The **5TT125-R** is a specific type of **Miniature Glass Tube Fuse** manufactured by Bel Fuse Inc. It is designed for overcurrent protection in various electronic circuits. --- ### 1. Technical Specifications The following table outlines the primary electrical and physical characteristics of the 5TT125-R: | Parameter | Specification | | :--- | :--- | | **Current Rating** | 125 mA (0.125A) | | **Voltage Rating (AC)** | 250 V | | **Fuse Type** | Time-Lag (Slow Blow) / Type T | | **Material** | Glass Body, Nickel-Plated Brass Caps | | **Dimensions** | 5mm x 20mm | | **Interrupting Rating** | 35A @ 250V AC / 10,000A @ 125V AC | | **RoHS Compliant** | Yes (Suffix "-R" indicates RoHS compliance) | --- ### 2. Key Features and Behavior The 5TT series is defined by its "Slow Blow" characteristic, which distinguishes it from fast-acting fuses. * **Time-Lag (Slow Blow):** This fuse is designed to withstand temporary surges or "inrush currents" (like those seen when a motor starts or a power supply is turned on) without blowing immediately. It will only open the circuit if the overcurrent persists. * **Visual Inspection:** Since it features a transparent glass body, it is easy to see if the internal filament has melted, indicating a blown fuse. * **Safety Standards:** These fuses are typically UL (Underwriters Laboratories) and CSA certified, ensuring they meet rigorous safety standards for fire and shock prevention. --- ### 3. Common Applications The 5TT125-R is used in low-power electronic devices where sensitive components need protection but initial power spikes are expected: * **Consumer Electronics:** Power supplies for small appliances. * **Industrial Equipment:** Control circuits and low-current instrumentation. * **LED Drivers:** Protecting the driver circuit from sustained overcurrent. --- ### 4. Comparison Table: Fast-Acting vs. Slow-Blow (5TT) | Feature | Fast-Acting (F) | Time-Lag (T/5TT) | | :--- | :--- | :--- | | **Reaction Time** | Instantaneous | Delayed | | **Inrush Handling** | Poor (will blow) | Good (will survive) | | **Primary Use** | Sensitive ICs/Digital circuits | Inductive loads/Transformers | ---