ZMCT103C 5A AC current transformer module — precision current sensing for Arduino
The ZMCT103C is a precision miniature current transformer module designed for non-invasive AC current measurement up to 5A. It produces an output current accurately proportional to the measured AC current, providing galvanic isolation between the high-voltage circuit under test and the low-voltage measurement system. This makes it safe and reliable for use in energy monitoring, power metering, and overcurrent detection applications with microcontrollers like Arduino and ESP32.
Key Specifications:
- Rated input current: 5A AC (peak)
- Rated output current: 5mA (at 5A input)
- Turns ratio: 1000:1
- Frequency range: 50Hz – 60Hz
- Accuracy class: 0.2 (high precision)
- Phase error: ≤20 minutes
- Isolation voltage: 3000V AC (between primary and secondary)
- Operating temperature: -40°C to +70°C
- Package: SIP-3 (3-pin inline)
How It Works:
The AC conductor (live wire) passes through the transformer core as the primary winding. The secondary winding produces a proportional output current (5mA at 5A input). A burden resistor (typically 100Ω–200Ω) converts this to a measurable voltage. A bias voltage and protection circuit are recommended when interfacing with a microcontroller ADC.
Typical Interface Circuit:
- Connect output pins across a burden resistor (e.g. 100Ω)
- Add a DC bias (e.g. 2.5V via voltage divider) to centre the AC waveform for ADC reading
- Add clamping diodes to protect the ADC input
- Read the resulting voltage with Arduino analogRead() and calculate RMS current
Compatible With:
- Arduino Uno, Nano, Mega
- ESP32 and ESP8266
- STM32 and other microcontrollers with ADC
- EmonLib (OpenEnergyMonitor library)
Applications:
- Home energy monitoring systems
- Smart power meters
- Overcurrent detection and protection
- Industrial current logging
- IoT power monitoring nodes