The **FRN-R-1/4** is a specific type of industrial-grade electrical fuse. It belongs to the **Fusetron™** series manufactured by Eaton (Bussmann Division). ### 1. Technical Specifications | Feature | Specification | |:---|:---| | **Part Number** | FRN-R-1/4 | | **Amperage Rating** | 0.25 Amps (1/4 Amp) | | **Voltage Rating** | 250 VAC (Volts Alternating Current) | | **Interrupting Rating** | 200,000 Amps RMS Symmetrical | | **Fuse Class** | Class RK5 | | **Response Time** | Dual-Element, Time-Delay | | **Physical Size** | 9/16" diameter x 2" length (Ferrule style) | --- ### 2. Key Characteristics #### A. Dual-Element Design Unlike standard fuses, the FRN-R-1/4 contains two distinct elements: 1. **Short-Circuit Element:** Operates instantly to protect against massive electrical faults. 2. **Overload Element:** Uses a thermal mechanism to allow temporary "surges" or "inrush currents" without blowing. This is why it is called a "Time-Delay" fuse. #### B. Class RK5 Classification Being a Class RK5 fuse means it is a "Current Limiting" device. It is designed to physically prevent the flow of dangerous peak currents during a short circuit, protecting sensitive downstream components from melting or exploding. #### C. Rejection Feature (The "-R") The "R" in the part number indicates a rejection tip. This is a physical design feature on the end cap that prevents a lower-rated fuse (like a Class H fuse) from being installed in a Class R fuse clip, ensuring the safety level of the circuit is maintained. --- ### 3. Common Applications Due to its low amperage (0.25A) and time-delay characteristics, the FRN-R-1/4 is typically used in the following scenarios: * **Control Transformers:** Protecting the primary or secondary side of small industrial transformers. * **Solenoids:** Handling the initial power spike when a solenoid valve opens. * **Small Motors:** Protecting fractional horsepower motors that require a high starting current but a low running current. * **Heating Circuits:** Where minor fluctuations in current are expected but sustained overloads must be stopped. --- ### 4. Direct Equivalents If you cannot find the Bussmann brand, the following parts are electrically identical: * **Littelfuse:** FLNR.250 * **Mersen:** TR0.25R