High Precision 5A AC Current Transformer Sensor – ZMCT103C

Description

The ZMCT103C High Precision AC Current Transformer Sensor is a compact, isolated current sensing module designed for accurate measurement of alternating current (AC) in energy monitoring, load management, and protection applications. Built around the ZMCT103C precision micro current transformer, this module provides a safe, non-contact method of measuring AC current by passing the conductor through the transformer’s center hole, eliminating direct electrical connection to the measurement circuit.

At the heart of the module is the ZMCT103C current transformer, a PCB-mount device with a 1000:1 turns ratio. When the primary AC current flows through the conductor passing through the transformer’s center hole, the secondary winding produces a proportional current. At the rated input of 5A, the output is 5mA . The module includes an onboard sampling resistor that converts this current into a measurable voltage signal, and most versions feature an operational amplifier circuit (such as the OP07 or LM358) to amplify and condition the signal for direct connection to a microcontroller’s ADC input .

The module offers adjustable output via an onboard potentiometer, allowing you to tune the amplification factor (typically 0–100x) for your specific measurement setup. The output signal is an AC voltage waveform that corresponds proportionally to the primary AC current, with the maximum output voltage typically capped at 1/2 VCC to ensure compatibility with standard ADC input ranges . The transformer provides galvanic isolation between the AC line and the measurement circuit, typically rated 3000V to 4500V, ensuring safety when working with mains voltage .

Important Note: This module outputs an analog AC signal, not a DC voltage. To read it with a microcontroller ADC, you must either bias the signal to mid-rail (using a voltage divider or op-amp level shifter) or use a bridge rectifier and filter capacitor to convert it to a proportional DC voltage . The transformer provides galvanic isolation, but proper safety precautions are still required when working with mains AC. The module is not intended for DC current measurement . For precise energy metering applications, calibration against a known reference load is recommended .

Whether you are building a home energy monitor, a solar panel current tracker, or an industrial load monitoring system, the ZMCT103C module provides a reliable, isolated solution for AC current sensing.

Features

• ZMCT103C precision current transformer — 1000:1 turns ratio for accurate AC current sensing

• Galvanic isolation — Separates high-voltage AC line from low-voltage measurement circuit for safety

• Onboard sampling resistor — Converts transformer output current to a measurable voltage signal

• High-precision op-amp circuit (active variants) — Amplifies and conditions the signal for direct ADC input

• Adjustable output — Potentiometer allows tuning of output voltage range

• Wide supply voltage (variant dependent) — Some variants support 3–35V DC operation

• Compact PCB form factor — Approx. 18 × 19mm for easy integration

• Wide linear range — 0–10A (with 100Ω load) for measurement headroom beyond the 5A rating

• High linearity — 0.2% for accurate current-to-voltage conversion

• Wide application range — Energy metering, motor monitoring, overcurrent protection, solar systems

Technical Specifications