## FNQ-R-8: Technical Overview The **FNQ-R-8** is a high-performance, time-delay fuse belonging to the **Limitron™** family, manufactured by **Bussmann (Eaton)**. It is specifically designed to meet the protection requirements of control transformers and circuits with high inrush currents. --- ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Part Number** | FNQ-R-8 | | **Current Rating** | 8 Amperes | | **Voltage Rating (AC)** | 600 Vac (or less) | | **Interrupting Rating** | 200,000 Amps RMS Symmetrical | | **Fuse Class** | Class CC | | **Response Time** | Time-Delay (Slow Blow) | | **Material** | Melamine tube with Nickel-plated brass endcaps | | **Dimensions** | 13/32" x 1-1/2" (10.3 x 38.1 mm) | --- ### 2. Functional Characteristics #### Time-Delay Feature The "Time-Delay" characteristic is the most critical electronic aspect of the FNQ-R-8. It is engineered to: * **Handle Inrush:** Ignore harmless temporary current surges (like starting a motor or powering a transformer). * **Provide Protection:** Open the circuit quickly if a sustained overload or a high-magnitude short circuit occurs. #### Current Limitation As a **Class CC** fuse, the FNQ-R-8 is "Current Limiting." In the event of a major fault, it reacts fast enough to stop the current flow before it reaches its full potential peak, protecting downstream sensitive electronic components from thermal and magnetic stress. --- ### 3. Physical & Design Elements * **Rejection Feature:** The FNQ-R-8 has a physical "rejection tip" (a specific shape on the endcap). This ensures it can only be used in Class CC fuse holders, preventing the accidental installation of a fuse with lower voltage or interrupting ratings. * **Construction:** The melamine body provides high arc-resistance and structural integrity under extreme heat conditions. --- ### 4. Common Applications * **Control Transformers:** Specifically designed to handle the high inrush currents typical of transformer primary circuits. * **Solenoids:** Protection for inductive loads that pull high initial current. * **Branch Circuit Protection:** Used in industrial panels where space is limited but high interrupting capacity is required. ---