Search results for "Global Earthing Systems"
showing 6 items of 6 documents
Currents Distribution During a Fault in an MV Network: Methods and Measurements
2016
When a single line to ground fault happens on the MV side of a HV/MV system, only a small portion of the fault current is injected into the ground by the ground-grid of the faulty substation. In fact the fault current is distributed between grounding electrodes and MV cables sheaths. In systems with isolated neutral or with resonant earthing this may be sufficient to provide safety from electric shock. Experimental measurements were performed on a real MV distribution network: a real single line to ground fault was made and fault currents were measured in the faulty substation and in four neighboring substations. In this paper the problem of fault current distribution is introduced, the tes…
Current and Voltage Behaviour During a Fault in a HV/MV System: Methods and Measurements
2015
When a single line to ground fault happens on the MV side of a HV/MV system, only a small portion of the fault current is injected into the ground by the ground-grid of the faulty substation. In fact the fault current is distributed between grounding electrodes and MV cables sheaths. In systems with isolated neutral or with resonant earthing this may be sufficient to provide safety from electric shock. Experimental measurements were performed on a real MV distribution network: a real single line to ground fault was made and fault currents were measured in the faulty substation and in four neighbouring substations. In this paper the problem of fault current distribution is introduced, the te…
A Method to Evaluate Voltages to Earth During an Earth Fault in an HV Network in a System of Interconnected Earth Electrodes of MV/LV Substations
2008
An easy and swift method to evaluate, in a system of interconnected earth electrodes, earth potentials on earthing systems of medium-voltage/low-voltage (MV/LV) substations, in an event of single-line-to-earth fault inside a high-voltage/medium- voltage (HV/MV) station, is presented. The advantage of the method is the simplicity of the mathematical model for solving complex systems of any size with a sufficient accuracy for practical purposes. This paper shows the results of simulations, performed on networks with different extensions and characteristics, organized in easy-to-read graphs and tables. A comparison of these results with the values obtained according to the procedure explained …
Results of the research on global earthing systems: A contribution to the problem of their identification
2013
The paper presents a study on the factors that can have influence on the rise of a Global Earthing System. The first part of the work deals with: - the definition of proximity, interconnection and quasi-equipotential; - the influence of the presence of HV/MV stations on the dangerous voltages and on the permissible voltage limits; - the dependence of the hazardous condition for persons on the different kind of fault; - the effects on safety of the coexistence of HV, MV and LV systems. In the second part, starting from the discussion on the themes above-mentioned and on the results of the studies, measurement campaigns and simulations on interconnected earthing systems done in the last fifte…
On the hazardous situations due to the presence of HV/MV substations in urban areas
2017
The paper focuses on the hazardous situations that can rise in urban areas in case of earth fault inside a High Voltage/Medium Voltage station. IEEE and IEC/EN Standards and technical documents are examined and discussed, in order to propose some practical guidelines for a safe integration of such installations in contexts characterized by the presence of low voltage systems and not trained persons.
Risk indexes for studying interconnected earthing systems inside MV networks
2006
The paper presents a risk-evaluation-based approach to the issue of interconnection between the earth electrodes of the MV/LV substations within MV networks. After a short introduction on the interconnection between earthing systems, the paper proposes four risk indexes defined starting from the safety requirements given by CENELEC HD 63 7 S1. The indexes allow one to put in evidence, in a clear way, the benefits of the interconnection in terms of reduction of risk of critical electric shock for persons and of stress on the insulation of the LV devices in the presence of single line to earth faults and double earth faults inside MV/LV substations and single line to earth faults inside HV/MV…