S&C Electric Company 121300-R4 SM-4 Refill Unit Power Fuse

S&C Electric Company’s 121300-R4 SM-4 Refill Unit is a replacement power fuse element designed for use in SM-4 fuse holders. It is rated for 7.2 kV nominal operation (8.3 kV maximum) with a 200E amperage rating, intended for SM-4 Holders rated at 7.2 kV. This refill unit fits SM-4 and SML-4 holders and is listed for SME-4Z mountings, enabling quick restoration of protection in outdoor substations and distribution environments that use S&C’s SM-4 protection scheme. The 121300R4 designation identifies the 7.2 kV version within the SM-4 refill family (the higher-voltage companion is 122300R4, which is 14.4 kV nominal, 17.0 kV max). When a fuse element has operated, the refill unit can be installed to reestablish the protection configuration without replacing the entire holder.