The FRN-R-40 is a 40A Fusetron™ Class RK5 dual-element, time-delay fuse designed for advanced circuit protection. It is rated for 250Vac and 125Vdc, with high interrupting ratings of 200kA AC and 20kA DC. The fuse features a time-delay of at least 10 seconds at 500% of its rated current, making it resilient to temporary motor overloads and surge currents. It is commonly used to provide motor overload, ground fault, and short-circuit protection, helping to prevent motor burnout from overloads or from single-phasing on three-phase systems.