## 3 Results and Discussion
### Case Study C: Effect of EEC on Electrodes  
An EEC is deployed in regions with high soil resistivity to enclose electrodes to reduce tower footing resistance (TFR). This is normally indicated in case of a high soil resistivity (SR) value measured at the site, typically above 500 \(\Omega\cdot\)m in the case of a 500 kV tower. The use of EEC was incorporated in Design C, where it was considered as the better solution by TNB. The TFR value was found to be reduced by Design C and was further improved when the EEC was applied. Results of the use of this earthing design with the EEC are summarized in Table 6. They indicated that the TFR of the Tower T42 was reduced from 8.8 \(\Omega\) to 7 \(\Omega\), whilst for Tower T48, the TFR decreased from 9.2 \(\Omega\) to 7.7 \(\Omega\) and from 5.6 \(\Omega\) to 4.6 \(\Omega\) for Tower T50. Therefore, EEC was found to be very effective at reducing the earth resistance to less than 5 \(\Omega\), as per TNB requirement for the 500 kV lines in Malaysia.  
Similarly, a decreasing trend of TFR after the addition of EEC is shown in Figure 12, which clearly indicates an improvement made by the EEC deployment.  
Table 7 shows the percentage of TFR reduction after the addition of EEC to T42, T48 and T50 using the Design C. It can be seen that the EEC provided a promising solution, particularly for the towers located in a rocky area, where low soil resistivity and TFR are hard to achieve. Reductions of 20.45% for T42, 16.3% for T48 and 17.86% for T50 were obtained from this simulation.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Tower**} & \multicolumn{2}{c}{**Design C**} \\ \cline{2-3}  & **Tower Footing Resistance Value, \(\Omega\)** \\ \cline{2-3}  & **Without EEC** & **With EEC** \\ \hline T42 & 8.8 & 7 \\ T48 & 9.2 & 7.7 \\ T50 & 5.6 & 4.6 \\ \hline \hline \end{tabular}
\end{table}
Table 6: TFR analysis of Design C encased with EEC.  
Figure 12: Comparison of the TFR value with and without EEC implementation for Design C.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Earthing Design**} & \multicolumn{3}{c}{**Tower Footing Resistance Value, \(\Omega\)**} \\ \cline{2-3}  & **Tower T42** & **Tower T48** & **Tower T50** \\ \hline Design A & 26.3 & 20 & 15.2 \\ Design B & 25.3 & 20.3 & 13.9 \\ Design C & 8.8 & 9.2 & 5.6 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Tower footing resistance analysis of different design arrangements.  
It is interesting to note that the results obtained in this work are crucial for the next step of the line performance study. In the context of the criticality of this 500 kV line, which is known as very critical and a backbone of the transmission network in Peninsular Malaysia, this work was able to quantify the significance of each approach considered by the power utility via several earthing designs. Despite the fact that the solutions are unique to each utility, especially in the Southeast Asia (SEA) region, this work can be shared within the interested community of power utilities. Although the TFR generally decreases when EEC is applied to a selected design, the reduction may not be substantial [46]. This is particularly true in the case of these 500 kV lines, located in a high-terrain area with a rocky soil. It can be observed that the TFR is heavily dependent on weather conditions, such as the amount of rainfall, soil moisture and temperature of the surroundings, which is applicable for a country such as Malaysia [47]. When the temperature is too high, it leads to dryness of the soil, thereby affecting the soil resistivity value. Thus, it can be inferred that EEC is able to reduce the TFR, thus improving the overall transmission line performance.