## Overview of the KCE-5D-R The **KCE-5D-R** is a specific model of an **NTC (Negative Temperature Coefficient) Thermistor**. These electronic components are primarily used for circuit protection, specifically to limit **inrush current** in power supplies and other electronic devices. --- ### Technical Specifications Below are the typical electronic characteristics for the KCE-5D-R: | Parameter | Specification | | :--- | :--- | | **Type** | Power NTC Thermistor | | **Resistance at 25°C ($R_{25}$)** | $5\ \Omega$ | | **Max. Steady State Current** | 5.0 Amperes | | **Approx. Resistance at Max Current** | $0.12\ \Omega$ | | **Thermal Dissipation Constant** | $\approx 20\ \text{mW/°C}$ | | **Thermal Time Constant** | $\approx 60\ \text{seconds}$ | | **Operating Temperature** | $-40\text{°C}$ to $+200\text{°C}$ | --- ### How the Electronic Components Work The "5D-R" suffix typically denotes the resistance and the diameter of the component ($5\ \Omega$ resistance and a $13\text{--}15\text{mm}$ disk diameter). 1. **Cold State (High Resistance):** When the device is first turned on, the KCE-5D-R is at room temperature. Its $5\ \Omega$ resistance limits the initial surge of current (inrush) that occurs when capacitors charge up. 2. **Self-Heating:** As current flows through the thermistor, it heats up due to the Joule effect ($P = I^2R$). 3. **Hot State (Low Resistance):** Because it is an NTC device, its resistance drops significantly as it gets hot. This allows the circuit to operate normally with minimal power loss across the thermistor. --- ### Key Applications * **Switching Power Supplies (SMPS):** Prevents blown fuses or tripped circuit breakers during startup. * **AC Motors:** Protects motor windings from high initial current. * **LED Drivers:** Safeguards the delicate electronic ballast components. * **Transformers:** Limits the magnetic inrush current. --- ### Construction Features * **Material:** Made of metal oxide semi-conductive ceramics. * **Coating:** Usually encapsulated in a black or green flame-retardant silicone or epoxy resin. * **Leads:** Radial tinned copper wires for PCB through-hole mounting.