The **MDL-15-R** is a high-performance, time-delay electronic fuse designed for circuit protection. It is part of the MDL series, originally manufactured by Bussmann (now a division of Eaton). --- ### 1. Key Technical Specifications The part number follows a specific nomenclature where **MDL** is the series, **15** is the amperage, and **R** indicates RoHS compliance. | Feature | Specification | | :--- | :--- | | **Current Rating** | 15 Amperes | | **Voltage Rating** | 32V AC / 125V AC (standard for glass tube) | | **Fuse Type** | Time-Delay / Slow-Blow | | **Physical Size** | 1/4" x 1-1/4" (6.3mm x 32mm) | | **Material** | Glass Tube with Nickel-Plated Brass Endcaps | | **Compliance** | RoHS Compliant, UL Listed, CSA Certified | --- ### 2. Internal Electronic Construction Unlike "Fast-Acting" fuses which use a thin straight wire, the MDL-15-R utilizes a specialized internal structure: * **Wound Element:** Often features a coiled wire or a "T-element" construction. This adds thermal mass, allowing the fuse to absorb brief surges of energy without blowing. * **Time-Delay Mechanism:** It is engineered to withstand "inrush currents." For example, when a motor starts, it may draw 30A for a fraction of a second; this fuse will ignore that spike but will blow if a 20A load persists for several seconds. --- ### 3. Application Use Cases Because of its slow-blow nature, the MDL-15-R is typically used in devices with inductive loads: 1. **Consumer Electronics:** Power supplies for older amplifiers or televisions. 2. **Electric Motors:** Small motors that require a surge to start. 3. **Transformers:** Protecting the primary or secondary side of a transformer where magnetic inrush is common. 4. **Industrial Equipment:** Control circuits where solenoids or relays are triggered frequently. --- ### 4. Comparison Table: MDL vs. AGC The **AGC** series is the fast-acting equivalent. It is important to never swap an MDL with an AGC in a circuit designed for surge protection. | Feature | MDL-15-R (Slow-Blow) | AGC-15-R (Fast-Acting) | | :--- | :--- | :--- | | **Response to 200% Overload** | 5 seconds (approx.) | < 0.5 seconds | | **Visual Appearance** | Visible coil or thick wire | Thin, straight wire | | **Primary Use** | Motors / Inductive loads | Resistive loads / Sensitive electronics |