The **FPK-R-20A** is a specialized power fuse, typically used in industrial electrical protection. It belongs to the **Class CC** fuse category, which is known for its high rejection capabilities and current-limiting properties. --- ### Technical Specifications | Parameter | Specification | |:---|:---| | **Fuse Type** | Time-Delay / Slow-Blow | | **Current Rating** | 20 Amperes | | **Voltage Rating** | 600V AC (Standard) | | **Class** | Class CC | | **Interrupting Rating** | 200,000 Amps RMS Symmetrical | | **Termination Style** | Ferrule (Cartridge) | | **Dimensions** | 13/32" x 1-1/2" (Standard Class CC size) | --- ### Key Electronic & Functional Features #### 1. Time-Delay Characteristics Unlike "fast-acting" fuses, the FPK-R-20A is designed to handle temporary surges. This is critical for circuits with inductive loads (like small motors or transformers) that draw a high "inrush" current when first powered on. The fuse will not blow immediately during these brief spikes but will provide protection against sustained overloads. #### 2. Rejection Feature The "R" in the series designation often indicates a **rejection tip**. Class CC fuses have a unique physical physical groove/snub on one end. This ensures that: * They can only be inserted into Class CC fuse holders. * Lower-rated fuses (like Midget fuses) cannot be accidentally swapped into the circuit, maintaining safety standards. #### 3. Current Limitation This part is highly current-limiting. In the event of a massive short circuit, the fuse reacts extremely quickly to stop the flow of electricity before the current reaches its full potential peak. This protects sensitive downstream components from electromagnetic stress and heat damage. --- ### Common Applications * **Control Transformers:** Protecting the primary side of industrial control transformers. * **Motor Branch Circuits:** Providing short-circuit and ground-fault protection. * **Solenoids:** Handling the startup current of electromagnetic actuators. * **Industrial Lighting:** Protection for high-voltage lighting ballasts. --- ### Comparison: Class CC vs. Midget Fuses | Feature | Class CC (FPK-R) | Midget (Generic) | |:---|:---|:---| | **Physical Size** | 10x38mm with Rejection Tip | 10x38mm Flat | | **Interrupting Rating** | Very High (200kA) | Lower (usually 10kA - 50kA) | | **UL Rating** | Branch Circuit Protection | Supplemental Protection Only |