The **FNQ-R-4** is a high-performance, current-limiting time-delay fuse belonging to the **Bussmann CC-TRON™** series. These fuses are specifically designed for branch circuit protection, particularly for inductive loads like transformers and motors. --- ## 🛠️ Technical Specifications Below are the primary electronic and physical specifications for the FNQ-R-4: | Feature | Specification | | :--- | :--- | | **Current Rating** | 4 Amperes | | **Voltage Rating (AC)** | 600 Vac | | **Interrupting Rating** | 200,000 Amps RMS Symmetrical | | **Class** | Class CC | | **Fuse Type** | Time-Delay (Slow Blow) | | **Dimensions** | 13/32" x 1-1/2" (10.3 x 38.1 mm) | | **Material** | Melamine tube with Nickel-plated brass endcaps | --- ## 💡 Key Electronic Characteristics ### 1. High Rejection Feature The "R" in the part number signifies a **rejection tip**. This physical feature 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 fuse capable of handling high-fault currents. ### 2. Time-Delay Functionality Because it is a "Time-Delay" fuse, it can withstand high **inrush currents** (temporary surges) without blowing. This is critical for electronic components like: * **Control Transformers:** Which draw massive current for a fraction of a second upon startup. * **Solenoids:** Which require a burst of energy to actuate. ### 3. Current Limitation The FNQ-R-4 is "Current Limiting." In the event of a short circuit, the fuse reacts so quickly that it interrupts the current before it reaches its full destructive peak. This protects downstream electronic components from thermal and magnetic stress. --- ## 🔌 Typical Applications The FNQ-R-4 is commonly found in industrial control panels and electronic systems involving: * **Branch Circuit Protection:** Safe distribution of power to sub-circuits. * **Motor Control Circuits:** Protecting contactors and relays. * **Inductive Loads:** Ideal for circuits where "nuisance tripping" is common with fast-acting fuses. --- ## ⚠️ Comparison: FNQ vs. FNQ-R | Feature | FNQ (Standard) | FNQ-R (Class CC) | | :--- | :--- | :--- | | **Rejection Tip** | No | Yes | | **Interrupting Rating** | 10,000 Amps | 200,000 Amps | | **Usage** | Supplemental protection | Branch circuit protection |