Analyzer - meter of 230VAC network parameters - single phase.

futek2 27 Oct 2022 21:15 Cool? (+25)

Welcome to those interested in the topic of building a simple analyzer - meter of 230V network parameters - one phase.
The meter is based on ESP32 module according to the schematic diagram, which is attached, and the whole circuit is not complicated.

To build the meter you will need the following parts:
1 - ESP32 DEVKIT V1 module with 4 MB memory, as shown in the attached image;
2 - current measurement sensor - current transformer for 100A range with 1V output or for 25A range with 1V output type SCT013, as shown in the attached image;
3 - sensor for voltage measurement - voltage transformer type TV16, as in the attached image;
4 - 5k precision potentiometer - 2 pieces, as in the attached image;
5 - power supply 230VAC / 5V 0.7A or charger with mini USB plug to power the ESP32 module, as in the diagram;
6 - universal mounting board;
7 - resistors and capacitors as in the diagram;
8 - wires and test leads as in the picture of the whole meter.

Important thing is when buying a
current transformer, please choose the type that has an output of 1V

I bought all the components on a well-known auction site, and the total cost did not exceed the amount of PLN 150.
Enclosed are two versions of the software to upload to the ESP32. The difference is that one is for a maximum range of 25A, and the other is for 100A, depending on which current transformer you buy.

The meter measures and displays the offset of sine waveforms of voltage and current relative to each other. It calculates COS fi, and if an inductive factor is detected, it calculates the capacitance of a capacitor to compensate for it.
Additionally, there is a choice of calculating the THD factor from voltage or current measurements, along with graphs showing harmonic levels - max 9.

Results and graphs are displayed on the screen of a phone, tablet or laptop.
Connect to the meter over Wi-Fi, and the meter has an IP address of 192.168.10.1 - image attached.
The software can be tested as soon as it is uploaded to the ESP32 module without the need to build the entire meter.
Inclosed are images of the following screens and the appearance of the meter.

I don't describe too much, because the design is simple, with which even a beginner in electronics can cope.
All the calculations are contained in the software, with which I was not easy, especially with the counting and measurement of harmonics - I wanted to make it clear and give accurate results.
The screens with the results are refreshed every 5 seconds, and the graphs are plotted using the vector graphics function - SVG.

After building the meter, calibration is done with precision potentiometers.
I calibrated using 2 kettles of 2000Watts each and a digital meter, which is sufficient to set the voltage and current range according to the readings on the meter.
After calibrating, you should mark yourself the voltage end that will be connected to the neutral wire and the other end that will be connected to the phase wire.

After attaching the current sensor to the phase wire, you should put it so that it is in front of the connected voltage wire on the phase.
Connect the meter to the 230VAC network in the sketch drawing, which is attached.
And when you are sure that the measurement of COS fi is correct, you need to mark yourself with a marker the direction of fastening the current sensor to the wire.
I determined this by turning off all loads electricity, and leaving the desktop computer and the meter should show capacitive power factor, if inductive then I will swap the direction of the sensor clasp.
For certainty, you can do some tests on other devices, such as a motor and should show inductive power factor, During calibration using kettles, the power factor should be near 1.

As a housing for the meter, I used a laptop power supply case.

In the meter it is possible to update the soft without removing the ESP32 module, you can upload new soft over WIFI using a browser from the address 192.168.10.1/new as the login window appears to us, then user admin password admin , and then select the correct bin file and wait for a message about successful upload of the software.

I was inspired to do the design and build the meter and write the program code by this article from a couple of years ago - link below:
https://majsterkowo.pl/rejestrator-napiecia-pradu-mocy/

Please give me any comments and suggestions for improvement or changes.

Greetings and I wish you satisfaction with the use of the analyzer - single phase 230 V network parameters meter.

Finally, I suggest calibrating the current measurement to use 75% of the range I for 25A used two electric czjniki 2000Watts each because the measurements will be more reliable.

I think that many colleagues will see what is happening in our home electrical networks, which will contribute to reducing expenses for electricity.

Update-software 28.10.2022
For both versions, a divider has been added - horizontal lines for THD graphs.
Increased number of decimal places for voltage and current.

Update-software 07.11.2022
Added configuration window to be able to connect to a home router and send data to the server.
Link below
https://www.elektroda.pl/rtvforum/topic3929533-30.html#20261095

Update-software 24.11.2022

Description and programs for uploading software to ESP32.
https://www.elektroda.pl/rtvforum/topic3929533-60.html#20300780

Update - soft 10.01.2024

Description and programs for uploading soft to ESP32.
https://www.elektroda.pl/rtvforum/topic3929533-90.html#20878394

Greetings
Futek2

About Author

futek2 wrote 519 posts with rating 225 , helped 2 times. Live in city Częstochowa. Been with us since 2006 year.

Comments

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gulson 27 Oct 2022 21:25

Great, once I bought a few pieces of it, I didn't know that you can do such wonders with it. By the way, contact me on PM for a small gift for the article ;) [Read more]

simw 27 Oct 2022 21:40

Great mini project - though maybe not that mini :) I don't see anything about kilowatt hours in the pictures. It seems that everything is already done to additionally make an energy meter. [Read more]

futek2 27 Oct 2022 21:51

Hello Col. simw . Thank you for the hint when I find some free time to add another version with energy counting in kWh. It is easy at this stage because all measurements are already made by the meter. ... [Read more]

jarekgol 28 Oct 2022 03:21

triac controller? [Read more]

Shadowix 28 Oct 2022 06:42

How is the quality of these measurements? Have you compared them with a decent meter/meter? The webserver is on ESP or is it sent to some MQTT database? [Read more]

^ToM^ 28 Oct 2022 08:09

A very practical device! Congratulations on your ingenuity. I think maybe we could add a grid and scale to the graphs. It's best to be able to turn it on and off. It is then easier to compare waveform... [Read more]

snow 28 Oct 2022 08:32

In the diagram with ESP, I would change the description with the 5VDC power supply on the output not +5V and -5V, but +5V and GND. Or some other way. This power supply does not output -5V. [Read more]

futek2 28 Oct 2022 08:40

Hello. I answer in turn. I had the opportunity to compare the meter with the measurements of the company meter PQM-707 by Sonel. The differences in the indications were at the level of about 1.5%,... [Read more]

__Maciek__ 28 Oct 2022 11:55

Congratulations ! I wonder if the introduction and measurement of the artificial zero voltage (3.3V/2) makes sense? From openenergymonitor sources, they use a low-pass filter to determine this artificial... [Read more]

futek2 28 Oct 2022 13:02

Hello Col. __Matt__ . Choosing this option with a reference voltage of 3.3V /2, I was guided by the parameters of the ADC converters in ESP32. Their parameters are not in the full range linear beginning... [Read more]

shimano73 28 Oct 2022 13:03

Hello, I wanted to download these packages but they have probably been deleted, at least that's the message I receive [Read more]

futek2 28 Oct 2022 13:22

Maybe it was when I updated [Read more]

Janusz_kk 28 Oct 2022 15:19

I downloaded the code and there is a bin, so we have an advertisement again or a substitute for the project because the author is ashamed of his code. [Read more]

kris8888 28 Oct 2022 15:39

I have a question why on most of the attached screenshots the apparent power expressed in VA does not exactly coincide with the product of the current and voltage values? Similarly, multiplying the given... [Read more]

__Maciek__ 28 Oct 2022 16:07

@futek2 That's not what I meant in terms of 3.3V/2. (I know that the ADC in ESP32 leaves a bit to be desired) rather why are you measuring - I think so based on the diagram, and you don't use a... [Read more]

khoam 28 Oct 2022 16:19

I also don't like it a bit, especially since the Arduino libraries he used are under the LGPL license. They too were "served on a plate" and are someone's intellectual property. How did you... [Read more]

futek2 28 Oct 2022 16:22

Responding wheels. kris8888 is to inform you that the calculations are exactly done. But I send the results on the website with one decimal place. But if you have such a wish, then at your request there... [Read more]

kris8888 28 Oct 2022 16:33

Well, but it's not about the decimal places, because even taking the data from the first discharge where we have U=236V, I=10.4A, the apparent power should be 2454 VA and it is given as 2452 VA. In... [Read more]

futek2 28 Oct 2022 17:02

Col. kris8888 you say, and you have. No problem is also update each version. I think I would leave the rest of the results because it's not a laboratory after all. Regards. Futek2 [Read more]

FAQ

TL;DR: ±1.5 % accuracy “even a beginner can cope” [Elektroda, futek2, #20256375; #20255939]. The DIY ESP32 analyser logs voltage, current, THD (9 harmonics) and COS φ every 5 s via Wi-Fi. Why it matters: you can spot reactive-energy penalties before the bill arrives.

Quick Facts

• Cost of parts ≈ PLN 150 (≈ €35) [Elektroda, futek2, post #20255939]
• Current ranges: 5 A*, 20 A*, 25 A or 100 A selectable by firmware [Elektroda, futek2, #20309777; #20435759]
• Sampling: 4000 points/period at 300 µs, refreshed every 5 s [Elektroda, futek2, post #20256717]
• Accuracy after calibration: ±1.5 % versus Sonel PQM-707 [Elektroda, futek2, post #20256375]
• OTA updates: http://192.168.10.1/new (login: admin/admin) [Elektroda, futek2, post #20255939]

What parameters does the analyser measure?

Voltage (RMS), current (RMS), apparent power, active power, COS φ, THD for up to 9 harmonics, cumulative kWh, 15-minute trend graphs and light-flicker index [Elektroda, futek2, post #20881348]

How accurate are the readings?

After two-point calibration the meter stayed within ±1.5 % of a certified Sonel PQM-707 for both RMS and THD values [Elektroda, futek2, post #20256375]

Which current transformer should I buy?

Choose an SCT-013 with 1 V output; firmware images exist for 5 A, 20 A, 25 A and 100 A versions. Without the 1 V type you risk ADC clipping [Elektroda, futek2, post #20255939]

Do I need precision resistors?

Standard 1 % metal-film parts are sufficient; final accuracy depends on potentiometer calibration rather than absolute resistor tolerance [Elektroda, futek2, post #21188720]

How do I calibrate the meter?

Connect a resistive load using a known multimeter.
Adjust the 5 k potentiometer until voltage matches.
Load to ≥ 75 % of CT range (e.g., two 2 kW kettles) and trim current [Elektroda, futek2, post #20255939]

Why does my graph show noise at zero current?

With the CT shorted the ESP32’s ADC picks up internal noise; readings below ≈ 0.1 A can wander. This does not affect normal loads [Elektroda, futek2, post #20305427]

Can it log data to the cloud?

Yes—enter your router SSID and ThingSpeak API key at http://192.168.10.1/config. The meter pushes voltage, current, COS φ and kWh every 15 s [Elektroda, futek2, post #20259076]

What about MQTT or Home Assistant integration?

Native MQTT is not yet implemented. The author has closed further development, so adding topics would require modifying the closed-source firmware [Elektroda, futek2, post #21295817]

Does it meet TAURON G11 billing conditions?

The analyser resolves COS φ to two decimal places and THD to 0.1 %. That granularity is enough to verify COS φ≥ 0.9 and THD≤ 8 % thresholds stated in typical utility contracts [TAURON T&C, 2023].

Why does the Wi-Fi sometimes drop?

Heavy FFT calculations can starve the Wi-Fi task. ESP32’s FreeRTOS may need balanced priorities; edge cases appear when RSSI < -70 dBm [Elektroda, futek2, post #20296339]

Is the +5 V/-5 V label in the schematic an error?

Yes. The PSU delivers +5 V and GND only; the label has been corrected in later diagrams [Elektroda, snow, post #20256366]

Can I flash the BIN from Linux?

Use esptool.py: esptool --chip esp32 write_flash 0x10000 firmware.bin. Boards often need bootloader at 0x1000 and partition table at 0x8000; ESP_Flasher automates this [Elektroda, jarekgol, post #20298465]

What happens if the ESP32 resets?

Energy counter (kWh) clears to zero; configuration in NVS stays intact. Plan external logging for long-term totals [Elektroda, futek2, post #20294657]

Edge case: will a pure capacitor read correctly?

Early firmware under-reported displacement on a lone 50 µF capacitor (PF ≈ 0.3 vs 0.08 reference) [Elektroda, jarekgol, post #20318198] Later builds (v1.0.8+) fixed the scaling bug [Elektroda, futek2, post #20317802]