H $_{4}$
Rogers Ratio Method (RRM)	Uses three gas concentration ratios: $\frac{{CH}_{4}}{H_{2}}, \frac{C_{2} H_{2}}{C_{2} H_{4}}, \frac{C_{2} H_{4}}{C_{2} H_{6}}$	Normal aging, PD, arcing, low temperature fault, thermal fault <700 $^{\circ}$ C, thermal fault >700 $^{\circ}$ C	H $_{2}$ , C $_{2}$ H $_{2}$ , CH $_{4},$ C $_{2}$ H $_{6}$ , C $_{2}$ H $_{4}$
IEC Ratio Method (IRM)	Uses three gas concentration ratios: $\frac{{CH}_{4}}{H_{2}}, \frac{C_{2} H_{2}}{C_{2} H_{4}}, \frac{C_{2} H_{4}}{C_{2} H_{6}}$	PD, low energy discharge, high energy discharge, thermal faults <300 $^{\circ}$ C, between 300 and 700 $^{\circ}$ C, and >700 $^{\circ}$ C	H $_{2}$ , C $_{2}$ H $_{2}$ , CH $_{4},$ C $_{2}$ H $_{6}$ , C $_{2}$ H $_{4}$
Duval Triangle Method (DTM)	Uses three gases corresponding to the increasing energy content or temperature of the faults	PD, low energy discharge, high energy discharge, thermal faults <300 $^{\circ}$ C, between 300 and 700 $^{\circ}$ C, and >700 $^{\circ}$ C	C $_{2}$ H $_{2}$ , CH $_{4},$ C $_{2}$ H $_{4}$
Duval Pentagon Method (DPM)	Uses five gases corresponding to the increasing energy content or temperature of the faults	Normal aging, PD, low energy discharge, high energy discharge, thermal faults <300 $^{\circ}$ C, between 300 and 700 $^{\circ}$ C, and >700 $^{\circ}$ C	H $_{2}$ , C $_{2}$ H $_{2}$ , CH $_{4},$ C $_{2}$ H $_{6}$ , C $_{2}$ H $_{4}$