This work discusses the effect of proximity between the grounding cable and power cables of high hp 3-ph induction motor, on the operation of the unit of protection against earth fault current and on the system of cathodic protection of the pipes in deep wells, due to high circulating current of grounded cable, induced by the magnetic flux of a 3-ph current of induction motor because of the proximity effect.
The work contains practical beneficial experiments, in the work site, for measuring circulating currents, theoretical analysis, useful Conclusions and a very useful recommendation to the engineers deal with this field. It is shown that the reason of circulating current in the earthing cable and the cathodic protection cable is the neighboring of earthing cable to the power cables