Surge propagation in high voltage, rural distribution networks from indirect lightning excitation

A survey is made of past work associated with the indirect lightning stroke in relation to the 11 kV rural electricity supply network in this conntry. Facts are established which are considered relevant to this specific type of system with pulse excitation. A complementary field study, based on extensive lightning fault records of a particularly affected area, provides sufficient evidence to establish a characteristic pattern of behaviour to be expected from the network. Each faulted circuit is assumed to be made up of several basic topologies, which are considered as lossless elements, on which single conductor surge analysis is performed by means of a graphical method devised by Bergeron. This is regarded as an efficient first stage assessment of the propagation response, and may be directly compared with the pattern of responses in the field study to explain thosee fault processes due to simple travelling waves alone. The preparation and analysis of a three-conductor circuit is also given some attention. To account for the frequent appearance of anomalous faults, some consideration is given to the influence of local topography associated with the fault, and to a further source of excitation in the form of the prestrike charge which has hitherto been neglected. The study ends with suggestions for the continuation of the work.