PHASE COORDINATE APPROACH TO CALCULATE EARTH-FAULT CURRENT AND SHOCK VOLTAGE

The paper summarises an alternative approach for the calculation of ea rth fault shock voltages for low voltage systems up to 1000 V without using the conventional symmetrical components. As the shock voltage at each section of the installation has to be modelled during fault cond itions, the system equations are formulated entirely in the phase co-o rdinates including the representation of neutral and grounding conduct ors. Test results on two different earthing systems demonstrate the ab ility in modelling the untransposed cable parameters and the influence of the unbalanced load currents on the postfault voltages. More accur ate results can thus be obtained as compared with other methods of cal culation.