The **FNQ-R-7-1/2** is a high-performance, industrial-grade fuse. It belongs to the **Limitron™** family and is specifically designed to handle the high inrush currents typical of control transformers and inductive loads. ### 1. Technical Specifications The following table summarizes the key electrical and physical characteristics: | Property | Specification | | :--- | :--- | | **Part Number** | FNQ-R-7-1/2 (or FNQ-R-7.5) | | **Amperage Rating** | 7.5 Amps | | **Voltage Rating (AC)** | 600 Vac | | **Interrupting Rating** | 200,000 Amps RMS Symmetrical | | **Fuse Class** | Class CC | | **Response Characteristic** | Time-Delay (Slow-Blow) | | **Dimensions** | 13/32” x 1-1/2” (10.3 x 38.1mm) | | **Body Material** | Melamine (Fiberglass) tube with Nickel-plated brass endcaps | --- ### 2. Key Features and Components * **Rejection Feature:** As a **Class CC** fuse, it features a physical "rejection tip" (a small nub on one end). This prevents the installation of lower-rated fuses (like Midget fuses) into a Class CC fuse holder, ensuring the safety level of the circuit is maintained. * **Time-Delay Element:** The internal "dual-element" construction allows the fuse to withstand temporary current surges (inrush) without blowing. This is critical for motors and transformers that pull high current for a fraction of a second upon startup. * **High Current Limitation:** It is a "current-limiting" fuse. In the event of a massive short circuit, it reacts fast enough to stop the current before it reaches its full destructive peak, protecting sensitive downstream components. --- ### 3. Common Applications The FNQ-R-7-1/2 is primarily used in industrial environments for: 1. **Branch Circuit Protection:** Safe distribution of power. 2. **Control Transformers:** Handling the high "magnetic inrush" current when a transformer is first energized. 3. **Solenoids and Inductors:** Protecting components that involve coils and magnetic fields. --- ### 4. Cross-Reference Table If you are looking for equivalent fuses from other manufacturers, refer to the table below: | Manufacturer | Equivalent Series | | :--- | :--- | | **Bussmann (Eaton)** | FNQ-R-7-1/2 | | **Littelfuse** | KLDR 07.5 | | **Mersen (Ferraz Shawmut)** | ATDR 7.5 |