The **MDL-3/4-R** is a specific model of electronic fuse manufactured by **Eaton (Bussmann Series)**. It belongs to the MDL family of small-dimension, glass-tube fuses. --- ### 1. Key Technical Specifications The model number "MDL-3/4-R" provides a complete breakdown of its electrical characteristics: | Parameter | Value / Specification | | :--- | :--- | | **Current Rating** | 0.75 Amperes (3/4 Amp) | | **Voltage Rating** | 250 VAC | | **Fuse Speed** | Time-Delay / Slow-Blow | | **Dimensions** | 1/4" x 1-1/4" (6.3mm x 32mm) | | **Material** | Glass Tube with Nickel-plated Brass Endcaps | | **RoHS Compliant** | Yes (indicated by the "-R" suffix) | --- ### 2. Physical Components The construction of the MDL-3/4-R consists of several critical parts: * **Glass Body:** A transparent cylinder that allows for visual inspection. If the fuse has "blown," the wire inside will often appear broken or the glass will be charred. * **The Element (Internal Wire):** Unlike "Fast-Acting" fuses, the MDL series uses a coiled or weighted wire design. This design allows the fuse to withstand temporary surges (like a motor starting up) without breaking. * **End Caps:** Conductive caps that secure the wire and provide the contact points for the fuse holder or clip. * **Arc-Quenching Material:** While some high-voltage fuses use sand, the MDL-3/4-R typically relies on the air gap within the glass to quench the arc for its rated interrupting capacity. --- ### 3. Usage and Characteristics #### Time-Delay Functionality The most important feature of the MDL-3/4-R is its **Slow-Blow** nature. This means it is designed to ignore short-duration high currents (inrush currents) but will open the circuit if a sustained overload occurs. #### Common Applications * **Consumer Electronics:** Power supplies and audio equipment. * **Industrial:** Solenoids and small motors. * **Appliances:** Protection for control boards. --- ### 4. Cross-Referencing and Alternatives If you are looking for replacements, ensure they match the **3/4 Amp** and **Slow-Blow** ratings. Common equivalents include: * **Littelfuse:** 313.750P * **Bel Fuse:** MDQ 750