Phase co-ordinate approach to calculate earth-fault current and shock voltage

The paper summarises an alternative approach for the calculation of earth fault currents and shock voltages for low voltage systems up to lOOOV without using the conventional symmetrical components. As the shock voltage at each section of the installation has to be modelled during fault conditions, the system equations are formulated entirely in the phase co-ordinates including the representation of neutral and grounding conductors. Test results on two different earthing systems demonstrate the ability in modelling the untransposed cable parameters and the influence of the unbalanced load currents on the postfault voltages. More accurate results can thus be obtained as compared with other methods of calculation.