Determination of electrode spacings in laboratory tanks to obtain appropriate value of electric voltage

Purpose. The aim is to study the electrical potential distribution in dimensional limited and electrically insulated volume. Мethodology. It includes numerical simulation of stationary processes in Comsol 4.3а program using DC current’s module . Results. The numerical simulation was carried out for the area of electrically insulated tank. It length was L3 = 3[m] with depth of conducting medium H = 0.4[m]. The reference areas were L10 = 10[m] and L15 = 15[m] with the same depth as the regarded tank. The reference areas represents infinite medium with conductance about 200 [S]. The electrodes with potentials –10 [V] and +10[V] are placed on the top of tank. The primary problem was solved with stationary conditions and the parametrically changed values (parameters) were: length of laboratory’s tank (L), distance of electrodes (d) and depth of conducting medium (H). To evaluate the influence of the non conducting walls on results of measurements were used the results of potential for the area with length L10, L15 representing an infinite medium. Thus was calculated the percentage error of measurements due to medium limited by non conducting walls. Conclusions.
The minimum influence of non conducting walls on electric voltage, not exceeding 1 %,  is experienced for electrodes with spacing up to  1/6 of the length of tank. Originality. Apart from potential distribution being presented, an estimation of distance of feeding electrodes on resulting voltage values of measurements in limited area referenced to unlimited area are also given. Practical significance. The results obtained is of high significance because it to be used for physical modelling of   2-D and 3-D electrical imaging surveys (electroresistive tomography) methods.