Please Help me

[karreira89]

Hello everyone!
I would like to know if you could help me! Firstly, I was wondering if the labview has some tool to convert the ac into dc signals without using an external rectifier? Secondly, how is that through an analog signal with N samples can get a digital signal on a pin d board. What I do in my work is: I get a value of an ac current transducer, after I get the signal transforms it into a dc signal. Then I want to compare this value, the value obtained is less than or equal to 5 that I chose the pin is low if the value read by the largest five want the pin board that chose this to high.
Sending what I have done

Please help me!

• best regards
  

Daniel Carreira

[iangbell]

Daniel

First - Anders said - be very careful if you are connecting to anything related to mains power. Make sure you are using the right measurement devices that are rated for the voltages and currents you are sensing and that you use the right safety procedures.

That said, you can measure AC signals using the right data acquisition devices. This does include signals from standard current transformers. Sensitivities vary but I have some that give 100mV per A and some that do 1mV per A.

If you perform a waveform acquisition on a 50/60Hz signal at (at least) 5ksample/s you will have a good representation of the waveform and you can performa many types of analysis on the signal. Perhaps what you want is one of the simplest and that is to determine the RMS of the signal. There is an express VI to do this - Amplitude and Level Measurement in the Signal Analysis Express palette.

If you are interested in electrical power measurements in LabVIEW, take a look at the Electrical Power Measurement Palette available for free download here http://zone.ni.com/devzone/cda/tut/p/id/8652

Ian

[karreira89]

What I'm doing is passing the cord by a current transducer. The transducer "convert" current into voltage. For example, the transducer that I'm allowed to use a current of 100A and gives us a way out, in tension, but it is up to 5V with alternating voltage. My problem is I want to convert these into AC voltage to 5V dc current. But without using a converter ac / dc "outdoor." I want to convert it into the LabView VI. What does the VI BC to AD Estimator? I do not want to convert voltage values very high as 230V switched here in Portugal. The transducer provides low voltage values. Is there any VI to do what I want?

Secondly, how is that through an analog signal with N samples can get a digital signal on a pin d board. What I do in my work is: I get a value of an ac current transducer, after I get the signal transforms it into a dc signal. Then I want to compare this value, the value obtained is less than or equal to 5 that I chose the pin is low if the value read by the largest five want the pin board that chose this to high.
Sending what I have done

Please help me!

Best gards

Please see my VI MELHOR222. I use one DAQ NI USB - 6008

Daniel Carreira

[ChristopherS]

Take a look at this project, is this hardware configuration similar to yours?  A Hall effect sensor?  This projects uses LabVIEW to generate a waveform, but yours is much simple since you're just looking for 5 volts.  I'm not positive that I understand your project though...

http://scienceshareware.com/how-to-measure-AC-DC-current-with-a-hall-effect-clamp-.htm

Hope this was helpful.

[karreira89]

Yes it is similar. What I do is the same as the site that sent me so that my DAQ has acquired the voltage not current. And what makes my transducer is to convert the current to a value of alternating voltage. What I want is to turn the AC voltage into DC voltage. Is there any VI in the labview to do what I want?

[Joel_in_Calif]

Have you gotten this figured out yet?

Sounds like you want to simulate the front end of a power supply (the rectifier portion) and convert the measured AC signal into it's equivalent DC voltage. If so then I'd pretend I had a full wave rectifier and first measure the MAX peak to peak AC voltage and then divide this by Pi (3.1415).  This will give you the equivalent DC voltage.

Good luck,