# Risk Assessment Algorithm for Power Transformer Fleets Based on Condition and Strategic Importance
## 3 Case Study, Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Manufacturer**} & \multirow{2}{*}{\
\begin{tabular}{c} **Type/** \\ **Application** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Load** \\ **Factor** \\ \end{tabular} } & \multirow{2}{*}{**Voltage**} & \multirow{2}{*}{**N-1** \\ **Criterion** \\ \end{tabular} } & \multirow{2}{*}{**Location**} & \multirow{2}{*}{**Critical**} & \multirow{2}{*}{**Raved**} & \multirow{2}{*}{**Mean**} & \multirow{2}{*}{**Security**} & \multirow{2}{*}{**Unavailability**} \\  & & & & & & & **(OVA)** & **(MAVA)** & & **Level** \\ \hline Known & In-service & 0.922 & 132/33 & Yes & Urban & Several & 85 & 59 & 16\&4 & 20 to 30 times \\ Well-Known & In-service & 0.283 & 132/33 & Yes & Urban & Several & 85 & 73 & 2\&3 & 20 to 30 times \\ Well-Known & In-service & 0.828 & 132/132 & Yes & Rural & Several & 20 & 16 & 1\&2 & 20 to 30 times \\ Well-Known & In-service & 0.539 & 500/220 & No & Rural & Several & 50 & 25 & 26\& 3 & 60 times \\ Unknown & In-service & 1.183 & 132/132 & Yes & Urban & A few & 70 & 63 & 2 & 20 to 30 times \\ Well-Known & In-service & 0.371 & 132/33 & Yes & Industrial & Several & 45 & 18 & 16\&4 & 20 to 30 times \\ Unknown & Standby & 0.000 & 500/220 & Yes & Urban & None & 55 & 39 & 1 & 60 times \\ Known & In-service & 0.585 & 220/132 & Yes & Rural & A few & 85 & 24 & 5 & 50 times \\ Known & In-service & 0.784 & 132/33 & No & Industrial & Several & 65 & 24 & 1\&2\&3\&4\&4 & 20 to 30 times \\ Well-Known & In-service & 0.361 & 132/33 & Yes & Rural & A few & 75 & 43 & 1\&2\&3 & 20 to 30 times \\ Known & Mobile & 0.269 & 132/132 & Yes & Urban & A few & 75 & 74 & 5 & 20 to 30 times \\ Known & In-service & 0.306 & 220/132 & N/A & Urban & None & 25 & 24 & 4 & 50 times \\ Well-Known & In-service & 0.657 & 500/220 & Yes & Industrial & A few & 100 & 87 & 4 & 60 times \\ Known & In-service & 0.268 & 132/132 & Yes & Industrial & Several & 85 & 32 & 36\&4 & 20 to 30 times \\ Known & In-service & 0.236 & 132/33 & Yes & Urban & None & 65 & 31 & 3 & 20 to 30 times \\ Known & In-service & 0.844 & 220/132 & Yes & Urban & Several & 75 & 19 & 3 & 50 times \\ Well-Known & In-service & 0.648 & 132/132 & N/A & Urban & Several & 100 & 84 & 3 & 20 to 30 times \\ Well-Known & In-service & 0.294 & 220/132 & Yes & Industrial & A few & 75 & 36 & 1\&2\&2\&3 & 50 times \\ Known & In-service & 0.350 & 220/132 & Yes & Rural & Several & 50 & 22 & 1\&2\&3\&3 & 50 times \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Transformers fleet operative features. values are greater than [PERSON]'s method; that can be explained by the low furan content and the good CO2/CO ratio of the PT. Meanwhile, for units 7 and 18 whose values are lower than [PERSON]'s, their respective CO2/CO ratios are 1.35 and 12.49. According to [4] CO2/CO ratios lower than 3 may be an indication of a fault in the insulating paper, while CO2/CO ratios higher than 10 may indicate accelerated thermal degradation at low temperature. The proposed method for the _DP_ includes these considerations in its algorithm, thus the differences with [PERSON]'s equation are justified. It also serves as an indicator of the importance of the CO2/CO relationship in determining the real state of the insulating paper. The proposed methodology ensures a more comprehensive estimate of the condition of the insulating paper. However, it was noted a certain degree of inelasticity in the results. This can be attributable to the nature of the trapezoidal fuzzy membership functions (TFMF), where they maintain the same value unless the input value moves to an interception zone between membership functions or another function at all. For the technical condition of the PT, those units 3, 17, 18 and 19 were the units with the most satisfactory HI results. Similarly, the units with the worst condition were PTs number 7, 8, 10 and 16. For the rest of the assessed fleet, the HI values vary from 0.35 to 0.8 indicating an intermediate condition. Furthermore, most of the transformers with high HI values present very low _DP_ estimations.