The **FNQ-R-4/10** is a specific model of industrial fuse. It is a member of the **Limitron™** family produced by Eaton (Bussmann Division). This fuse is highly specialized for power distribution and motor control protection. --- ### 1. Technical Specifications The "4/10" in the part number indicates a current rating of **0.4 Amperes**. | Feature | Specification | | :--- | :--- | | **Current Rating** | 0.4 A (4/10 Amp) | | **Voltage Rating (AC)** | 600 Vac | | **Interrupting Rating** | 200,000 Amps (RMS Symmetrical) | | **Fuse Class** | Class CC | | **Response Characteristic** | Time-Delay (Slo-Blo) | | **Dimensions** | 13/32" x 1-1/2" (10.3 x 38.1mm) | --- ### 2. Key Electronic Characteristics #### A. Rejection Feature (Class CC) The "R" in FNQ-R stands for **Rejection**. Class CC fuses have a physical "rejection tip" (a cylindrical nub on one end). This prevents the installation of lower-rated fuses (like standard midget fuses) into a Class CC fuse holder, ensuring that the circuit remains protected by a high-interrupting capacity fuse. #### B. Time-Delay Functionality Because this is a time-delay fuse, it is designed to handle temporary **inrush currents**. This is critical for electronic components like: * **Control Transformers:** These often have high momentary current spikes when first powered on. * **Solenoids:** Electromechanical parts that require a burst of energy to actuate. #### C. High Current Limitation The FNQ-R-4/10 is "current-limiting." In the event of a catastrophic short circuit, the fuse reacts fast enough to stop the current before it reaches its full peak magnitude, protecting sensitive downstream electronics from thermal and magnetic stress. --- ### 3. Common Applications In industrial electronics, this fuse is typically found in: * **Branch Circuit Protection:** Providing the final line of defense for small loads. * **Control Panels:** Protecting the primary side of control power transformers. * **HVAC Systems:** Used in the circuitry for motors and specialized sensors. --- ### 4. Cross-Reference & Equivalents If you are looking for replacements or equivalents from other brands, they include: | Brand | Series Equivalent | | :--- | :--- | | **Littelfuse** | KLDR.400 | | **Mersen (Ferraz Shawmut)** | ATDR0.4 | ---