## KTK-R-4: Technical Overview The **KTK-R-4** is a high-performance, fast-acting fuse part of the **Limitron™** series, manufactured by Eaton (Bussmann Division). It is specifically designed to provide high-current limitation for control circuits and small motor loads. --- ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Current Rating** | 4 Amperes | | **Voltage Rating (AC)** | 600 Vac | | **Interrupting Rating** | 200,000 Amps (RMS Symmetrical) | | **Fuse Class** | Class CC | | **Response Time** | Fast-Acting | | **Body Material** | Melamine (Fiberglass) tube with Nickel-plated brass endcaps | --- ### 2. Functional Characteristics The "R" in KTK-R indicates that this fuse is **Rejection-style**. This is a critical safety feature in electronic and electrical systems: * **Physical Design:** It features a unique grooved endcap. * **Safety Integration:** This physical shape prevents the installation of lower-rated fuses (like standard midget fuses) into a Class CC fuse holder, ensuring the circuit remains protected at the intended 200kA interrupting level. * **Fast-Acting Performance:** Unlike "Time-Delay" fuses, the KTK-R-4 is designed to open very quickly when it detects an overcurrent. This makes it ideal for protecting sensitive components that cannot withstand prolonged surges. --- ### 3. Common Applications The KTK-R-4 is typically found in industrial and commercial settings where high fault currents are possible: 1. **Control Transformer Protection:** Used on the primary side of control transformers. 2. **Branch Circuit Protection:** Providing localized protection for small loads. 3. **Industrial Control Panels (TCP):** Protecting PLC (Programmable Logic Controller) inputs or sensitive relays. 4. **Lighting Ballasts:** Protecting high-voltage lighting circuits. --- ### 4. Code Compliance The KTK-R-4 meets several international standards to ensure reliability: * **UL Listed:** Guide JDDZ, File E4273. * **CSA Certified:** Class 1422-02, File 53787. * **RoHS Compliant:** Manufactured without hazardous substances.