The **5ST4-R** is a specific model of a **Miniature Cartridge Fuse** commonly used in electronic circuits to provide overcurrent protection. It is part of the 5ST series manufactured by Bel Fuse Inc. ### 1. Technical Specifications The "R" suffix typically denotes compliance with RoHS (Restriction of Hazardous Substances) standards. | Feature | Specification | | :--- | :--- | | **Type** | Glass Body Cartridge Fuse | | **Speed/Characteristic** | Time-Lag (Slow Blow) | | **Size** | 5mm x 20mm | | **Voltage Rating** | 250V AC | | **Current Rating** | Varies (e.g., 500mA, 1A, 4A — depends on full part number) | | **Interrupting Rating** | 35A @ 250V AC | | **Material** | Glass tube with silver-plated brass caps | --- ### 2. Key Characteristics * **Time-Lag (Slow Blow):** Unlike "Fast Acting" fuses, the 5ST4-R is designed to withstand temporary surges or "inrush currents." This makes it ideal for devices with motors or transformers that pull a lot of power for a split second when turned on. * **Physical Dimensions:** The 5x20mm size is the international standard for small electronic devices, making these fuses highly interchangeable. * **Safety Standards:** These fuses are usually UL listed and CSA certified, ensuring they meet rigorous safety benchmarks for electrical fire prevention. --- ### 3. Application Examples The 5ST4-R is found in a wide variety of power supply environments: 1. **Consumer Electronics:** Televisions, audio amplifiers, and power adapters. 2. **Industrial Equipment:** Control panels and small motor circuits. 3. **Medical Devices:** Used in diagnostic equipment where high reliability is required. --- ### 4. Part Numbering Breakdown When looking at the 5ST series, the suffix after the "R" usually indicates the current rating: * `5ST 1-R`: 1 Ampere * `5ST 500-R`: 500 Milliamperes * `5ST 4-R`: **4 Amperes** (if "4" is the specific value provided)