Current Limiting Fuses

The basic principle of current limiting fuses.

Current limiting fuses are high performance protective devices used across a number of applications. Essentially, when the fuse element inside a current limiting fuse has melted, it enacts a powerful level of resistance to reduce the duration as well as the potential damage caused by short circuits and overloads. Other advantages of these fuses include noiseless interruption, no expulsion violence, and of course, high current limiting capabilities. They are available as 250V fuses, 600V fuses, and a wide variety of other voltage and current ratings.

Not all current limiting fuses are created equal.

Most of the fuses you will come across are current limiting fuses. Current limiting fuses, also referred to simply as CLF, are available across most fuse classes including but not limited to Class CC, Class J, Class T, Class RK1, and Class RK5. Each of these can be further categorized into one of three types of current limiting fuses: backup, general purpose, and full range.

Backup current limiting fuses safely interrupt all fault currents between the rated minimum interrupt current and the rated maximum interrupting current. General purpose current limiting fuses interrupt currents that initiate the fuse’s one hour melting time to the maximum rated interrupting current. Full range current limiting fuses will interrupt currents from the minimum value that will melt the fuse element to the maximum interrupting current. Both general purpose and full range current limiting fuses are commonly used for transformer and feeder circuits.