Let us consider the short circuit transient on a transmission line. Certain simplifying assumptions are made at this stage:
1. The line is fed from a constant voltage source.
2. Short circuit takes place when the line is unloaded.
3. Line capacitance is negligible and the line can be represented by a lumped RL series circuit.
7.6 Transmission line model
With the above assumptions the line can be represented by the circuit model. The short circuit is assumed to take place at t = 0.
The parameter α controls the instant on the voltage wave when short circuit occurs. It is known from circuit theory that the current after short circuit is composed of two parts, i.e.
