How to Use Current Tranformer: Examples, Pinouts, and Specs

The PZEM PZCT-02 Current Transformer is a device designed to measure alternating current (AC) by producing a reduced current proportional to the current in its primary winding. This allows for safe monitoring and measurement of high AC currents without directly interfacing with the high voltage lines.

• Energy Monitoring Systems: Used in residential, commercial, and industrial settings to monitor energy consumption.
• Power Quality Analysis: Helps in analyzing the quality of power in electrical systems.
• Overcurrent Protection: Used in protective relays to detect overcurrent conditions.
• Smart Grids: Integral part of smart grid systems for real-time monitoring and control.

1. Primary Winding Connection: Pass the conductor carrying the AC current to be measured through the central hole of the current transformer.
2. Secondary Winding Connection: Connect the secondary winding terminals (S1 and S2) to the measurement device (e.g., a microcontroller or an analog meter).
3. Load Resistor: A load resistor is typically connected across the secondary winding to convert the current output to a voltage signal that can be easily measured.

• Safety First: Always ensure the primary conductor is de-energized before installation.
• Proper Sizing: Ensure the current transformer is rated for the maximum current expected in the primary conductor.
• Calibration: Periodically calibrate the current transformer to maintain accuracy.
• Avoid Saturation: Do not exceed the rated current to avoid core saturation, which can lead to inaccurate measurements.

To measure the current using an Arduino UNO, you can use the following setup and code:

1. Pass the AC wire through the PZCT-02.
2. Connect S1 and S2 to a burden resistor (e.g., 100Ω).
3. Connect the burden resistor to an analog input pin on the Arduino (e.g., A0).

const int sensorPin = A0; // Pin connected to the burden resistor
const float burdenResistor = 100.0; // Burden resistor value in ohms
const float calibrationFactor = 0.05; // Calibration factor for the CT

void setup() {
  Serial.begin(9600); // Initialize serial communication
}

void loop() {
  int sensorValue = analogRead(sensorPin); // Read the analog input
  float voltage = sensorValue * (5.0 / 1023.0); // Convert to voltage
  float current = voltage / burdenResistor; // Calculate current
  current = current / calibrationFactor; // Apply calibration factor

  Serial.print("Current: ");
  Serial.print(current);
  Serial.println(" A");

  delay(1000); // Wait for 1 second before next reading
}

1. Inaccurate Readings:
   • Solution: Ensure the burden resistor value is correct and the calibration factor is properly set.
2. No Output Signal:
   • Solution: Check the connections and ensure the primary conductor is carrying current.
3. Overheating:
   • Solution: Verify that the current transformer is not exceeding its rated current.

• Check Connections: Ensure all connections are secure and correct.
• Verify Calibration: Periodically check and recalibrate the current transformer.
• Inspect for Damage: Regularly inspect the current transformer for any signs of physical damage.

By following this documentation, users can effectively utilize the PZEM PZCT-02 Current Transformer for accurate and safe AC current measurement in various applications.