The **LPS-RK-20SPI** is a specific type of high-performance power fuse from the **Low-Peak™** series manufactured by Bussmann (Eaton). It is designed for circuit protection in industrial and commercial environments. --- ### 1. Key Technical Specifications The part number can be decoded to understand its electrical characteristics: | Parameter | Specification | | :--- | :--- | | **Series** | LPS-RK (Low-Peak Time-Delay) | | **Current Rating** | 20 Amps | | **Voltage Rating (AC)** | 600 Vac | | **Voltage Rating (DC)** | 300 Vdc | | **Interrupting Rating** | 300kA RMS Symmetrical (AC) / 100kA (DC) | | **Fuse Class** | Class RK1 | | **Indication** | "SPI" suffix denotes a **SmartSpot** visual indicator | --- ### 2. Functional Components #### A. Dual-Element Construction Unlike standard fuses, the LPS-RK-20SPI is a **dual-element, time-delay** fuse. * **Thermal Cutout:** Handles long-term overloads (e.g., a motor drawing slightly too much current). * **Instantaneous Element:** Acts rapidly (within milliseconds) during a high-magnitude short circuit to prevent catastrophic damage. #### B. The "SPI" SmartSpot Indicator The "SPI" designation is a critical electronic/visual feature. It includes a built-in window that changes color when the fuse has blown. This allows technicians to identify a failed circuit instantly without using a multimeter for every fuse in a panel. #### C. Current Limitation As a **Class RK1** fuse, it is highly current-limiting. In the event of a short circuit, it reacts so quickly that it prevents the current from reaching its full potential peak, significantly reducing the "arc flash" energy and protecting sensitive downstream electronic components. --- ### 3. Common Applications Due to its 20A rating and time-delay characteristics, this part is typically used for: * **Motor Branch Circuits:** Accommodates the high "inrush" current when a motor starts without tripping. * **Transformer Protection:** Resists nuisance blowing from temporary surges. * **Panelboards and Load Centers:** Provides a high level of safety due to its 300kA interrupting rating. --- ### 4. Physical Dimensions The LPS-RK-20SPI follows standard Class RK1 sizing for 0-30A fuses: * **Length:** 5.0 inches (127 mm) * **Diameter:** 0.81 inches (20.6 mm) * **Form Factor:** Cartridge style with cylindrical end caps (ferrule).