ZMPT101B AC voltage sensor: specs and pinout
Breakout built around the ZMPT101B current-type voltage transformer, used to read the shape of an AC voltage through an analog input. The maker document covers the bare transformer only, not the module's amplifier, offset or trimmer.
Variant note. Mains voltage. Connecting the input side of this module to mains wiring, and the enclosure around it, must be done by a qualified person only. The project ideas below cover the low-voltage output side.
Specs
| Spec | Value | Source |
|---|---|---|
| Transformer rating (primary / secondary current) | 2 mA / 2 mA | source p.1 and p.4 section 3.1 Basic parameters (ZMPT101B type A) |
| Accuracy class at rated load | 0.5 % with 100 ohm load | source p.1, p.4 section 3.1 |
| Operating temperature | -40 C to +85 C | source p.4 section 3.1 |
| Humidity (25 C) | 95 % RH max | source p.4 section 3.1 |
| Withstand voltage, primary to secondary | 4 kV for 1 minute, leakage 1 mA max | source p.4 section 3.3 Insulation |
| Insulation resistance | 500 Mohm min at 500 VDC, primary winding to secondary winding and ground terminal | source p.4 section 3.3 Insulation |
| Pins | 4 round pins: P1, P2 (primary), S1, S2 (secondary), 0.8 mm diameter | source p.3 sections 1 and 2 |
Chip pins
These are the pins of the chip on the module, from the chip datasheet. The module's own header may label or expose them differently.
The pin rows describe the bare ZMPT101B transformer. The module board (amplifier, offset, trimmer, header order and supply) is not covered by a maker document, so read the labels printed on your board.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| P1 | Primary input terminal (marked *) | Terminal of the bare ZMPT101B transformer, not the module header. | source p.3 sections 1-2 (outline and schematic) | |
| P2 | Primary input terminal | Terminal of the bare ZMPT101B transformer, not the module header. | source p.3 sections 1-2 (outline and schematic) | |
| S1 | Secondary output terminal (marked *) | Terminal of the bare ZMPT101B transformer, not the module header. | source p.3 sections 1-2 (outline and schematic) | |
| S2 | Secondary output terminal | Terminal of the bare ZMPT101B transformer, not the module header. | source p.3 sections 1-2 (outline and schematic) |
Build with it
Project ideas for the ZMPT101B AC voltage sensor. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- Low-voltage AC waveform viewer: Learning project for reading the shape of the module's analog output on an OLED. The module's mains input side, wiring and enclosure are done by a qualified person only; the beginner's part is the low-voltage output side (module output to the board) and the code. The module's output swing is not in a maker document, so measure the output with a multimeter before connecting it to the Uno, and treat the picture as a waveform shape only.
- AC voltage peak display: Samples the analog input for one cycle and shows the highest value seen. Treat the number as relative, since the module's output swing is undocumented. The module's mains input side, wiring and enclosure are done by a qualified person only; the beginner's part is the low-voltage output side (module output to the board) and the code. Learning project.
- Higher resolution AC sampling: A 16-bit converter gives finer steps on the module's analog output; confirm the output stays between ground and the converter supply before connecting, and treat the result as a waveform shape. The module's mains input side, wiring and enclosure are done by a qualified person only; the beginner's part is the low-voltage output side (module output to the board) and the code. Learning project.
Common mistakes
- The module output is an AC waveform around an offset; an ADC pin only accepts voltages between ground and its supply, and the module's offset and swing are not in a maker document. Measure the output with a multimeter before connecting it to an ADC pin. (source: link covers the bare transformer only)
- Quoting 0.5 % accuracy for the module: the 0.5 % figure is for the bare transformer at a 100 ohm load, not for the module. (source: link, p.4)
- Wiring the module to mains yourself: connecting anything to mains wiring must be done by a qualified person, and the transformer primary side is mains-referenced; no isolation of the module board is documented. (source: general safety practice, not from the datasheet)
Not covered by the official source
- Module-level specs (supply voltage, output offset, output range, trimmer) have no maker document and are not given.
- The maker sheet is in Chinese; values are from pages 1, 3 and 4.
- Listing says 0-250 V: that range is not stated in the maker sheet and is not repeated as a spec.
- The module's output swing at a low AC input voltage is not documented.
Sources
- link (Zeming Langxi ZMPT101B type A approval sheet ZM-JS-CRS25-0482, V1.0, 2025-09-05; Chinese-language)