The **FRN-R-450** is a specific model of industrial power fuse. It belongs to the **Fusetron™** series manufactured by **Bussmann (Eaton)**. This component is designed for high-current protection in electrical circuits. ### 1. Technical Specifications The following table summarizes the key electrical characteristics of the FRN-R-450: | Feature | Specification | | :--- | :--- | | **Model Number** | FRN-R-450 | | **Current Rating** | 450 Amperes | | **Voltage Rating** | 250 Volts AC (up to 125 VDC) | | **Interrupting Rating** | 200,000 Amps RMS Symmetrical (AC) | | **Fuse Class** | Class RK5 | | **Response Characteristic** | Dual-Element, Time-Delay | | **Physical Size** | Large blade-style cartridge | --- ### 2. Key Design Elements #### Dual-Element Construction Unlike a standard single-link fuse, the FRN-R-450 contains two distinct components: 1. **Thermal Element:** Handles long-term overloads (e.g., a motor stalling). It allows the fuse to "wait" for brief surges without blowing. 2. **Magnetic/Instantaneous Element:** Acts immediately if a catastrophic short circuit occurs. #### Time-Delay Function This part is specifically engineered to handle **inrush current**. When large motors or transformers start up, they briefly pull much more current than their running rating. The FRN-R-450 will not blow during these normal 1-10 second surges, preventing "nuisance tripping." #### Class RK5 Rejection Feature The "R" in the part number signifies a rejection feature. The fuse has a specific physical notch in the blade. This prevents a user from accidentally replacing it with a lower-rated fuse (like a Class H) that cannot handle the same level of short-circuit energy. --- ### 3. Common Applications The FRN-R-450 is primarily used in heavy industrial and commercial settings: * **Motor Branch Circuits:** Providing both overcurrent and short-circuit protection. * **Main Service Disconnects:** Used in the primary power entrance of a building. * **Transformer Protection:** Guarding against internal faults. * **General Purpose Feeders:** Protecting large gauge wiring from overheating. --- ### 4. Visual Identification Code ```text FRN - R - 450 | | | | | +-- Amperage (450 Amps) | +------- Rejection Style (RK5) +------------ Fusetron (250V Dual-Element) ```