Q222 : Using Multiple GPR Energizations on the Same Structure
Question Is it possible to use several GPR energizations on the same connected structure?
Answer It is possible to use two GPR energizations on the same connected structure, but you should be careful when doing so. The problem is apparent at low frequencies. A connected structure tends to be an equipotential at low frequencies. Specifying that two or more points on the structure are at different potential would be unphysical, and cause very large currents to flow in the network. In this sense, it is usually better to use no more than one GPR energization per structure.
The exception is when all GPR energizations have the same value (or nearly the same value). At worst, this is redundant and should have no effect, but it can be put to positive use, especially in large systems. A GPR energization of 0 Volt can be used, for instance, to connect a long structure to a perfect ground at regular intervals.
Another case for which several GPR energizations on the same structure could be justified is when lumped impedances are present in the structure. In this case, the impedances could reduce the magnitude of the current flowing in the structure to reasonable levels, and yield physical results.