The S&C Electric Company 121300-R3 SM-4 Refill Unit is a high-voltage fuse refill module designed for use in SM-4 and SML-4 holders. It is rated 7.2 kV nominal and 200 A (200E) with a Time-Current Characteristic (TCC) of 153-4, enabling coordination with adjacent protection devices. This refill unit is used to refill a blown fuse in SM-4 installations and is part of S&C’s SM-4 refill family. The 121300-R3 designation exists alongside newer revisions such as 121300-R4 within the same refill-series for SM-4 applications.
