Design, development and application of smart fuses. I

A smart fuse that simulates conventional current limiting characteristics during high current faults and has the inherent ability to self-monitor and the capability to be triggered from an external source has been developed. The smart fuse can be used for both substation transformer and secondary conductor overcurrent protection. The design, development, and application of the smart fuse in medium voltage distribution systems and equipment protective schemes are described. The device allows the medium voltage system to be grounded with a low resistance to minimize ground fault currents while still allowing coordination between upstream and downstream devices. It provides protection against single phasing without sacrificing current limiting features