The **S505-4-R** is a high-performance ceramic body, time-delay (slow-blow) fuse manufactured by **Eaton (formerly Bussmann)**. It is widely used in electronic equipment to protect circuits from overcurrent conditions. --- ## 1. Technical Specifications The following table summarizes the key electrical and physical characteristics of the S505-4-R: | Parameter | Specification | | :--- | :--- | | **Current Rating** | 4 Amperes (4A) | | **Voltage Rating (AC)** | 250 VAC | | **Fuse Type** | Time-Delay / Slow-Blow (T-Type) | | **Body Material** | Ceramic | | **Physical Dimensions** | 5mm x 20mm | | **Breaking Capacity** | 1500A @ 250VAC | | **Resistance (Typical)** | 0.0163 Ohms | | **RoHS Compliant** | Yes (indicated by the "-R" suffix) | --- ## 2. Key Features and Component Breakdown ### A. Ceramic Construction Unlike glass fuses, the ceramic body allows for a much higher **breaking capacity** (interrupting rating). This means the fuse can safely interrupt a short circuit of up to 1500 Amps without the body shattering or exploding. ### B. Time-Delay (Slow-Blow) Characteristic The S505 series is designed to handle temporary "inrush" currents. For example, when a power supply is first turned on, it might briefly draw more than 4A. This fuse will not blow immediately during that brief spike but will open if a sustained overcurrent of 4A or more persists. ### C. The "-R" Suffix In Eaton's nomenclature, the **-R** indicates that the part is fully compliant with **RoHS** (Restriction of Hazardous Substances) standards, meaning it is lead-free. --- ## 3. Common Applications The S505-4-R is commonly found in the following electronic components: * **Power Supplies:** Main input protection for AC/DC adapters. * **Industrial Controllers:** Protection for PLCs and motor starters. * **Consumer Electronics:** High-end audio equipment, televisions, and large appliances. * **LED Drivers:** Protecting the circuitry from surges. --- ## 4. Part Number Decoding `S505` - `4` - `R` * **S505:** Series name (5x20mm, Ceramic, Time-Delay). * **4:** Amperage rating (4 Amps). * **R:** RoHS compliant.