Pulse propagation along multi wire electric fences

Mathematical modelling of electric fence structures for high-voltage (HV) pulse propagation is complex in nature and, as such, electric fence energisers are currently manufactured using empirical rules together with a trial-and-error design approach. With no insight into the behaviour of HV pulse propagation along the fence line, the trend has merely been to develop electric fence energisers that could generate pulses with the highest voltage and the longest pulse duration allowed by the safety standards. Consequently, most current electric fence energisers are over rated and not optimally designed to produce an effective electric shock. An accurate insight into HV pulse propagation is an essential requirement for electric fence design and a semi-analytical technique is proposed to predict the propagation characteristics of HV transient pulses along multi-wire electric fences. The technique models the multi-line fence in frequency-domain to facilitate an analytical solution for the propagation of HV pulses along the fence. A modal transformation is used to decouple the frequency-domain solution, which is then transformed into time domain through a numerical Laplace inversion algorithm to determine the propagation characteristics of the fence at a given location and time. For various line conditions, the propagation of HV pulses is investigated, and the results are presented with comparisons to simulations by power systems computer-aided design to show the validity of theoretical analysis. The technique provides an insight into the propagation characteristics of HV pulses along multi-wire fence lines and thus serves as a tool at the design phase of electric fence energisers.