Tests for a Bare Structure

When current requirement tests are made on an all-bare structure, results are typically quite different Assume, as shown by the illustration in Fig. 13.33 that DC is forced to flow from a temporary ground connection to the system section being studied, and determining how much current will be needed to protect that section. 

The output of the current source shown in Fig. 13.33 may be adjusted until protective potentials are attained at the ends of the section to be protected. When working with bare surfaces, the current should be allowed to flow steadily, which will permit the surface to polarize to some degree depending on the duration of the test. Full polarization on a bare surface may take weeks to achieve. However, if the increase in protective potential during the test is plotted versus time at a fixed current output, the curve can be extended to give a rough approximation of the potentials that would be obtained with complete polarization. 

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