The **PEWCT1105** is a high-precision **Current Transformer (CT)** designed for electronic monitoring applications. It is primarily used to measure AC current by converting a high primary current into a proportional, lower secondary current that can be easily read by microcontrollers or measurement ICs. --- ### 1. Key Technical Specifications The following table summarizes the typical electronic characteristics of the PEWCT1105 series: | Parameter | Typical Value | | :--- | :--- | | **Rated Primary Current** | 5A - 20A (Model dependent) | | **Secondary Current** | 2.5mA or 5mA | | **Turns Ratio** | 1000:1 or 2000:1 | | **Accuracy Class** | 0.1 - 0.5 Grade | | **Operating Frequency** | 50Hz / 60Hz | | **Isolation Voltage** | 2500V - 4000V AC | | **Load Resistance** | $\leq$ 100 $\Omega$ | --- ### 2. Functional Components The PEWCT1105 consists of three main electronic elements: 1. **Primary Conductor Hole:** This is the center opening where the wire carrying the load current passes through. It acts as a "single turn" primary winding. 2. **Magnetic Core:** Usually made of high-permeability nanocrystalline or silicon steel. It concentrates the magnetic field generated by the primary wire. 3. **Secondary Winding:** Multiple turns of fine copper wire wrapped around the core. This generates the low-level output signal. 4. **Encapsulation:** The internal components are potted in epoxy resin for moisture protection and high dielectric insulation. --- ### 3. Application Circuit To read the output of the PEWCT1105 with a microcontroller (like an Arduino or ESP32), a **Burden Resistor** must be used to convert the current output into a voltage signal ($V = I \times R$). ```cpp // Basic concept for calculating RMS Current float getSecondaryCurrent(int analogPin) { int rawValue = analogRead(analogPin); float voltage = (rawValue / 1024.0) * 5.0; // Assuming 5V ADC float secondaryI = voltage / BURDEN_RESISTOR; return secondaryI * TURNS_RATIO; // Returns Primary Current } ``` --- ### 4. Advantages & Use Cases * **Safety:** Provides galvanic isolation between high-voltage AC lines and sensitive low-voltage DC circuits. * **Linearity:** Offers a very linear output relative to the input, ensuring high precision across the rated range. * **Compact Design:** Designed for PCB mounting in space-constrained environments. **Common Uses:** * Smart energy meters. * Overload protection circuits. * Industrial motor monitoring. * IoT power consumption tracking.