The **FRN-R-350** is a specific model of industrial power fuse. It belongs to the Fusetron™ family, manufactured primarily by **Eaton (Bussmann Series)**. This component is designed for high-capacity electrical protection in commercial and industrial settings. --- ### Technical Specifications The following table outlines the primary electrical characteristics of the FRN-R-350: | Feature | Specification | | :--- | :--- | | **Brand** | Bussmann (Eaton) | | **Series** | Fusetron™ FRN-R | | **Current Rating** | 350 Amperes | | **Voltage Rating** | 250 Volts AC (and 125V DC) | | **Interrupt Rating** | 200,000A (RMS Symmetrical) | | **Fuse Class** | Class RK5 | | **Type** | Dual-element, Time-delay | --- ### Key Electronic Components & Features The "FRN-R-350" is more than just a wire; it is a complex dual-element device: #### 1. Dual-Element Design This fuse contains two distinct internal mechanisms working in series: * **Thermal Element:** Handles low-level overloads. It has a "time-delay" feature that allows for temporary surges (like motor startups) without blowing. * **Magnetic/Short-Circuit Element:** Designed to react almost instantaneously to massive spikes in current (short circuits). #### 2. Rejection Feature (The "R" in FRN-R) The "R" designation signifies that this is a **Rejection Class** fuse. The physical build includes a specific groove or notch in the end cap. This prevents someone from accidentally replacing it with a lower-rated or non-rejection fuse (like a Class H fuse), ensuring the safety integrity of the circuit. #### 3. Current Limitation The FRN-R-350 is "Current Limiting." In the event of a catastrophic short circuit, the fuse reacts so quickly that it prevents the current from reaching its full destructive peak, protecting downstream equipment from heat and magnetic forces. --- ### Common Applications Due to its 350A rating and time-delay characteristics, it is typically used for: * **Motor Branch Circuits:** Where high "in-rush" current is expected during startup. * **Main Service Disconnects:** Serving as the primary protection for a building or large piece of machinery. * **Transformer Protection:** Guarding against primary or secondary surges. ---