## Electronic Analysis of the DDS-CJS-R2 The **DDS-CJS-R2** is a specific iteration of a digital, single-phase, two-wire static electricity meter (Energy Meter). It is designed to measure active energy consumption in residential or light industrial environments. Below is a breakdown of the core electronic components and their functions. --- ### 1. Core Component Categories | Component Class | Specific Part/Function | Description | | :--- | :--- | :--- | | **Microcontroller (MCU)** | Specialized Energy Metering IC | Usually a dedicated SoC (System on Chip) with built-in Analog-to-Digital Converters (ADCs). | | **Power Supply Unit** | Capacitive Dropper or Transformer | Steps down AC mains voltage to 5V or 3.3V DC for the internal logic. | | **Current Sensor** | Manganin Shunt or Current Transformer (CT) | Measures the current flowing through the phase wire. | | **Voltage Sensor** | Resistor Divider Network | Scales down the high AC voltage to a level readable by the IC. | | **Display** | LCD (Liquid Crystal Display) | Typically 5+1 or 6+1 digits to show total kWh. | | **Communication Interface** | Pulse Output (S0) / Optocoupler | Provides an isolated electrical pulse for remote reading or calibration. | --- ### 2. Functional Circuit Breakdown #### A. The Metering IC The heart of the R2 model is typically a high-precision metering chip (such as the **ADE series** or **BL09 series**). This chip: * Multiplies the instantaneous voltage and current values. * Integrates the product over time to calculate active power (Watts). * Converts power data into a frequency pulse used to drive the counter. #### B. The Sensing Stage 1. **Current Measurement:** In the R2, a high-precision **Manganin shunt** is common because it is cost-effective and resistant to magnetic tampering. It produces a small millivolt signal proportional to the current. 2. **Voltage Measurement:** A high-resistance divider ensures that the electronic components are not exposed to 230V directly while allowing the chip to monitor voltage fluctuations. #### C. Data Storage (EEPROM) To ensure data is not lost during a power outage, the R2 includes a **Non-volatile Memory (EEPROM)** chip. This stores the current kWh reading so that when power returns, the meter resumes from the last known value. --- ### 3. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Rated Voltage** | 220V - 240V AC | | **Current Range** | 5(60)A or 10(100)A | | **Accuracy Class** | Class 1.0 or Class 2.0 | | **Frequency** | 50Hz / 60Hz | | **Pulse Constant** | 1000 - 3200 imp/kWh | --- ### 4. Safety & Protection Components * **Varistor (MOV):** Protects the internal electronics from high-voltage surges (lightning or grid switching). * **Optocoupler:** Provides galvanic isolation between the high-voltage internal circuit and the low-voltage pulse output terminals. * **Anti-Tampering Features:** Some R2 variants include sensors to detect if the meter cover is opened or if a magnetic field is applied to bypass measurement.