Phase Relationship between voltage and Current

I am using LabView 7 Express, and I'm bringing in a two voltage signals (one represents voltage and the other current). I would like view the phase relationship between the two, but I am not sure how because I am still learning the software. So what I really looking for is how far out of phase is the current compared to the voltage. please help me.

Alberto,
Thank you for your help, but I need a little more help. I tried to wire a Waveform Graph to the Phase Difference terminal on the Graph and Calculate Phase Difference (SubVI).vi. It seems as though the vi. is only collecting one point of data for output through the phase difference terminal. I need to be able to plot the phase difference between the two signals throughout the entire sampling time.
Please Help

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Acquiring multiple voltage and current sine waveforms, and log them along with the respective time stamp in a file."

"I am doing a data acquisition project using a 16 channel N.I. series 6020E card where I want to capture respective current and voltage sinusoidal signals. I am planning on capturing four pairs of matching current and voltage signals. I planned on taking one reading across the channels every fifteen minutes. This reading will need to be 60 data points per period or 3600 readings per second per channel in order for me to recreate the sine signal to determine the phase angle difference between the voltage and current. I was able to get one channel to capture a signal but could not get more than one working at a time. I am also trying to sycronize the data collection so all samples are with respect to each other. Thanks for any help."
-posted by cappy on 2/11/2002
John N on 2/12/2002 answered:
"Hi Cappy,
Could you post this question to the Hardware > Counter/Timer or Hardware > Multifunction I/O forums? I think you will get more responses there. Here is a link.
The hardware is usually a better differentiation since software can support such a huge range of functionality.
The data rates you are talking about sound reasonable. Are you using the USB or the AT interface?
One other thing to be aware of is that the samples taken will not be simultaneous due to the multiplexed nature of the MIO board measurements. However if you know the channel clock rate(output from one of the VI's), then you can calculate the time difference between each measurement and correct your phase measurements by that amount.
If you have more questions, please post this to the other forum and copy all of our discussion to let everyone know what we have talked about already.
Best Regards,
John Nieri
Applications Engineer
National Instruments"
I am using the USB connection. If anyone can help with or has a similar VI for this, it owuld be appreciated so I can work on the larger aspect of the total project.

The easiest VI to use for this acquisition is AI Acquire Waveforms in the data acquisition palette in LabVIEW. This VI allows you to perform a finite acquisition from multiple channels on your DAQ board. As John mentioned the acquisition from individual channels will not be truly simultaneous. There will be a slight time shift from one channel to the next on the order of the maximum acquisition speed of the card, 100kHz or 10 microseconds in your case. By accounting for this 10 microsecond delay between consecutive channels you can properly calculate the phase shift between voltage and current.
Christian L
NI Consulting Services
Christian Loew, CLA
Principal Systems Engineer, National Instruments
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Calculate symmetrical components of voltage and current

Hi, all. i am working on the calculation of symmetrical components of voltage and current in Labview. I have attached the relationship between symmetrical component and sequence voltage as picture 1. I will use this calculation for several times, so I wonder if anyone have some better ideas bc so far I just wired so many things together to realize the expression. It looks aweful. Any suggestion? such as built-in function to realize this function? thanks
Solved!
Go to Solution.
Attachments:
pic1.jpg ‏21 KB

Let's look at your formula (you don't say what's complex, etc., so modify as needed)
For example here's how you would create the A matrix from a given alpha.
Similarly, you can create the A^(-1) matrix (your definition of A and A^(-1) seem inconsistent, else you could just take the matrix inverse of A). After that, you can multiply with you V123 vector using AxB.
LabVIEW Champion . Do more with less code and in less time .
Attachments:
AlphaToA.png ‏7 KB

SCB 68 maximun voltage and current

Dear all,
can some 1 tell me whats the maximum voltage and current that my scb 68 for m-series is about the sense?i search the manual but i couldnt find.
cheers
Shawn

Hi!
   I know you're a little confused
   SCB doesn't have (perhaps I suppose...) electronic components, electronics is on the DAQ board! So you have to check for specifications of the board!
   A s I told you, from SCB specs you find that it can handle 250 Volt inputs, but your board, the board connected to the other end, on its analog inputs, supports from -11 Volt to + 11 Volt, referred to ground. This means that if you connect a 200 Volt signal to your board (through SCB, of course), you will likely damage the board, even if SCB will not be damaged. Is this clear?
   Carefully read specifications, there you can find many infos! Don't read just datasheets, search for device specifications, and user manuals.
   Anyway, in general, in a system, you should take the most stringent value as maximum rating, so consider this for further analysis.
   I've tryed to make it clear, i hope it is...
   have a nice day, now I'm going out for lunch (in Italy it's 12 o'clock)!
graziano

BK 9123A Voltage and current set problem

Hi,
I'm trying to use BK Precision 9123A power supply with Labview. I'm receiving error in the set operation of voltage and current. The error is attached. I've also tried other versions of the driver(2010,2009,8.2.1,7.1) but the error is the same.
The other operation, except for the voltage and current set, comes with the driver work good.
Thanks,
Attachments:
BK Precision 9123A Error.JPG ‏22 KB
BK Precision 91xx Series Monitor Output.vi ‏24 KB

Hi,
I am assuming you are setting the range, and the serial settings are correct.
Have you loked up the error code 50, this might give a clue on the error. Is the error coming directly after the "take measurement"?
Mark Ramsdale

I want to know hardware to collect voltage and current from battery and read it through labview

Hi all ,
As per requirement of my job I want to measure voltage and current of battery connected to motor. I want to read those voltage and current through Labview. I want to know what hardware I need to acquire that voltage and current and feed it to computer and read through Labview.
I also want to know, whether I need to program according to hardware I use or Whatever I will program will read data coming from hardfwarwe?
Please give suggestions over it .
Thanks
c59409

c54909,
It depends on what equipment you have available and what is your budget. You could for example use a storage oscilloscope with a current probe to accomplish this task. This will give you very good timing waveforms if your charging sequences are short.
If you are looking to automate I would recommend using any GPIB controllable power supply by Agilent or HP such as a (Agilent E3634A) and a USB-HS from National Instruments.
Keep in mind depending on how accurate you want your data you may need a GPIB current meter to read low currents in the uA. If you only need mA resolution you can usually use the same power supply you are making the voltage reading from. You want to make sure you pay attention to things like current limits on your supply and Over Current Protection settings (OCP) as they can make testing interesting.
Regards,
-SS

Recording measured voltage and current values from LCR 4284A

Hello,
I want to use the labview VI to record the measured voltage and current values from LCR 4284A. These are shown as Vm and Im on the instrument screen. Is it possible to record these values using a VI?
I have looked through the drivers that are available through the "Instrument driver network" (Link) for 4284A but none of the VIs give any option to monitor Vm and Im. If you know how this can be done then I would really appreciate a reply.
Thanks
Mansoor

I haven't used the instrument but there are functions to enable/read voltage level and current level monitors. Are those different than what you are asking for? What does the manual say about Vm and Im and programatically getting them? If you can find the command in the manual, you can just open the VI Tree and do a text search for the command.

After installing lion, my computer switches constantly between dashboard and current screen

I installed lion this morning and my screen switches rapidly between the dashboard and current screen, initially i thought it was my mouse, but after changing mouse I still get this issue and when my computer has been out of use for a while, i have to "erase" the screen to get to my login, any ideas?

After restarting your computer, try booting into the "recovery HD" by holding down Option at startup and try re-installing Lion. I had the Same problem when I installed Lion but that fixed it.
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Hub NH1005 vers 2 Need power cube voltage and current requirements

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Bob-r

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Need help getting a voltage and current reading with myDAQ

I have set up a VI using the DAQ assistant with the myDAQ, I am using the ai0 port for a voltage reading and using the DMM for my current reading, the circuit is working as I am measuring the voltage on a resistor after the ammeter but I am unable to get a current reading in order for it to work. If I have something wired wrong please let me know, thank you. My circuit is a 12VAC power supply, going through a potentiometer to drop the voltage to 8VAC, which passes through a resistor, ammeter is in series after this and attached to another resistor to complete my loop, the AI0 for my volt meter is connected across the second resistor, I have the proper voltage reading when I run the VI, but am unable to get a current reading to display. Thanks for the help.
Attachments:
Mikes Project2.vi ‏134 KB

I mean I can't get a proper current reading as a numeric value, I have my power supply going to a potentiometer to change my voltage level and then have 2 resistors, I am measuring the current between the 2 resistors. By doing so I am getting a value but not the same value I am getting on my multimeter, I am also having trouble with the calculation using the formula R=V/I in my formula node. If I use input controls I can get the formula to work properly, as soon as I connect it to the outputs of what I am trying to read, the formula node doesn't work.

How to use scb 68(pci 6221) for voltage and current measurement

hi

PCI 6221 is DAQ card with 68 terminals and SCB (Shielded Connector Board) 68 is termination board to those 68 pins of 6221 card, so that you can connect signals (to be measured) to appropriate pin of PCI 6221. You might already aware of it.
Refer to the pin out of PCI 6221 to check which is the correct terminal, for voltage measurements.
You cannot measure current directly, instead use a resistor of known value (and appropriate current rating), let current (to be measured) flow through it and measure the voltage across that resistor.
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My project is to measure ac voltage and current using lab view.

Dear Sirs,
I have a project to measure ac Electrical parameters such as current, voltage, power factor etc. through data aquisitioin with labview. Can I do that ?? If yes then kindly help me with some opinions and ideas. I shall be highly thankful to you.
Muhammad Hanan Azam.
Student of University of Engineering and Technolgy, Lahore, Pakistan.
Solved!
Go to Solution.

Yes it is possible. This can be acheived through serial communication. Read about serial communication like VISA, VISA configure, VISA wite, VISA read etc.
Read about the serial communication of device with you are going to communicate i.e. some communication document etc.
Kudos are always welcome if you got solution to some extent.
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Csv file reading and voltage and current plotting with respect to time samples XY plotting

Hallo,
I've been struggling with reading a comma separated value (csv) file from another instrument (attached). I need to plot this data for analysis. I have 5 column of data with numbers of rows, the first three row is the information of the measurement. I want to read 4th row as string and rest of the row as numbers. I want to plot 2nd column (i1) with respect to TIMESTAMP; 4th column(u2) wrt TIMESTAMP. And finally plotting i1 (x-axis) vs.. u2 (y-axis) in labview. Could anyone help me.
In excel its so easy to plot but I don't know how its done in labview.
Attachments:
labview forum test.csv ‏30 KB
excel plot.jpg ‏88 KB

Start by opening the file. Then use the Read Text File function. You can right-click on it and configure it to read lines. First make it read 3 lines (this is your extra header data). Then make it read a single line. That will give you your channel names. Then read the rest of the file (disable the read by line and wire a -1 into the number of bytes to read). Then use the Spreadsheet String to Array function to give you your data.
I would recommend going through the LabVIEW tutorials if you are really new at this.
LabVIEW Basics
LabVIEW 101
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TM2T * What are the voltage and current requirements of the Tm2T?

I didn't purchase the car adapter when I ordered my tm2t and it hasn't arrived yet so I can't check the power brick myself.
Are there car adapter sources other than HP?
Thanks

I bought this adapter from Meritline.com on sale for $15: http://www.meritline.com/merax-universal-portable-laptop-car-power-supply---p-39133.aspx
It works fine for my tm2t. I run it at 18 V, even though the adapter that came with my notebook outputs 18.5.
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3 licences purchased... no conectivity between licences and current catalouge... HELP!

Our office recently purchased 3 licenses of Lightroom 2 so that we can use it as a company asset management software for our photo library. We have 3 staff that will need to have access to the same catalogue to make imports and changes to our assets.
When we called Adobe to inquire about if the changes made by the 3 staff would be reflected in that catalogue we were told that it would be captured. We have the photos on a network accessible to all, have downloaded the software on two desktops, and my desktop has it accessible to me, but my colleague doesn't have access to the catalogue on her terminal.
I spoke to Adobe technical support, and they are indicating that the interconnection will not be possible unless the catalogue is copied into her terminal, and that not changes I make will be reflected in her catalogue and visa versa. This was the whole reason we purchased this software... I have been on hold with Adobe for 40 minutes... anyone have any suggestions or information to help me? I'd really appreciate the assistance!
Kristin

Unfortunately you're stuck. Lightroom is really only a single user product and catalogs cannot be on network disks without major hackery. So if you want to use it in your setting, you'll have to hack your way around it. You would have been better off using Bridge ( which would work great in this limited scenario) or a product geared towards digital asset management (Cumulus and the like). It's bad that Adobe initially told you it would work as this is well known to not be a feature.
That said, there are ways you can make this work part ways without copying the catalog all the time and without moving to another product. You can enable the writing of metadata to files. Either you do this automatically or manually (Save metadata to file in the metadata menu). What will happen is that Lightroom will write xmp files next to (or into if they are dng, tiff, psd or jpeg) the selected originals or every time you make a change (if you have automatic writing enabled). You can make the other copy of Lightroom then read in those files (Read metadata from file) and all changes to development and other metadata will carry over. If you have automatic writing enabled, I think Lightroom will throw up a warning or put a little badge on the file to warn you that the metadata on disk is different from the catalog, so that you can read it from the files.
There are caveats here which are all related to the standard parallel working problems. If you both work on the same file at the same time, one of the sets of changes will be lost in the end.

Phase Relationsh​ip between voltage and Current

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Phase Relationship between voltage and Current