Non-invasive AC current sensor

[Dennis_Knutson]

What do you have the current sensor clamped onto?

Have you contacted the vendor? You don't have a LabVIEW problem.

[RTSLVU]

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@gazza48h wrote:

i tried that circuit and sevsral simular circuits but cannot get a reading off my multi meter. I cannot understand it?? Any ideas?

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Dennis is right you really do not have a LabView problem. But I will give you some hints. Your current transformer is rated at 1V=30Amps. That means about 0.033V/Amp. So unless you have this placed over a rather large current source it's going to be hard to read with a meter. Also remember that the CT will output an AC voltage.

The Arduino circut sets a 2.5VDC offset, so 0 amps = 2.5VDC and 30 Amps = 2.5VDC with 1VAC riding on top of it.

The software then removes the offset and does an RMS calculation on the ramaing AC component.

[NIquist]

Another hint (that I hope is not necessary ).  You'll need a single wire with current flowing in one direction.  You cannot just clamp it onto the power cord of a lamp for instance. You would need to strip one conductor out and clamp around that.  

[gazza48h]

Thanks for the info. I figured out that i am only reading a current of 1 - 1.5 A which outputs a very low AC voltage of 34mV which my multimeter was unable to read. How will i interface this AC signal with my arduino and labview. Will i have to amplify the signal so the arduino can read it between 0 - 5v but that will still be AC. How do i create a DC signal so i can read it with  my arduino. I dont have great knowledge when it comes to voltage measurments so please bare with me. Any detailed help much appreciated 🙂

[RTSLVU]

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@gazza48h wrote:

Thanks for the info. I figured out that i am only reading a current of 1 - 1.5 A which outputs a very low AC voltage of 34mV which my multimeter was unable to read. How will i interface this AC signal with my arduino and labview. Will i have to amplify the signal so the arduino can read it between 0 - 5v but that will still be AC. How do i create a DC signal so i can read it with  my arduino. I dont have great knowledge when it comes to voltage measurments so please bare with me. Any detailed help much appreciated 🙂

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Did you read my previous posts about using a DC offset or look at the example DC offest circuit and Ardunio code I linked to that uses this exact same sensor?

[gazza48h]

thanks for your help, i built a non inverting op amp to generate my signal for my arduino to read. I came across a problem. All my analog input pins seem to be floating high to low when there no connection to the pin. Therefore when i connect my op amp to my arduino pin the readings are counteracting each other. Therefore i cannot determine my reading from my op amp.Hope i make some sense as its difficult to explain. Really need some help as i cannot get current reading from my tansducer onto my arduino.

[RavensFan]

What do you mean by "counteracting each other"?

Do you mean something like ghosting?  http://digital.ni.com/public.nsf/allkb/C6C7DE575301A379862572DD00480A01

[RTSLVU]

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@gazza48h wrote:

thanks for your help, I built a non inverting op amp to generate my signal for my arduino to read. I came across a problem. All my analog input pins seem to be floating high to low when there no connection to the pin. Therefore when i connect my op amp to my arduino pin the readings are counteracting each other. Therefore i cannot determine my reading from my op amp.Hope i make some sense as its difficult to explain. Really need some help as i cannot get current reading from my tansducer onto my arduino.

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 I have tried to help as much as I could as I have played around with an Arduino and have experience using current sensors. But I hate to say it this is defiantly not a LabView problem. I believe you need to read up on the Arduino and ask your question on an Arduous hardware based board.

Analog in pin description

http://arduino.cc/en/Tutorial/AnalogInputPins

Tutorial on reading analog input with native Arduino code (Wire)

http://arduino.cc/en/Tutorial/AnalogInput

Tutorial on reading analog input with LabView Arduino library

https://decibel.ni.com/content/docs/DOC-16067

LabView community dedicated to LabView Arduino library

https://decibel.ni.com/content/groups/labview-interface-for-arduino

[gazza48h]

Basically i have 2.40v AC comming into my arduino but i cannot pick it up. Why is this?

[RTSLVU]

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@gazza48h wrote:

Basically i have 2.40v AC comming into my arduino but i cannot pick it up. Why is this?

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The analog input pin voltage is limited to 0-5VDC. Anything outside that range will damage your microcontroller.