ZMPT101B AC Voltage Sensor Module for Arduino — 240V Mains Measurement
The ZMPT101B module isolates the mains AC voltage waveform and outputs a scaled analogue signal readable by an Arduino or ESP32 ADC pin. A precision voltage transformer provides galvanic isolation between the mains circuit and your microcontroller — your Arduino measures the AC waveform safely without any direct connection to mains voltage. The output is centred on VCC/2 (around 2.5V at 5V supply) with the AC waveform riding above and below that midpoint.
- ZMPT101B precision transformer — galvanic isolation between mains and MCU
- Measures UK 240V AC — suitable for single-phase mains voltage monitoring
- Analogue output — centred on VCC/2, reads directly on Arduino ADC
- Onboard multi-turn potentiometer — calibrates output amplitude
- 3.5V–5V supply — compatible with Arduino and ESP32
| Specification | Value |
|---|---|
| Transformer IC | ZMPT101B |
| Measurable voltage | Up to 250V AC (UK 240V mains) |
| Output | Analogue, centred on VCC/2 |
| Supply voltage | 3.5V – 5V |
| Isolation | Transformer-based galvanic isolation |
Is it safe to connect the ZMPT101B to UK 230V mains?
The ZMPT101B transformer provides galvanic isolation, meaning the secondary circuit (connected to your Arduino) is electrically separated from the mains. However, working with mains voltage is inherently hazardous. Enclose mains connections in an insulated housing, ensure all mains wiring is rated for the current, and use an earth leakage circuit breaker (ELCB) in your test setup. Only attempt mains connections if you have relevant electrical competency.
How do you calculate RMS voltage from the ZMPT101B output?
Sample the analogue output at high frequency (over 1000 samples per AC cycle), calculate the RMS of the sampled waveform, then apply the calibration factor determined from the potentiometer. The EmonLib library by OpenEnergyMonitor handles this calculation on Arduino and is available in the Library Manager.
Best for
Arduino mains voltage monitoring, energy meter builds, power quality analysers, solar panel AC output measurement, smart home power monitoring, and university electrical engineering lab projects.
Why Kunkune
Shipped from UK stock. 60-day returns, no minimum order. Fast Royal Mail delivery.
Buying in bulk? For orders of 10+ units, contact us for trade pricing.
