Measuring 3 phase Delta AC voltage with an Arduino

Projects General Guidance
1

Hello everyone,

I am working on a project where I want to measure the voltage from a delta type 3 phase generator (3 phases and 1 ground).
The maximum voltage is around 600 volts.
I have been looking on the internet for something to use to measure the voltage but I can't seem to find anything usefull.
Now I was wondering if I could use a module to measure DC voltage and connect the positive side to one of the phases and the other one to another phase or the ground terminal.

Does anyone know if this would work?

Thank you guys in advance!

Daan

2

Are you sure? The peak voltage on AC is 1.414 times the stated RMS voltage.
Paul

3

Hi,
600Vac phase to phase I presume?

You will need to do it so your measurement circuit is isolated from the 3 phases.

A transformer between each phase to reduce the 600Vac down would be advisable.
That primary voltage may be hard to come by, so you may need three 240Vac primary transformers in series in each leg.

This may also help;
https://learn.openenergymonitor.org/electricity-monitoring/voltage-sensing/measuring-voltage-with-an-acac-power-adapter?redirected=true

Can you please tell us your electronics, electrical, programming, arduino, hardware experience?

Thanks... Tom... :grinning: :+1: :coffee: :australia:

4

Thanks for your response.

600 Vac indeed. This is an assumption because the generator will run with variable speeds so the voltage will increase when the rotational speed increases.

I started learing using Arduino 2,5 years ago when I started studying Mechatronics. I have programmed an autonomous vehicle that year. Since then I have played around with a couple of things such as making automatic radiator fans.
I have also transformed an old bike into an electric bike/scooter.
There are more things but I think this gives you guys a good insight.

5

So your peak voltage is nearly 850 volts. Be very careful!
Paul

6

Given the voltages here , I would buy a conventional 3ph meter and take a pulse output if you want to log anything .
By the time you’ve bought transformers etc it will be far cheaper , and probably more accurate….and safer !!

7

What kind of 3 phase meter were you thinking about? Do you have a link to one?

8

Google is your friend ..” polyphase meter”, “ 3ph electricity meter “- lots of companies out there .

9

An important thing that I forgot to mention is that the generator is a 1000kVA / 800 kW generator. The current that it will generate is about 1500 A. And I can't seem to find a 3 phase meter that can handle 1500 A.

10

Thought you wanted to measure voltage?

11

Yes you are right. The only meters I find on Google are kWh meters. Maybe I am looking in the wrong place but I can't find a meter that just measures the 3 phase voltage.

Maybe I am not looking good enough.

12

Time for schematic and link to the generator. Doesn't sound like you are very familiar with 3 phase.

13

You are right that I am not the most experienced person with 3 phase.
I don't have acces to the schematics right now but what do you want to know from the generator?

We will connect cables to the terminals inside the generator and the other end of the cables will go through a current transformer into a control box and from there our load will be connected.

I know that I can measure the voltage by using a simple multimeter and measure between phase 1 and 2, then phase 1 and 3 etc. but the thing is that I need something that can measure the voltage and send it to an Arduino.

14

Apologies here , you did ask for voltage, and I read power !! - in this case you want a suitable voltage transformer to get a lower voltage proportional to the higher voltage . There are devices for this too.

But ..if you have little experience , then maybe you need to employ a suitably qualified person

Example

15

I'd leave out the maybe and insert definetely.

16

Isn't it an option to measure phase to neutral voltage (wich normally is 240 V with 3 phase) and then calculate phase to phase with that measurment?

17

You can just measure phase to phase . If you want phase to virtual neutral use the appropriate scaling factor ( root 3?)

You’d be better off with google again - you can buy 3ph voltmeters too.

18

Does the generator have a neutral connection?

600Vac phase to phase

600/ SQR(3) = 600 / 1.732 = 346Vac. phase to neutral.

If you look you should be able to find 415Vac primary transformers.

Tom.. :grinning: :+1: :coffee: :australia:

19

Yea I know I can buy 3 phase voltmeters but I want to be able to read it with my Arduino.

The generator does have a neutral connection.

20

I just noticed that I forgot to mention that the AC frequency will be variable because the generator will run at different speeds. The frequency will range from about 25 to 75 Hz.