Brown Boveri 401740-K5 800 A Current Transformer

Brown Boveri 401740-K5 is a high-current current transformer (instrument transformer) designed to convert very large primary currents into a safe, low-level secondary signal for metering and protection circuits. The unit is specified for 800 A on the primary side with a 5 A secondary output, aligning with common 800 A/5 A CT configurations used to feed meters and protective relays in electrical distribution systems. As a member of the Brown Boveri BBC lineage, the 401740-K5 suffix identifies a particular variant within the 401740 family, and the part is documented in supplier catalogs and ABB-era literature as a 401740-K5 current transformer. The model appears in distributor catalogs such as Piedmont Dielectrics and Radwell, confirming its status as an 800 A class CT, with related variants like 401740-K4 and 401740-K6 representing different primary/secondary configurations. This current transformer provides a robust means to monitor high-current feeders by delivering a standardized 5 A secondary current to meters or protection relays.