## FRS-R-9: Electronic Component Overview The **FRS-R-9** is a specific model of a heavy-duty industrial fuse. It belongs to the **Fusetron™** series manufactured by **Eaton (Bussmann Division)**. Below is a detailed breakdown of its specifications and electronic characteristics. ### 1. General Specifications The FRS-R-9 is a **Class RK5** current-limiting, dual-element, time-delay fuse. | Attribute | Specification | | :--- | :--- | | **Amperage Rating** | 9 Amps | | **Voltage Rating (AC)** | 600 Vac | | **Voltage Rating (DC)** | 300 Vdc | | **Interrupting Rating (AC)** | 200,000 Amps (RMS Symmetrical) | | **Interrupting Rating (DC)** | 20,000 Amps | | **Class** | RK5 | | **Fuse Type** | Dual-Element (Time-Delay) | --- ### 2. Key Electronic Features #### A. Dual-Element Design The FRS-R-9 contains two distinct components inside the cartridge: * **Thermal Element:** Handles low-level overloads. It provides a "time-delay," allowing temporary surges (like motor startups) to pass without blowing the fuse. * **Instantaneous Magnetic Element:** Responds quickly to high-level short circuits or ground faults to prevent catastrophic equipment damage. #### B. Current Limitation As a Class RK5 fuse, it is "current-limiting." This means that in the event of a major short circuit, the fuse reacts so fast that it clears the fault before the current can reach its full peak magnitude, protecting downstream components from thermal and magnetic stress. #### C. Rejection Feature The "R" in FRS-R stands for **Rejection**. The fuse casing is designed with a specific notch that, when used with an R-Series fuse block, prevents the installation of lower-rated or non-current-limiting fuses (like Class H) into the circuit. --- ### 3. Common Applications The FRS-R-9 is primarily used in industrial and commercial electrical systems for: 1. **Motor Circuits:** Its 10-second minimum time-delay at 500% of the rated current makes it ideal for handling motor inrush currents. 2. **Transformer Protection:** Protects against secondary short circuits. 3. **Main Feeder Switches:** Used in 600V disconnect switches for branch circuit protection. --- ### 4. Dimensions (Physical) While the electronics are internal, the physical form factor is standardized: * **Diameter:** 0.81 inches (approx. 20.6 mm) * **Length:** 5.00 inches (approx. 127 mm)