The **FRS-R-15** and **FRS-R-100** are part of the **Fusetron™** series of dual-element, time-delay fuses manufactured by Bussmann (Eaton). These are industrial-grade fuses designed primarily for motor circuits and inductive loads. --- ## Technical Specifications The "15" and "100" in the part numbers represent the **Ampere Rating**. Below is a comparison of their shared and individual characteristics: | Feature | FRS-R-15 | FRS-R-100 | |:---|:---|:---| | **Voltage Rating (AC)** | 600 Vac | 600 Vac | | **Voltage Rating (DC)** | 300 Vdc | 300 Vdc | | **Amperage** | 15 Amps | 100 Amps | | **Interrupting Rating** | 200kA RMS Sym. | 200kA RMS Sym. | | **Fuse Class** | Class RK5 | Class RK5 | | **Type** | Dual-Element, Time-Delay | Dual-Element, Time-Delay | --- ## Key Features & Construction ### 1. Dual-Element Design Unlike a standard fast-acting fuse, these contain two distinct components: * **Thermal Cutout:** Handles long-term overloads (e.g., a motor that is slightly overworked). It allows the fuse to "wait" through temporary surges. * **Short-Circuit Element:** A high-speed link that opens instantly if a massive surge (short circuit) occurs to prevent catastrophic equipment damage. ### 2. Time-Delay Functionality These fuses are engineered to ignore "inrush currents." When a large motor starts, it can pull 5-6 times its normal operating current for a few seconds. The FRS-R series will not blow during this brief period, preventing "nuisance blowing." ### 3. Rejection Feature (The "-R") The "R" in the suffix indicates it is a **Rejection Style** fuse. * The ferrule or blade has a specific notch/groove. * This prevents a user from accidentally installing a lower-rated fuse (like a Class H or K) into a Class R fuse holder, ensuring the safety integrity of the system remains high. --- ## Common Applications * **Motor Protection:** Sized to provide backup overcurrent protection for motors. * **Transformer Protection:** Handles the magnetizing inrush current of power transformers. * **General Feeder Circuits:** Used in industrial panels where high-capacity "short circuit" protection (200,000 Amps) is required. --- ## Comparison of Physical Size Because of the difference in amperage, the physical dimensions vary significantly: * **FRS-R-15:** Typically uses a cylindrical cartridge with "ferrule" ends. * **FRS-R-100:** Uses a larger "knife-blade" terminal structure to handle the 100A heat and current flow.