### Overview of the FNQ-R-12 Fuse The **FNQ-R-12** is a high-performance, time-delay industrial fuse part of the **Limitron™** family manufactured by **Bussmann (Eaton)**. It is specifically designed as a "Class CC" fuse, which is a standard for current-limiting fuses used in branch circuit protection. --- ### Technical Specifications | Feature | Specification | | :--- | :--- | | **Amperage Rating** | 12 Amps | | **Voltage Rating (AC)** | 600 Vac | | **Interrupting Rating** | 200 kA 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" (10.3mm x 38.1mm) | --- ### Key Features and Electronic Characteristics #### 1. Current Limiting Ability The FNQ-R-12 is a **rejection-type** fuse. It is designed to physically prevent the installation of lower-rated fuses into the same holder, ensuring that the circuit remains protected at the specified safety level. It limits the high levels of peak surge current to protect downstream components. #### 2. Time-Delay Mechanism Unlike "fast-acting" fuses, the time-delay feature allows for temporary inductive surges. This is critical for circuits involving: * Small motor loads. * Control transformers. * Solenoids. It prevents "nuisance blowing" caused by the high initial inrush current when a device is first powered on. #### 3. High Interrupting Rating With a **200,000 Amp (200kA)** interrupting rating, this fuse can safely extinguish an internal arc even under massive short-circuit conditions, preventing the fuse casing from shattering and causing damage or fire. --- ### Typical Applications 1. **Branch Circuit Protection:** Used in electrical panels to protect specific lines. 2. **Control Transformers:** Often used on the primary side of control power transformers where high inrush currents are expected. 3. **Industrial Control Panels (UL 508):** Used to meet strict safety standards for industrial machinery. --- ### Comparison with Similar Series * **FNQ Series:** Standard 13/32" x 1-1/2" fuses but **not** Class CC (no rejection feature). * **FNM Series:** Midget fuses, usually rated for 250Vac, not suitable for high-voltage branch protection. * **LP-CC Series:** Another Class CC fuse but often used for more general-purpose motor protection.