As we know, surge protective device will degrade or even come to end of life over time due to repeated small surges, a single strong surge or sustained overvoltage. And when surge protective device fails, it may create a short circuit condition and cause safety problem in the power system. Thus proper overcurrent protection device is needed to work together with surge protective device.
There are normally two types of overcurrent protection device that used together with SPD for backup protection: circuit breaker and fuse. So, what are their Pros and Cons respectively?
Circuit Breaker
Advantages
- Can be repeatedly used and thus lower the maintenance cost.
Disadvantages
- Have a greater voltage drop when experiencing surge current and thus will lower the SPD’s protection level
Fuse
Advantages
- Less likely to malfunction
- Lower voltage drop at surge current
- The product itself is more cost effective especially for great short circuit current situation
Disadvantages
- After it functions, the fuse has to be replaced and thus increase maintenance cost
So in practice, both devices are used depending on the specific situation.