The **FRN-R-3** is a specific type of industrial fuse within the Fusetron™ series, manufactured primarily by Eaton (Bussmann Division). It is designed to protect electrical circuits from overcurrent and short-circuit damage. ### Technical Specifications | Feature | Specification | | :--- | :--- | | **Model Number** | FRN-R-3 | | **Current Rating** | 3 Amperes | | **Voltage Rating** | 250 Volts AC (up to 125 VDC) | | **Fuse Class** | Class RK5 | | **Interrupting Rating** | 200,000 Amps RMS Symmetrical (AC) | | **Type** | Dual-Element, Time-Delay | | **Physical Size** | 2.0" x 0.56" (Standard Ferrule) | --- ### Key Electronic Components & Features #### 1. Dual-Element Design The FRN-R-3 is a "dual-element" fuse, meaning it contains two distinct mechanisms inside its body: * **The Thermal Element:** Handles low-level overloads. It utilizes a spring-loaded mechanism that melts at a specific temperature, providing a "time-delay" to prevent nuisance tripping from temporary power surges. * **The Short-Circuit Element:** A notched copper or silver link designed to blow almost instantaneously if a massive current spike (short circuit) occurs. #### 2. Time-Delay Functionality This part is engineered to allow high inrush currents (such as those seen when a motor starts) without blowing. For a 3-amp fuse, it can hold 500% of its rated current for a minimum of 10 seconds. #### 3. Rejection Feature (Class RK5) The "R" in the model name indicates a "rejection" physical design. This prevents a user from accidentally replacing it with a lower-quality or lower-rated fuse (like a Class H fuse). It features a specific groove in the cap that fits into Class R fuse clips. --- ### Common Applications Due to its 3A rating and time-delay characteristics, the FRN-R-3 is typically used for: * **Small Motor Protection:** Protecting small fractional horsepower motors. * **Control Transformers:** Safeguarding the primary or secondary side of industrial control transformers. * **Branch Circuits:** General purpose lighting or appliance circuits where a 250V limit is applicable.