### Overview of the LPS-RK-2SP The **LPS-RK-2SP** is a specific model of a Low-Peak, dual-element, time-delay fuse manufactured by **Bussmann (Eaton)**. It belongs to the **Class RK1** family of fuses, which are designed for high-performance circuit protection in industrial and commercial environments. --- ### Technical Specifications Below is a breakdown of the electronic and physical characteristics of the LPS-RK-2SP: | Feature | Specification | | :--- | :--- | | **Current Rating** | 2 Amps | | **Voltage Rating (AC)** | 600 Vac | | **Voltage Rating (DC)** | 300 Vdc | | **Interrupting Rating (AC)** | 300,000 Amps RMS Symmetrical | | **Interrupting Rating (DC)** | 100,000 Amps | | **Fuse Class** | Class RK1 | | **Response Time** | Time-Delay (Dual-Element) | | **Physical Size** | 5.0" x 0.81" (Standard Class R dimensions) | --- ### Key Electronic Components & Design The "SP" in the model name stands for **"Supreme Performance."** The internal design consists of two distinct elements: #### 1. The Thermal Element (Time-Delay) * **Function:** Handles temporary surges, such as motor starting currents. * **Mechanism:** Uses a spring-loaded solder joint. When a sustained overload occurs, the heat melts the solder, and the spring pulls the circuit apart. * **Benefit:** Prevents "nuisance blowing" caused by momentary inrush currents. #### 2. The Magnetic/Short-Circuit Element * **Function:** Reacts almost instantaneously to high-level short circuits. * **Mechanism:** A notched copper or silver link designed to vaporize instantly under extreme fault conditions. * **Benefit:** Provides **Current Limitation**, meaning it clears the fault so fast that the peak current never reaches its full destructive potential. --- ### Key Applications The LPS-RK-2SP is typically used in the following scenarios: * **Motor Branch Circuits:** Protection for small motors where high inrush current is present. * **Transformer Protection:** Shielding the primary side of control transformers. * **Main Switches:** Used in fused disconnects to provide superior coordination (preventing a single fault from taking down an entire facility). * **Arc Flash Mitigation:** Because Class RK1 fuses are highly current-limiting, they significantly reduce the energy released during an arc flash event compared to standard fuses or breakers. --- ### Comparison: RK1 vs. RK5 While RK1 and RK5 fuses have the same physical dimensions, they differ electronically: * **RK1 (LPS-RK):** Lower peak let-through current. Better for protecting sensitive electronics and reducing arc flash risk. * **RK5 (FRN-R/FRS-R):** Higher let-through current. General-purpose protection.