Ohmic stray currents

Ohmic voltage drops of the protection current were exclusively involved in the processes for 7/ -free potential measurements described above. Besides this, other foreign currents can cause potential drops and falsify the potential measurement (e.g., cell currents, equalizing currents and stray currents). 

Ohmic interference the production of electrical potentials in conductors by electrical contact, by arcing or by a local voltage cone, caused by fault currents or stray currents in the soil (see Chapter 15). 

Still in the experimental phase of application in concrete [11]. Other measurements that can help in detecting the presence of stray current in reinforced concrete are based on the potential difference present between different parts of the structure, due to the ohmic drop produced by the stray current... 

L. Bertolini, P. Pedeferri, B. Bazzoni, L. Lazzari, Measurements of ohmic drop free potential in the presence of stray current , NACE International Corrosion 98 Conference, paper 98560, March 1998. 

Fig. 28. (a) Sketch of current lines of the dielectric displacement current between a contact needle and a counter-electrode indicating the influence of the stray capacitance, (b) Equivalent circuit (including the stray capacitance) representing microelectrode measurements on single crystals and the two simplified subcases for ohmic and non-ohmic microelectrodes. 

In all cases the ohmic drop is proportional to the current density. Special care should be given to transients at short times when large currents may flow, possible error sources being current oscillations, double layer charging and stray capacitance to ground. 

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