- In an SCR due to over-current, the junction temperature exceeds the rated value and the device gets damaged.
- Over-current is interrupted by conventional fuses and circuit breakers.
- The fault current must be interrupted before the SCR gets damaged and only the faulty branches of the network should be isolated.
- Circuit breaker has long tripping time. So it is used for protecting SCR against continuous over loads (or) against surge currents of long duration.
- Fast acting current limiting fuse is used to protect SCR against large surge currents of very short duration.