Response of Eskom´s MV/LV distribution networks to lightning transients

The response of Eskom´s MV/LV distribution transformers to lightning transients is examined and the results presented. A high frequency transformer model has been derived utilising measurements based on impulse testing techniques for use in ATP for Windows and is used to simulate the transfer of surges from the MV to the LV side. The model reproduces the frequency dependant response of the transformer at its terminals and may be used together with any type of simulated load. Both varieties (i.e. Yznll and Dynll) of the Eskom standard distribution transformer are studied and their individual responses compared. The results have been verified by laboratory measurements.