## 3 Electrode Station Configuration
### General Remarks  
To determine the electric field strength, in the area close to the electrode station, the superposition methodology is employed. In particular, in the configuration of straight frames parallelly positioned to the axis of the dam (Figure 4) and for each electrode positioned at (\(x_{\ell}\), \(y_{\ell}\)) coordinates of Figure 5, the theorem of superposition is employed via Equation (4) through Equation (9). Moreover, of particular consideration is the examination of current intensity densities, during periodic maintenance at the steady state, since it is then that the least favourable results are observed concerning safety distance and with regard to the point electric field criterion of 1.25 V/m. The whole array is adapted on an appropriate simulation canvas that, in the basic configuration, is 60 m (on the Ox semi-axis) by 160 m (on the yOy' axis--parallel to the frame), as in Figure 4, or even larger in case the configuration extends to a larger area. The step is 0.05 m by 0.05 m. The simulation involves the uniform loading of the station (be it 6-frame or 5-frame), by setting, in turn, the respective frames out of operation, thus determining the electric field strength all over the Oxy, as well as the area where it reaches values higher than \(E_{limit\_S}=1.25\) V/m. The results include the following, depending on the mode of operation:  
* The electric current density \(J_{st}\) with respect to the peripheral surface;
* The width of the electrode station critical zone \(d_{stv}\), perpendicular to the dam (on the xOx' axis);
* The length of the electrode station critical zone \(\ell_{cud}\) on the dam above the centre of the dam (on the yOy' axis);
* The length of the electrode station critical zone \(\ell_{cbl}\) on the dam below the centre of the dam (on the yOy' axis);
* The distance \(s_{bc}\) between the lowermost rod of the electrode station on the dam, which is connected to the power supply and the nearest point of protection (electrode not connected to power supply for maintenance purposes, dam end);
* The distance \(s_{uc}\) between the uppermost rod of the electrode station on the dam, which is connected to the power supply and the nearest point of protection (electrode not connected to the power supply for maintenance purposes, dam end);
* The distance of the lowermost rod of the electrode station \(\ell_{bc}\) on the dam from the centre of the dam that is connected to the power supply (on yOy');
* The distance of the uppermost rod of the electrode station \(\ell_{uc}\) on the dam from the centre of the dam, connected to the power supply (by yOy');
* The distance \(y_{pr}\) between the nearest point of protection (electrode not connected to power supply for maintenance purposes, dam end) from the centre of the dam that is connected to the power supply (on yOy');* The safety margin \(Dy_{pr}\) in relation to an initial preliminary study of a frame under the same conditions (where negative values indicate a requirement for a greater safety distance);
* The maximum electric field strength of the arrangement \(E_{max}\). To calculate the electrode-station-to-remote-earth resistance \(R_{el}\) and the maximum value of the absolute potential \(V_{rd\_max}\), the corresponding simulation is extended to a canvas of 150 km (Ox axis) by 160 m (yOy' axis--parallel to the dam axis) and with a step of 0.10 m up to 100 m, 1.0 m from 100 to 200 m, 5.0 m from 200 to 1000 m, 10 m from 1000 to 10,000 m, and 100 m from 10 km to 150 km on the Ox axis, and by 0.10 m on the yOy' axis, as in Figure 4. In case larger dimensions are required in the near-field, the respective canvas is suitably modified.