Transmission line models for coordination of surge-protective devices

The distribution of surge currents between an arrester and suppressor that are separated by a transmission line is described. Six different models of transmission lines are used in the calculations: (1) a single inductor, (2) a single resistor, (3) an ideal transmission line, (4) a cascade of lumped RLC elements where the R value accounts only for the DC resistance of the line, (5) a model with transmission line equations for a continuous line including only the DC resistance, and (6) a model with transmission line equations for a continuous line including both the DC resistance and the skin effect resistance. Two different surge waveforms are used in the simulation: the 1.2/50-/spl mu/s wave and the 10/350-/spl mu/s wave that simulates the current in a direct lightning stroke. The current waveshape and total energy deposited in the suppressor varistor are reported. Conclusions are made about the relative accuracy of the various models of transmission lines in this application.<
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