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Evaluation of the Ground Operating current in Industrial Systems with Network Distribution through MV cables Jorge Cardenas GE Digital Energy Email: [email protected] Introduction Oil and Gas Industrial installations have facilities that involve extent areas where the different loads are located several kilometres away from the generating points. In Oil and Gas Industry there is the particularity that the distribution of the energy is made through relatively long underground cables (Energy transmission is made through MV cables with lengths that goes in the range of 500 m. to 10 Km. approximately) and in the design frequently it is not taken in consideration the influence of the capacitive currents provided by the underground cables on the protective elements. This situation has a significant effect, mainly on the directional ground relays in MV, because the neutral frequently is grounded through a Zigzag transformer + a limiting resistor, that reduces the short circuit current, during ground faults, at levels similar that the ones produced by the capacitance of the MV cables. Results Direction of the Fault Currents during a Real Fault Phasor Analysis in Phase-to-Ground fault. . ANALYSIS Neutral Directional Element Performance in Generators Conclusions Phase-to-Ground Fault in a Typical Large Industrial Network Direction of Polarization and Fault Currents. ·Neutral direction element applied in Industrial Systems need to be analyzed with a network model detailed in all the main parameters as resistance, inductance and capacitance, in order to find the optimal forward and reverse covering areas. ·Neutral directional can be applied in Industrial Systems with relative long cables to optimize the protection not only on the feeders, also on the grounding transformer and Generators operating in parallel. Direction of the Fault Currents Current distribution during a phase-to-ground fault. Neutral Directional Element Performance ·Majority of Industrial Installations use high impedance grounding and as a consequence low phase-to-grounds currents in the range of the capacitance currents are usual during faults. This can produce a big change in the fault direction. As a consequence a detailed analysis is needed to determine the optimal setting of the directional element.