The protective link is an oil-immersed expulsion-type fuse assembly for use in the high voltage circuit of a distribution transformer. The protective link is often used in series with a backup type current limiting fuse where the function of the protective link is to protect the current limiting fuse from low-grade fault currents or to provide isolation of the current limiting fuse after interruption.
The protective link is also used in coordination with the CSP circuit breaker, where the protective link's function is to disconnect a defective transformer from the feeder circuit and to limit the severity of the damage to the transformer in case of an internal fault.