The **FRS-R-2-1/2** is a specialized industrial fuse belonging to the Fusetron™ series manufactured by Bussmann (Eaton). It is designed for high-performance protection in electrical circuits. ### 1. Technical Specifications Below are the primary technical parameters for the FRS-R-2-1/2: | Feature | Specification | | :--- | :--- | | **Current Rating** | 2.5 Amps (2-1/2 A) | | **Voltage Rating (AC)** | 600 Vac | | **Voltage Rating (DC)** | 300 Vdc | | **Interrupting Rating** | 200,000A RMS Symmetrical (AC) / 20,000A (DC) | | **Fuse Class** | Class RK5 | | **Type** | Dual-Element, Time-Delay | | **Body Material** | Fiberglass tube with brass end caps | --- ### 2. Key Electronic Characteristics #### A. Dual-Element Design Unlike a standard fast-acting fuse, this component contains two distinct elements: 1. **Thermal Element:** Handles low-level overloads. It has a specific time-lag feature that allows temporary surges (like motor starting currents) to pass without blowing the fuse. 2. **Instantaneous Element:** A notched copper link designed to clear short-circuits (high-magnitude faults) almost instantly. #### B. Time-Delay Feature The "Time-Delay" characteristic is critical for inductive loads. It provides a minimum of **10 seconds delay at 500% of the rated current**. This prevents "nuisance blowing" caused by the inrush current of motors or transformers. #### C. Current Limitation As a Class RK5 fuse, it is "current-limiting." This means it can react so quickly during a massive short circuit that it prevents the current from reaching its full peak magnitude, thereby protecting sensitive downstream components from magnetic and thermal stress. --- ### 3. Physical Dimensions (Class R) The "R" in the part number denotes its rejection capability. It features a unique groove in the end cap or a specific notch that prevents it from being replaced by a lower-rated, non-current-limiting fuse (like a Class H fuse). * **Diameter:** Approximately 0.81 inches (20.6 mm) * **Length:** Approximately 5.00 inches (127 mm) --- ### 4. Common Applications * **Motor Branch Circuits:** Used as primary protection for small motors where high startup torque is required. * **Transformer Protection:** Protecting the primary side of control power transformers. * **Panelboards:** General-purpose protection for industrial machinery and HVAC systems.