The **FRN-R-3-2/10** (often written as FRN-R-3.2 or 3-2/10) is a specific type of industrial power fuse. It belongs to the **Fusetron™** series manufactured by Eaton’s Bussmann Division. Below is a breakdown of its technical specifications and electronic components. --- ## 1. Part Number Breakdown Understanding the nomenclature is key to identifying its capabilities: | Component | Meaning | Description | | :--- | :--- | :--- | | **FRN-R** | Class RK5 | Dual-element, time-delay fuse (National Electrical Code Class RK5). | | **3-2/10** | 3.2 Amperes | The continuous current rating of the fuse. | | **250V** | Voltage Rating | Rated for AC systems up to 250 Volts. | --- ## 2. Technical Specifications This fuse is designed for power distribution and motor protection rather than small electronic PCBs. * **Current Rating:** 3.2 Amps * **Voltage Rating:** 250 VAC (standard), 125 VDC (often rated for DC as well) * **Interrupting Rating (IR):** 200,000 Amps RMS Symmetrical (at 250V). * **Element Type:** Dual-Element (Time-Delay). * **Physical Size:** 2-inch length x 9/16-inch diameter (Standard Cartridge). --- ## 3. Key Features & Internal Design ### Dual-Element Construction Unlike a standard "fast-acting" fuse, the FRN-R-3-2/10 contains two distinct internal components: 1. **Thermal Cutout:** Handles low-level overloads. It has a "time-delay" feature that allows temporary surges (like a motor starting up) to pass without blowing the fuse. 2. **Instantaneous Element:** A notched copper or silver link that reacts immediately to heavy short-circuit currents to prevent catastrophic equipment damage. ### Rejection Feature The "**R**" in FRN-R stands for **Rejection**. The end caps are designed with a specific physical groove. This prevents a user from accidentally replacing it with a lower-rated fuse (like a Class H fuse) that cannot handle the same level of short-circuit current. --- ## 4. Typical Applications Because of its 3.2A rating and time-delay characteristics, it is most commonly found in: * **Small Motor Branch Circuits:** Protecting motors that have a high "inrush" current but a low steady-state run current. * **Control Transformers:** Protecting the primary or secondary side of industrial transformers. * **Solenoids:** Where momentary high current is required to actuate a valve. ---