The **FRS-15-R** is a high-performance, fast-acting supplemental fuse commonly used in industrial electrical systems. It belongs to the **Fusetron™** series manufactured by Bussmann (Eaton). --- ### 1. Key Technical Specifications Below are the primary electronic characteristics of the FRS-15-R: | Feature | Specification | | :--- | :--- | | **Current Rating** | 15 Amps | | **Voltage Rating (AC)** | 600 Vac | | **Voltage Rating (DC)** | 300 Vdc | | **Interrupting Rating** | 200,000A RMS Symmetrical (VA), 20,000A (DC) | | **Fuse Class** | Class RK5 | | **Response Time** | Dual-Element, Time-Delay | | **Physical Size** | 0.81" x 5.00" (Standard Ferrule) | --- ### 2. Core Electronic Components & Design The "R" in the part number signifies that it is a **Rejection-style** fuse. Its internal architecture consists of two distinct components that allow it to handle different types of electrical faults: #### A. The Thermal Cutout (Time-Delay Element) * **Function:** Handles temporary overloads (e.g., motor startups). * **Mechanism:** It utilizes a spring-loaded solder joint. If a sustained overload occurs, the solder melts, and the spring pulls the circuit open. This prevents "nuisance blowing" caused by momentary surges. #### B. The Instantaneous Element (Short-Circuit Protection) * **Function:** Reacts to massive spikes in current (short circuits). * **Mechanism:** A notched copper or silver link is designed to vaporize almost instantly when current levels exceed the threshold, quenching the arc within the silica sand filler. --- ### 3. Common Applications Due to its **Class RK5** rating and time-delay characteristics, the FRS-15-R is typically used for: 1. **Motor Circuits:** Providing branch circuit protection where high inrush currents are present. 2. **Transformers:** Protecting against primary overcurrent while allowing for magnetizing inrush. 3. **Solenoids:** Managing the high current draw required to actuate coils. 4. **General Feeders:** Used in power distribution panels to protect downstream equipment. --- ### 4. Safety and Compliance * **UL Listed:** Meets UL 248-12 standards for Class RK5 fuses. * **RoHS Compliant:** The "-R" suffix in modern Bussmann parts also indicates compliance with the Restriction of Hazardous Substances. * **Current Limiting:** It significantly reduces the "let-through" energy during a fault, protecting downstream components from mechanical and thermal damage.