ZHT103 AC current sensor: specs and pinout
The ZHT103 is a through-hole precision current transformer (1000:1) made by Nanjing Zhen Hengtong. The maker sheet covers the bare transformer; the listing is a module built around it.
Specs
| Spec | Value | Source |
|---|---|---|
| Turns ratio | 1000:1 | source Page 1, main technical parameters table (Chinese, read from rendered page) |
| Rated input current | 5 A | source Page 1, main technical parameters table (Chinese, read from rendered page) |
| Rated output current | 5 mA | source Page 1, main technical parameters table (Chinese, read from rendered page) |
| Load resistance | 100 ohm | source Page 1, main technical parameters table (Chinese, read from rendered page) |
| Accuracy class | 0.5 | source Page 1, main technical parameters table (Chinese, read from rendered page) |
| Linear range | 0 A to 10 A | source Page 1, main technical parameters table (Chinese, read from rendered page) |
| Phase shift | 30 minutes of arc or less | source Page 1, main technical parameters table (Chinese, read from rendered page) |
| Frequency range | 0.02 kHz to 10 kHz (parameters given at 50-60 Hz mains frequency) | source Page 1, main technical parameters table (Chinese, read from rendered page) |
| Isolation withstand voltage | 3200 V per minute | source Page 1, main technical parameters table (Chinese, read from rendered page) |
| Operating temperature | -35 C to +75 C | source Page 1, main technical parameters table (Chinese, read from rendered page) |
Power
| Value | Source | |
|---|---|---|
| Supply | None: passive transformer, no supply pin on the bare part | source Page 1, main technical parameters table (Chinese, read from rendered page) |
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.
Pins above are those of the bare ZHT103 transformer. The module board (any burden resistor, bias circuit, amplifier or header) is not covered by an official document, so the module's output signal and voltage range are unknown.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| 1 (marked *) | Secondary output pin, same-polarity end | Rated output 5 mA | Pin 1 to pin 2 spacing 12.0 mm; pin diameter 0.9 mm | source Page 1 bottom-view drawing |
| 2 | Secondary output pin | Second secondary terminal | source Page 1 bottom-view drawing | |
| P1 (marked *) / P2 | Primary: conductor passes through the 5.0 mm through-hole | Rated input 5 A | '*' marks same-polarity ends | source Page 1 drawing |
Build with it
Project ideas for the ZHT103 AC current sensor. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- AC load current logger: Only the low-voltage side is for the builder; a qualified person makes the mains connection. The stocked module's output stage is undocumented. A bare transformer with a burden gives an AC signal that swings negative, which an ESP32 ADC input (0 V to about 3.3 V) cannot read; unless your module already has a bias stage, add a burden (the sheet specifies 100 ohm, about 0.5 V RMS at 5 A in and 5 mA out) and bias the signal to mid-rail with two equal resistors and a capacitor. Learning project; the mains side is wired by a qualified electrician only.
- Appliance on/off detector: Detects current in an already-installed cable. The stocked module's output stage is undocumented. A bare transformer with a burden gives an AC signal that swings negative, which an Uno ADC input (0 V to 5 V) cannot read; unless your module already has a bias stage, add a burden (the sheet specifies 100 ohm, about 0.5 V RMS at 5 A in and 5 mA out) and bias the signal to mid-rail with two equal resistors and a capacitor. Learning project; the mains side is wired by a qualified electrician only.
- AC current meter on a character display: Sampling the AC waveform in software gives an RMS value. The stocked module's output stage is undocumented. A bare transformer with a burden gives an AC signal that swings negative, which an Uno ADC input (0 V to 5 V) cannot read; unless your module already has a bias stage, add a burden (the sheet specifies 100 ohm, about 0.5 V RMS at 5 A in and 5 mA out) and bias the signal to mid-rail with two equal resistors and a capacitor. Learning project; the mains side is wired by a qualified electrician only.
Common mistakes
- Leaving the secondary unloaded: the sheet specifies a 100 ohm load resistance on the output (source: link, main technical parameters table). General safety note, not stated in the sheet: never leave a current transformer secondary open while current flows through the primary, because it can develop a dangerous voltage.
- Expecting DC readings: it is a transformer specified at 50-60 Hz (0.02-10 kHz range), so it only measures AC (source)
- Running a mains conductor through the hole without a qualified person. General safety note, not from the sheet: mains wiring must be done by a qualified person; the sheet gives no mains-safety guidance.
Not covered by the official source
- The maker's sheet is in Chinese.
- Sheet covers the bare transformer only; the module's onboard circuitry and output voltage are not documented.
- Mains part: wiring must be done by a qualified person.
Sources
- link (Nanjing Zhen Hengtong ZHT103 series datasheet, 1 page, Chinese)