Evaluation of parasitic resistance in voltage-driven electrical resistance tomography

Electrical resistance tomography (ERT) is an effective method for monitoring electrical conductivity distribution in the field using boundary measurement information. In applications with a large pipe diameter and large load variation, voltage-driven ERT (ERTv) can overcome the limitations of current-driven ERT (ERTc). A voltage source is used in ERTv to apply an excitation signal to the electrode, and can provide a large output signal. Meanwhile, saturation will not occur when the load of the field shows large fluctuations. However, the main disadvantage of an ERTv system is that the parasitic resistance in the system has an influence on the measurement results which cannot be ignored. The existence of parasitic resistance can cause measurement errors and reduce the reliability of ERTv systems. In this paper, the influence of parasitic resistance was evaluated and the trend of variation of this effect with different background conductivities was studied. The index k(r) was defined to find the relationship between parasitic resistance and background conductivity. When k(r) <= 3 x 10(-2), the reconstructed image can better reflect the actual conductivity distribution. At the same time, the applicable background conductivity range of the system can be acquired according to k(r), when the value of parasitic resistance in the system is known in advance.