Dear All,
For an Arduino project I need to continuously measure the current variation which will be about 150mA +/- a few mAmps. The Voltage will be about 200Volts DC!
What current sensor can guys recommend. It must be safe as well considering the high Voltage so I guess am ACS712 cannot establish sufficient separation between the low Voltage and the high Voltage side.
A TC-9520256 seems much safer but if I look at the specs it does not support DC.
Thank and regards!
Are you saying that the minimum current is 0 and the maximum 150mA+/-
What kind of resolution do yo need?
Is 1ma OK?
Hi Jim,
Thank you for your reaction and remark.
The 150mA will be drawns constantly when switched om and will not deviate a lot afterwards untill switched off. A 10mA resolution will do, 20mA is also OK. Hope this helps.
Greetings from the Netherlands.
Have you looked at hall sensors? Hall current measurement is a non-contact technique that measures the magnetizing effects of current flowing in a conductor. This technique gives good electrical isolation between the measured conductor and transducer output. It works over a large range and offers fast response to input changes. You may see these in your DC current probes for oscilloscopes.
In that case, neither the TC-9520256 nor the TCS712 would work.
So we need to find a solution.
20mA is a very poor resolution.
Do you just need to know if there is current flowing or not.
For example if the current is above 75mA or not?
We know the drawn current is about 150mA (clampmeter). I need to "proof" that this value does not change a lot. That's all. The current is used for an elektromagnet. We want to log the current draw, just to be sure what the variation in mA's is.
My knowlegde is just not enough for this specific application. There is plenty to find on the net for measuring the current for AC, but not for DC at this Voltage. Thank you for your feedback. If there is anything else you need to know, let me know.
Anything off-the-shelf will be expensive.
This sensor has a 0 to 500mA range with a 0 to 5V output.
Otherwise you will have to build something from scrach.
One approach could be to use a voltage to frequency converter (Analog Device note is here:https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwizsvuVlMX_AhUbh1wKHVTBBkwQFnoECBIQAw&url=https%3A%2F%2Fwww.analog.com%2Fmedia%2Fen%2Ftraining-seminars%2Ftutorials%2FMT-028.pdf&usg=AOvVaw3z7ou1TbaMKInmXD7SEiGM)
Then use an opto isolator and convert back or measure the frequency with your Arduino.
Read the datasheet. It provides 2.1kV isolation between the current measuring pins and the rest of the circuit. It should be just fine.
Hi CLI,
If that is the case I will try the ACS712, how could I have missed that?
I will keep a non invasive sensor in mind though. It's just so much saver to work with.
Thank you.
For the 5A version of the ACS712, the sensitivity is 185mV/A but the output noise is 21mV.
That's 113mA of noise.
Useless if you are trying to measure 150mA
What are your thoughts on the INA219?
Your answers are much appreciated!
I read now the max Voltage is 26V....
This is not an option.
Correct, not an option.
I don't think that there is a cheap and easy way of doing this. The small current and large DC voltage make it a difficult problem.
Ha, I found this using ChatGPT:
ACS758LCB-050B-PFF-T
What do you think?
Thanks again.
Please, NO ChatGPT
There are ways of doing it but it will require making a custom
PCB
And how is that switched on/off. With a transistor to ground?
Is it possible to add a sense resistor in that ground line.
Can the electromagnet ground be shared with Arduino ground.
Leo..
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