Any AC line V and I dataloggers for monitoring AC line transients ? Low cost.
Yes. There are inexpensive
AC voltage/current loggers, but there is an important distinction:
- Normal data loggers → record RMS voltage/current every second or so.
- Power-quality/transient recorders → actually capture short-duration voltage spikes, sags, interruptions, etc.
If your objective is
finding intermittent AC-line transients, I'd avoid the $20–$100 energy meters. They generally won't capture a 1–100 µs event.
Low-cost options worth considering
TRIPLETT ACDL200 Dual-Input AC Voltage/Current Datalogger
$299.95•Dual-input logger for AC voltage/current, compact design.
REED R5003 Dual-Input AC Voltage/Current Datalogger
$350.99•High-capacity AC voltage/current datalogger, suitable for heavy-duty use.
TRIPLETT ACDL100 AC Voltage/Current Datalogger
$238.06•Affordable dual-input AC voltage/current logger with RMS measurement.
Extech DL160 AC Voltage/Current Datalogger
$449.00•Premium AC voltage/current datalogger with advanced features.
Give feedback
Triplett ACDL200 is probably the one I'd investigate first if you want inexpensive
voltage + current logging. It's around $300 and records up to 131,000 measurements with both inputs. But it is fundamentally a
TRMS logger, not a high-speed transient recorder.
The inexpensive meters around $15–$50 can measure things such as voltage, current, watts, PF and kWh, but I would
not trust them to catch a transient. For example, the inexpensive AC energy-meter modules are designed for energy monitoring rather than waveform capture.
If you specifically want transients
This is where things get more interesting.
The PowerSight
PS4500, for example, explicitly captures fast transients down to about
8 µs, in addition to recording RMS voltage/current.
That's much closer to what I think you're describing.
But there's another possibility that may be much more interesting for you:
Build a very inexpensive transient logger
Since you're comfortable with ESP32/electronics, I would seriously consider building one.
For example:
120 VAC → isolated voltage transformer → attenuator → ADC
and
AC line current → CT → burden resistor → ADC
Then have an ESP32 continuously sample both channels at perhaps
20–100 kS/s, maintaining a circular buffer.
When voltage exceeds a programmable threshold, save:
- 1–2 cycles before the event
- the complete transient
- 5–20 cycles afterward
- peak voltage
- RMS voltage
- current
- timestamp
That would let you distinguish things like:
- motor switching spikes
- compressor startup
- utility switching
- voltage sags
- generator switching
- lightning-induced disturbances
- brief interruptions
- load-induced voltage dips
And the hardware could potentially be
well under $100.
One particularly useful approach would be to have
two separate recording rates:
Slow channel: 1 sample/sec or 10 samples/sec for days/weeks
Fast channel: 50–200 kS/s, triggered only when something abnormal occurs.
That gives you long-term logging
and transient capture without filling the memory.
For comparison, professional equipment gets expensive very quickly: the Fluke 1750, for example, uses 5-MHz waveform capture for short events.
If you tell me
120 V single-phase, 240 V, or both, and approximately
how much current (15 A, 30 A, 100 A, etc.), I can find you the
cheapest commercial logger that actually has a reasonable chance of catching the transients you're interested in.
single phase, 120
For
120 V single-phase, there are some options, but if your primary objective is
catching line transients, I'd narrow the field considerably.
Best low-cost commercial choices
Triplett ACDL200 Dual-Input AC Voltage/Current Datalogger
$299.95•Dual-input logger for AC voltage and current monitoring.
Triplett ACDL100 AC Voltage/Current Datalogger
$329.99•Compact device for true RMS AC voltage and current logging.
Triplett ACDL100 True RMS AC Voltage/Current Datalogger
$120.99•Affordable RMS AC voltage/current datalogger for electrical testing.
Give feedback
The
Triplett ACDL200 is interesting because it can log both voltage and current simultaneously. However, it is primarily a
True-RMS data logger, not a high-speed transient recorder.
For comparison, the AEMC PQL 120 is specifically designed for a 120-V receptacle and samples at
128 samples/cycle (about 7.68 kS/s at 60 Hz), with automatic capture of worst-case surge/sag waveforms. It records voltage and current as well as power-quality parameters.
That's much more appropriate for your application, but it is around
$895, so it isn't really "low cost."
An interesting $450 alternative
The
Powertronics PQR D50 is considerably cheaper than the AEMC. It is specifically a
120/240-V voltage disturbance recorder and records:
- spikes
- sags
- surges
- dropouts
- power failures
- high-frequency noise
- common-mode noise
- frequency
It stores up to
32,000 disturbances and also logs one-minute averages for up to 22 days. Current isn't measured, though.
But I think there's a better solution for you
Given your electronics background, I'd seriously consider a
small DIY transient recorder rather than spending $400–900.
For 120 VAC, I'd make it:
AC line
→ isolated 120-V-to-low-voltage transformer
→ precision rectifier/attenuator
→ ADC
and:
Line current
→ split-core CT
→ burden resistor
→ ADC
Then use an ESP32-S3 to continuously sample both.
I'd target something like:
10–20 kS/s minimum, preferably
50–100 kS/s
with a circular buffer containing perhaps
1 second of data.
When the voltage exceeds, say,
135 V peak/RMS threshold, the ESP32 saves:
500 ms before event + 1–2 seconds after event
to an SD card.
That would let you actually look at the waveform of the disturbance rather than merely being told "a surge occurred."
For your application, I'd also make the trigger programmable for:
- voltage > threshold
- voltage < threshold
- sudden ΔV
- current > threshold
- simultaneous voltage sag + current increase
- loss of AC
- excessive HF noise
And importantly,
don't connect the ESP32 ADC directly to the AC line. Use an appropriately rated isolation transformer or certified isolated voltage sensor and proper fusing/enclosure.
If you want, I can look specifically for
an inexpensive <$100 120-V transient recorder/module that already has an isolated AC input, rather than a normal RMS logger. That may be the sweet spot.
Any Arduino projects out there that might serve
Yes. There are several Arduino/ESP32 projects that are quite close to what you're looking for. The key is to distinguish
power/energy monitoring from
actual transient capture.
The most interesting one I found
ESP32 Power Meter — high-frequency waveform recording
This one is particularly relevant. The project specifically says its objective is to
record high-frequency voltage and current waveforms, rather than just calculate RMS voltage/current. It evolved from ESP8266 hardware to an ESP32 design with local storage and an RTC.
This is much closer to what you want.
You could adapt it for:
- 120 VAC
- 60 Hz
- voltage waveform
- current waveform
- continuous circular buffer
- trigger on abnormal voltage
- save waveform surrounding the event
Another good starting point
ESP32 Smart AC Power Monitor
This uses an
ESP32 + ZMPT101B voltage transformer + ACS712 current sensor and calculates RMS, peak, power, PF, frequency, crest factor, etc.
It's more of an energy/power monitor, but the underlying sampling code could be modified for transient recording.
OpenEnergyMonitor approach
The
OpenEnergyMonitor/EmonLib ecosystem is another good starting point. There are numerous Arduino/ESP32 implementations using:
- ZMPT101B or small voltage transformer
- SCT-013 current transformer
- Arduino/ESP32 ADC
- waveform sampling
- RMS calculation
One ESP32 implementation I found specifically provides voltage and current waveform measurement and calibration using ZMPT101B + CT sensors.
However,
I wouldn't use EmonLib as the final transient-capture engine. It's optimized for calculating power quantities, not preserving short disturbances.
What I'd build for your particular purpose
Since you have ESP32-S3 hardware experience, I'd actually make a very simple dedicated instrument:
120 VAC
│
┌──────┴──────┐
│ │
Voltage PT Load wire
│ │
│ Current CT
│ │
▼ ▼
Anti-alias Burden amp
filter │
│ │
└──────┬──────┘
│
External ADC
│
ESP32-S3
│
┌─────┴─────┐
│ │
RAM SD
ring buffer storage
I would
not use the ESP32 ADC if the objective is serious transient measurement. An inexpensive external ADC would give you considerably better control over sampling and simultaneous voltage/current measurements.
Sampling rate
For your application I'd start around:
25–50 ksamples/sec/channel
That is enough to see disturbances that are completely invisible to ordinary energy monitors.
For example, at 50 kS/s:
- 60-Hz waveform → ~833 samples/cycle
- 1 ms event → ~50 samples
- 100 µs event → ~5 samples
If you want to investigate very fast switching spikes, I'd go to
200 kS/s or higher.
The really useful feature: pre-trigger capture
I'd make the ESP32 continuously record into a circular RAM buffer:
trigger occurs
↓
... PRE-TRIGGER ...|... POST-TRIGGER ...
↑
event
For example:
500 ms before + 1 second after
When voltage exceeds a programmable threshold, the ESP32 freezes the buffer and writes the event to the SD card.
The file could contain:
Time
Voltage
Current
Then you could import it directly into Excel, Python, MATLAB, etc.
You could trigger on:
- V > 130 V
- V < 105 V
- sudden dV/dt
- current > X amps
- voltage spike
- voltage dropout
- loss of zero crossing
That would be
far more useful for troubleshooting your house wiring/equipment than a conventional $300 RMS logger.
One project I found particularly interesting is the ESP32 power meter above because its stated design goal is specifically
high-frequency voltage/current waveform recording.
If you want, I can go one step further and find
Arduino/ESP32 projects that actually capture and save AC waveforms to an SD card, preferably ones using an
isolated 120-V input and an inexpensive external ADC. That would get us very close to a DIY $50–$100 transient recorder.
