The **5HF125-R** is a specific type of electronic component, primarily classified as a **High-Breaking Capacity Miniature Glass Body Cartridge Fuse**. It is part of the 5HF series manufactured by companies like **Bel Fuse Inc.** --- ### ## 1. Technical Specifications Below are the primary electrical and physical characteristics of the 5HF125-R: | Feature | Specification | | :--- | :--- | | **Part Number** | 5HF125-R | | **Current Rating** | 125 mA (0.125 Amps) | | **Voltage Rating (AC)** | 250 V | | **Fuse Speed** | Fast Acting (Quick Acting / F) | | **Breaking Capacity** | 1500 A @ 250V AC | | **Body Material** | Glass | | **Size / Dimension** | 5mm x 20mm | | **Termination Style** | Cartridge (Ferrule) | | **RoHS Status** | Compliant (indicated by the "-R" suffix) | --- ### ## 2. Key Features and Meaning of the Suffixes The alphanumeric code provides specific information about the part's build: * **5HF**: Represents the series name. "5H" usually denotes the 5x20mm physical size with high-breaking capacity. * **125**: Represents the current rating in milliamperes (125mA). * **-R**: Stands for **RoHS Compliant**. This indicates the part is manufactured without lead or other hazardous substances restricted by EU environmental standards. --- ### ## 3. Comparison: Fast-Acting vs. Time-Delay The 5HF125-R is a **Fast-Acting** fuse. It is crucial to distinguish this from "Slow-Blow" (Time-Delay) fuses: 1. **Response Time**: It opens (blows) almost immediately when the current exceeds 100% of the rating. 2. **Protection Type**: It is designed to protect sensitive components (like ICs and semiconductors) that cannot withstand even brief surges. 3. **Inrush Current**: It should **not** be used in circuits with high initial power surges (like motors or large transformers), as it will blow prematurely. --- ### ## 4. Common Applications Due to its 5x20mm standard size and low amperage, it is commonly found in: * Power supplies for small electronics. * Test and measurement instruments (multimeters). * Consumer appliances (coffee makers, monitors). * Industrial control panels for low-current signal protection. --- ### ## 5. Safety Standards This part typically complies with international safety standards to ensure reliability: * **UL/CSA**: North American safety listing. * **VDE/Semko/IEC**: European and International standards (specifically **IEC 60127-2**, Sheet 1).