## 3 Electrode Station Configuration
### General Remarks
Fourth Electrode Station Configuration--Straight Frames in Two Successive Rows, Each Parallel to the Longitudinal Axis and Non-Overlapping on the Vertical Axes of the Dam  
The respective configuration of the electrode station is performed according to Figure 8, where the straight frame has the characteristics of the basic configuration (\(N_{d\_frame}=13\), \(\ell_{p}=0.50\) m, \(\ell_{f}=6.00\) m). In the case of Korakia, the distance between the two rows of frames \(d_{fp}\) (on xOx\({}^{\prime}\)) is 11.0 m (against the estimated 10.90 m according to Table 10 in [2]); consequently, the total width, by Equation (31), will be 11.25 m, as is also the case in the third configuration. The estimated necessary distance between the frames \(s_{c}\) (on yOy\({}^{\prime}\)) is equal to 8.53 m (according to Table 10 in [2]), and applying Equation (33), the distance between two consecutive frames of the same row \(\ell_{Sfc}\) is determined as equal to max\(\{6\), 8.53\(\}\) = 8.53 and, due to length availability, is set as equal to 9.0 m. Therefore, the total necessary estimated length of the protective dam (behind which the arrangement will be placed), according to relation (34), will be equal to 66.0 m. Accordingly, for the case of Stachtoroi, the distance between the two rows of frames \(d_{fp}\) (on the xOx\({}^{\prime}\)) is 8.0 m (against the estimated 7.951 m, according to Table 11 in [2]); consequently, the total width, through Equation (31), will be 8.25 m, as is also the case in the third configuration. The estimated necessary distance between the frames \(s_{c}\) (on yOy\({}^{\prime}\)) is equal to 5.788 m (according to Table 11 in [2]), and applying Equation (33), the distance between two consecutive frames of the same row \(\ell_{Sfc}\) is determined as equal to max\(\{6\), 5.778\(\}\) = 6.0 and, due to length availability, is set equal to 6.0 m. Therefore, the total necessary estimated length of the protective dam (behind which the arrangement will be placed), according to Equation (34), will be equal to 47.6 m. From the respective simulation, the results of Table 3 are obtained, with the corresponding parameters of Table 2. Indicatively, Figure 24 shows the electric field strength and the area of developing electric field strength greater than 1.25 V/m for the most unfavourable case of the Korakia area, with five frames of operation (except for the non-operating fifth frame, under maintenance conditions). From the study of the results for the region of Korakia, the following emerges:  
* The deviation at the extremes of the array (along the yOy\({}^{\prime}\) axis) reaches up to 29.4 m, depending on the loading method, and along the xOx\({}^{\prime}\) axis, it reaches up to 49.0 m (especially when the five frames are loaded, except for the sixth or first). However, in the area of the non-operating frame, the electric field strength is 3.1 V/m (slightly above 2.5 V/m); therefore, no issues arise (regarding safety) when maintaining the frames, provided the diver has taken the appropriate measures. * The deviation in the maximum developing electric field strength of the electrode station compared to a single frame (26.14 V/m against 24.06 V/m, according to Table 10 in [2]) is of the order of 8.6%. That is, it is slightly higher compared to the first configuration (26.14 V/m against 26.09 V/m, according to Table 12 in [2]), almost identical compared to the third (26.14 V/m against 26.12 V/m according to Table 2), and much higher than that of the second (26.14 V/m against 19.26 V/m according to Table 1). * In Figure 24b, regions between the electrode frames are shown, where the electric field strength is significantly reduced below 1.25 V/m. However, this does not occur in the area of the frame that is set out of operation, although it does not exceed the value of 3.1 V/m.