The **LPS-RK-350SP** is a specialized high-capacity power fuse, specifically part of the **Low-Peak™** series manufactured by Bussmann (Eaton). It is a Class RK1 dual-element, time-delay fuse designed for heavy-duty industrial applications. --- ### 1. Technical Specifications The following table outlines the primary electronic and physical characteristics of the LPS-RK-350SP: | Attribute | Specification | | :--- | :--- | | **Current Rating** | 350 Amperes | | **Voltage Rating (AC)** | 600 Vac | | **Voltage Rating (DC)** | 300 Vdc | | **Interrupting Rating** | 300 kA RMS Symmetrical (AC) / 100 kA (DC) | | **Fuse Class** | Class RK1 | | **Type** | Dual-Element, Time-Delay | | **Material** | Melamine glass tube with silver-plated copper end caps | --- ### 2. Key Electronic Components & Design While a fuse is often viewed as a single part, the LPS-RK-350SP consists of several critical internal elements that determine its behavior: #### A. Dual-Element Construction This fuse contains two distinct internal mechanisms wired in series: 1. **Thermal Cutout (Time-Delay):** A spring-loaded mechanism designed to handle temporary surges (like motor starting currents). It will not blow if the current spike is short-lived. 2. **Short-Circuit Element (Fast-Acting):** A notched copper or silver ribbon designed to vaporize instantly if a high-magnitude short circuit occurs. #### B. Current Limiting Ability As a **Class RK1** fuse, it is highly current-limiting. This means that in the event of a major fault, it reacts so quickly that it prevents the peak current from ever reaching its full potential, protecting downstream components like circuit breakers and motor starters from explosive forces. #### C. Rejection Feature The "RK" designation indicates a rejection feature. The end caps are designed with a specific notch that allows it to fit into Class R fuse clips, preventing someone from accidentally replacing it with a lower-rated Class H or K fuse. --- ### 3. Common Applications Due to its 350A rating and time-delay characteristics, the LPS-RK-350SP is typically found in: * **Large Motor Circuits:** Handling the high "in-rush" current during startup without nuisance tripping. * **Main Service Disconnects:** Providing a high level of protection for industrial building power entries. * **Feeder Circuits:** Protecting sub-panels in manufacturing facilities. * **Inductive Loads:** Transformers and solenoids that experience momentary surges. --- ### 4. Comparison: RK1 vs. RK5 | Feature | Class RK1 (LPS-RK) | Class RK5 (FRS-R) | | :--- | :--- | :--- | | **Current Limitation** | Superior (Much higher) | Moderate | | **Let-through Energy** | Very Low | Higher | | **Best For** | Modern, sensitive electronics | Standard electrical loads |