The **MDL-1/8-R** is a specific model of electronic fuse manufactured by Eaton (formerly Bussmann). It belongs to the MDL series, which is one of the most common standards for small-dimension glass tube fuses used in consumer electronics and industrial equipment. --- ### 1. Technical Specifications The part number "MDL-1/8-R" can be broken down to understand its core ratings: | Feature | Specification | Details | | :--- | :--- | :--- | | **Current Rating** | 1/8 Amp (0.125A) | The maximum continuous current it can carry. | | **Voltage Rating** | 250 VAC | Rated for standard AC line voltages. | | **Response Time** | Time-Delay (Slo-Blo) | Designed to withstand temporary surges. | | **Material** | Glass Tube | Allows for visual inspection of the element. | | **Dimensions** | 1/4" x 1-1/4" | Standard 6.3mm x 32mm physical size. | | **Termination** | Ferrule | Nickel-plated brass end caps. | | **RoHS Compliant** | Yes (The "-R" suffix) | Lead-free and environmentally compliant. | --- ### 2. Key Characteristics #### Time-Delay Functionality The MDL-1/8-R is a **Time-Delay** fuse. Unlike "Fast-Acting" fuses that blow immediately upon reaching the limit, this fuse has a thermal delay. This is critical for circuits that have a high "inrush current" (like motors or large capacitors) where a momentary spike is normal and should not trigger a blown fuse. #### Construction * **Filament:** The internal wire is often coiled or carries a "T-slug" (a small drop of solder) that acts as a heat sink to provide the delay characteristic. * **Interrupting Rating:** At 250VAC, it typically has an interrupting rating of 35A. At lower voltages (125VAC), this increases significantly (up to 10,000A). --- ### 3. Applications Because of its very low amperage (0.125A) and slow-blow nature, it is typically found in: 1. **Control Transformers:** Protecting the primary or secondary windings. 2. **Power Supplies:** Specifically in the input stages of low-power precision instruments. 3. **HVAC Equipment:** Used in thermostat circuits and control boards. 4. **Audio Gear:** Protecting sensitive tube amplifiers or internal circuitry. --- ### 4. Part Number Breakdown `MDL - 1/8 - R` * **MDL:** Series name (Glass tube, Time-delay). * **1/8:** Current rating in Amps (0.125 Amperes). * **R:** RoHS compliant (Lead-free construction). ---