The **KWS-R-50** is a specific model of a **High-Speed, Class R Time-Delay Fuse** manufactured by Bussmann (Eaton). It is designed to provide overcurrent protection for electrical circuits, particularly those with high inrush currents or inductive loads. --- ## Technical Specifications The following table breaks down the core electronic and physical characteristics of the KWS-R-50: | Feature | Specification | | :--- | :--- | | **Current Rating** | 50 Amperes | | **Voltage Rating (AC)** | 600 VAC | | **Interrupting Rating** | 200,000 Amps RMS Symmetrical | | **Fuse Class** | Class R (RK1 / RK5 compatible) | | **Response Type** | Time-Delay (Slow Blow) | | **Material** | Melamine tube with brass end caps | | **Dimensions** | Approx. 1.06" diameter x 5" length | --- ## Electronic Components & Construction While a fuse may seem like a simple device, the KWS-R-50 utilizes specific engineering to handle high-power applications: ### 1. The Fusible Link (Element) The internal core is usually made of a copper or silver alloy. In the KWS-R-50, this element is "notched" or shaped to create specific heat points. This allows the fuse to: * **Withstand Temporary Surges:** It won't blow during brief motor startups. * **React to Sustained Overloads:** It melts if the current stays above 50A for a prolonged period. * **Instantaneous Trip:** It snaps immediately during a massive short circuit. ### 2. Arc-Quenching Filler The body of the fuse is filled with high-purity **silica sand**. When the element melts during a short circuit, the sand absorbs the thermal energy and turns into glass (fulgurite), which acts as an insulator to instantly extinguish the electrical arc. ### 3. Rejection Tip (Class R Feature) The "R" in the model name indicates a "Rejection" feature. One end of the fuse has a specific physical groove. This prevents a lower-rated fuse (like a standard Class H fuse) from being installed in a high-protection Class R slot, ensuring the safety of the circuit is never compromised by an inferior part. --- ## Common Applications * **Motor Branch Circuits:** Handling the high inrush current when a motor starts. * **Transformers:** Protecting against primary side surges. * **Industrial Control Panels:** General purpose protection for high-voltage machinery. * **Mains Disconnects:** Used as the primary safety gate in 600V systems.