5. Near-line fault

When the network is inductive, the current is cut off at a time when the voltage is close to its maximum. If the fault is close to the beginning of the line, opening the circuit-breaker will cause rapid voltage oscillations along the portion of line between the open circuit-breaker and the fault, due to the high natural frequencies of the line portion. Immediately after the circuit-breaker is opened, these oscillations will cause a very rapid increase in the TTR. The consequences of this phenomenon on circuit-breaker characteristics are explained in