Overvoltage protection circuit`

摘要

An overvoltage protection circuit for preventing voltage and current overload on a telephone line conductor to prevent damage to a SLIC has a first SCR for connecting the conductor to a reference potential and a first trigger operable to switch the SCR from a first, OFF state to a second, ON state. The trigger is voltage-triggered by voltages exceeding a first magnitude on said conductor and current-triggered by voltages exceeding a second magnitude on said conductor, thereby to provide overvoltage protection at two discrete voltage magnitudes.