### FRS-R-1/4 Fuse Overview The **FRS-R-1/4** is a specialized industrial fuse manufactured by Bussmann (a division of Eaton). It belongs to the **Fusetron™** series and is widely used for protecting electrical circuits from overcurrent and short circuits. --- ### Technical Specifications | Parameter | Specification | |:---|:---| | **Part Number** | FRS-R-1/4 | | **Amperage Rating** | 1/4 Amp (0.25A) | | **Voltage Rating (AC)** | 600 Vac | | **Voltage Rating (DC)** | 300 Vdc | | **Interrupting Rating** | 200,000A RMS Symmetrical (AC) / 20,000A (DC) | | **Fuse Class** | Class RK5 | | **Type** | Time-Delay (Dual-Element) | | **Physical Size** | 0.81" x 5.00" (Standard Class R dimensions) | --- ### Key Electronic Components & Design #### 1. Dual-Element Construction Unlike a standard fast-acting fuse, the FRS-R-1/4 features a **dual-element** design. * **Thermal Element:** Handles low-level overloads. It provides a time-delay feature that allows temporary surges (like motor startups) to pass without blowing the fuse. * **Instantaneous Element:** A separate short-circuit element that reacts immediately to high-magnitude faults. #### 2. Class RK5 Characteristics The "R" in the part number signifies its class. These fuses have a **rejection feature**. The end caps are designed so they can fit into Class R fuse holders, preventing someone from accidentally replacing them with a lower-rated fuse (like a Class H). #### 3. Time-Delay Functionality The 1/4 amp rating is very low, but because it is "Time-Delay," it can withstand a current surge of up to 500% of its rated capacity for a minimum of 10 seconds. This is critical for protecting small control transformers or solenoid circuits where initial power-up draws more current than steady-state operation. --- ### Common Applications * **Control Transformers:** Protecting the primary side of small industrial transformers. * **Solenoids:** Providing overcurrent protection for low-wattage inductive loads. * **Motor Branch Circuits:** Used in circuits where high inrush currents are present but the running current is very low. * **HVAC Systems:** Protection for control boards and sensitive power inputs. --- ### Summary of Benefits * **High Interrupting Capacity:** Can safely stop a massive 200kA fault current, preventing equipment explosion or fire. * **Reduced Nuisance Blowing:** The time-delay feature prevents the fuse from blowing during normal, momentary power spikes. * **Current Limitation:** It acts quickly enough during a short circuit to limit the total energy (let-through) that reaches downstream components.