Introduction to Fuse Selection Tables . . . As described previously, the selection of a transformer primary fuse ampere rating and speed characteristic involves consideration of the following factors: • Anticipated normal transformer loading schedule, including daily or repetitive peak loads, and emergency peak loads • Inrush currents, including the combined effects of transformer magnetizing-inrush current and the energizing-inrush currents associated with connected loads (i.e., hot-load pickup), and the long term overcurrent that occurs upon re-energizing the transformer following an extended outage (i.e., cold-load pickup) • The degree of protection provided to the transformer against damaging overcurrents • Coordination with secondary-side as well as other primary-side overcurrent protective devices • Protecting downstream conductors against damaging overcurrents
Introduction to Fuse Selection Tables . . . As described previously, the selection of a transformer primary fuse ampere rating and speed characteristic involves consideration of the following factors: • Anticipated normal transformer loading schedule, including daily or repetitive peak loads, and emergency peak loads • Inrush currents, including the combined effects of transformer magnetizing-inrush current and the energizing-inrush currents associated with connected loads (i.e., hot-load pickup), and the long term overcurrent that occurs upon re-energizing the transformer following an extended outage (i.e., cold-load pickup) • The degree of protection provided to the transformer against damaging overcurrents • Coordination with secondary-side as well as other primary-side overcurrent protective devices • Protecting downstream conductors against damaging overcurrents
