high current and voltage measurement

Thread Starter

Chris.marshall4

Joined Apr 30, 2020
4
Hi all,

I've built a load bank prototype with very simple components that can produce a 20kW load, I currently have a small section of the circuit dedicated to measuring the voltage and current which feeds to an Arduino which displays said information on an LCD. I'm looking for a device that may to able to measure it more effectively and perform all functions itself like a multimeter, must be able display the measured values up to 200A and 400VAC. Thanks in advance!
 

ronsimpson

Joined Oct 7, 2019
684
To measure 200A ac and dc I have used this part.
ACS770
It converts the 200A into a small voltage that can be easy measured. (includes isolation)

Because you are measuring ac volts I would probably use a current transformer.

To measure 400V you can make a voltage divider that reduces the voltage by 10:1.

I have some of these. I & V meter It is not quite right but something to think about.
I also have two of these. more meters The one I have also accumulates power over time. Watts/day or watts/week.
 

Thread Starter

Chris.marshall4

Joined Apr 30, 2020
4
Request diagram schematic photo any of the above in order to provide information
To achieve your goals thank you
1588322922089.png

this is the diagram i have created in multisim, this particular one only shows a 6kW load bank but the rest of the diagram is accurate. if you can see any other glaringly obvious errors with the above design that would also be a huge help!

P.S. ignore the fact that AC is grounded to DC, i was in a rush when i made it and too lazy to change it.
 

Thread Starter

Chris.marshall4

Joined Apr 30, 2020
4
To measure 200A ac and dc I have used this part.
ACS770
It converts the 200A into a small voltage that can be easy measured. (includes isolation)

Because you are measuring ac volts I would probably use a current transformer.

To measure 400V you can make a voltage divider that reduces the voltage by 10:1.

I have some of these. I & V meter It is not quite right but something to think about.
I also have two of these. more meters The one I have also accumulates power over time. Watts/day or watts/week.
 

Thread Starter

Chris.marshall4

Joined Apr 30, 2020
4
Yeah i have something similar in my circuit as it stands, a current clamp and a voltage divider fed to an arduino. i was hoping for an all in one device like the second link you posted but one that could handle the requirements :(
 

Reloadron

Joined Jan 15, 2015
5,455
For 200 Amp 400 VAC it sounds like a commercial application. For both voltage and current did you want true RMS or is Average good enough? I would likely use a current and a voltage transducer with 0 to 5 VDC outputs if you want to feed a uC like an Arduino. AC Current Transducers, AC Voltage Transducers. Those are just some examples. There are similar from other manufacturers out there but they give you an output voltage or current proportional to the measured value. All in one turn key solutions. You can likely also find a complete voltage and current all in one.

Ron
 

schmitt trigger

Joined Jul 12, 2010
242
The question Reloadron has asked you is extremely important.
Do you require average responding measurement which will be converted to RMS values, or do you require an RMS responding measurement.
 

Janis59

Joined Aug 21, 2017
1,179
For high voltage measurements the most important question stands how to insulate the voltage source. Because very often the task is to measure say 12 V plus minus 0,5 V standing on 380 000 Volt higher the ground (like electron microscope filament voltage staying high above common ground of anode). Or make a simultaneous measurements of H-bridge all shoulders voltages and currents against the gates signals, differing a 650V or more over the common ground. All these cases the opto-fiber isolated probe is ultimate answer and be usable with any kind of tester, oscilloscope or whatseverwantto pre-existing on Your shelves.

Sad to tell, all those optos are sth drastically expensive for this reason today. Even most cheapest cost 1,5K but better constructions even 15K. And all options for DIY ends within 10 USD but 100+ MHz. Most extreme I seen end within 300MHz and no over. So I begun to elaborate one up to 1 GHz but this moment I must do other jobs so it waits in the "long shelf".

By the way, it is worth to warn beforehand, if any RF HV measurements may be done, be aware from clearly misleading max kV count on the probes. Typical 1:100 probe have written 3...10 kV max voltage but I have sad experience of dozen , at 300V 100 MHz it burns down in tenth of second. Reason, the marker is true for DC exclusively. At RF the reactive power in front end capacitor is overstepped thousandfold, so it physiclly exploads. And 1: 100 probes are not so cheap thing like a 1:10 probes.
 

tautech

Joined Oct 8, 2019
95
By the way, it is worth to warn beforehand, if any RF HV measurements may be done, be aware from clearly misleading max kV count on the probes. Typical 1:100 probe have written 3...10 kV max voltage but I have sad experience of dozen , at 300V 100 MHz it burns down in tenth of second. Reason, the marker is true for DC exclusively. At RF the reactive power in front end capacitor is overstepped thousandfold, so it physiclly exploads. And 1: 100 probes are not so cheap thing like a 1:10 probes.
You are wrong as you have not taken probe frequency derating into account when working with RF.
The derating curves are listed on every probe datasheet in the probe pouch.

However, the point you raise is correct, probes will explode if you use them outside their rated specs and for RF and low impedance measurements care must be taken that probes are suitable for the task.
 

Reloadron

Joined Jan 15, 2015
5,455
I'm looking for a device that may to able to measure it more effectively and perform all functions itself like a multimeter, must be able display the measured values up to 200A and 400VAC. Thanks in advance!
Now 400 VAC is hardly high voltage so will someone explain to me how we managed to evolve into High Voltage which I see as a voltage > 1,000? While I could be wrong my best guess is we are looking at 50 ~ 60 Hz. I don't really see need for a RF or High Frequency probe either.

Ron
 

Janis59

Joined Aug 21, 2017
1,179
RE: Tautech ""The derating curves are listed on every probe datasheet""
I had bought at least e few ten and different produces. NONE had anything similar a datasheet in the package and even in website I would insult the word "datasheet" if I name so a data they offers.
 
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