### Overview of FG-R04-4BA The **FG-R04-4BA** is a high-precision, fluxgate-based current sensor manufactured by **Magnesensor Technology (MST)**. It is specifically designed for the detection of low-level leakage currents (Residual Current Monitoring) in EV charging stations and solar inverters. --- ### Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Type** | Fluxgate Current Sensor | | **Rated Current ($I_{pn}$)** | 25 mA (Leakage) / up to 40A (Primary load) | | **Supply Voltage ($V_{cc}$)** | +5V DC | | **Output Type** | Analog / Digital (Frequency/PWM options) | | **Frequency Range** | DC to 2 kHz | | **Operating Temperature** | -40°C to +105°C | --- ### Internal Electronic Components and Principles The FG-R04-4BA utilizes the **Fluxgate principle** rather than the Hall Effect, which allows it to detect extremely small DC and AC currents with high stability. #### 1. Magnetic Core and Sensing Coil * **Saturable Core:** Uses a high-permeability magnetic core that is driven into saturation by an internal excitation frequency. * **Detection:** When a leakage current passes through the center hole, it creates a magnetic field that shifts the core's saturation point. The electronic circuit detects this shift. #### 2. Signal Processing ASIC * **Excitation Circuit:** Generates the high-frequency drive signal for the fluxgate. * **Synchronous Demodulator:** Extracts the tiny signal caused by the leakage current from the high-frequency carrier. * **Integrator/Filter:** Smooths the signal to provide a clean DC or PWM output proportional to the leakage. #### 3. Integrated Protection * **Overcurrent Withstand:** Designed to handle high-current surges (typical of power line spikes) without damaging the sensitive measurement electronics. * **EMI Shielding:** Includes internal shielding to prevent interference from the high-current primary conductors passing through the sensor. --- ### Pin Configuration and Connection The device typically features a compact PCB-mount footprint with the following pins: 1. **Vcc:** +5V Power Supply. 2. **GND:** Ground. 3. **Vout:** The analog output voltage representing the detected residual current. 4. **Test/Ref:** A reference voltage or a self-test trigger pin to verify sensor functionality. --- ### Applications * **EV Charging (IC-CPD):** Detects DC 6mA and AC 30mA leakage to meet IEC 62752 standards. * **Solar Inverters:** Monitoring RCMU (Residual Current Monitoring Unit) for safety. * **Industrial Power Supplies:** Ensuring insulation integrity.