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Wind Generator Wattage monitoring


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12 replies to this topic

#1 Seyiwmz

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Posted 22 December 2008 - 03:15 PM

Hey Guys, I'd like to be able stream and log data about the watt production from my wind generator into my PC. Does anybody know what items I'd have to buy to make this work out. I was thinking the U3 and some external sensor would work, but never did anything like this before. I was hoping somebody had some experience doing this and had some ideas of what to buy. Thanks in advance. guy t. from michigan

#2 LabJack Support

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Posted 23 December 2008 - 07:49 AM

What is the max voltage and current? If AC, are voltage and current nice sine waves with no phase difference, or not?

#3 Seyiwmz

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Posted 24 December 2008 - 03:22 AM

This Generator is Grid Tied and produces 240 volt, with a peak output of about 15 or 17 amps. I believe we get nice sine wave output since we are tied to the grid and produce in frequency with the grid. I don't think there is any phase difference. Thanks for the response.

#4 LabJack Support

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Posted 26 December 2008 - 09:25 AM

The simplest solution I can think of is to just assume the voltage, and use a clamp-on current probe to measure the current. We have used the ESI-695 before:

http://www.amazon.co...duct/B000I17RAM

That clamp-on probe just outputs a DC voltage related to the RMS current, so is very easy to use.

Here is a topic about inexpensive current monitoring:

https://forums.labja...?showtopic=4261



Here is some related information from a support email:

Ohiosemitronics.com has various transducers. The AVT-150 series
(0-150 single phase AC input) is $98 for 0-5 or 0-10 VDC output. The
AVTR series adds true RMS and starts at $258:

https://www.ohiosemi...om/shopping.asp


Yokogawa has AC voltage or current transducers for $75:

http://www.yokogawa-...ower_trans.html

Only useful output option is 4-20 mA, so connecting to the LabJack
will require a resistor or LJTick-CurrentShunt. See current
measurement in the analog input section of user's guide.



#5 leibnitz

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Posted 04 January 2009 - 10:13 PM

If you enjoy your electronics and are ok to experiment a bit, there are some good miniature hall-effect current transducers available that can help with separating your low-voltage sensing (for safety) from the high voltage generated and mains output.

The hall effect sensors eliminate the need for a current shunt since an insulated wire can be passed through the bead without wiring the mains anywhere near your Labjack. They work like the current clamp meter noted above except if it is going to be used permanently then using a hall-effect sensor can allow you to recover your expensive clamp meter! The sensor output (5V, 0V and sensor output pin) can be simply adapted to the Labjack analogue inputs (the HV inputs are probably the simplest to connect without external op-amp, but you could use an op-amp and null-offset adjustment to adapt to the LV analogue inputs just as easy if you are ok with an op-amp circuit). Hall effect sensors like these may also be used for DC currents as easily as AC currents. These sensors can be readily applied to a whole lot of Labjack projects where current sensing is required. If you want to thread a few of them on the same wire, then you can have component redundancy and use the average value from two or three. If you have already bought a clamp on current meter then that could help you to calibrate your current measurements via the Labjack.

Examples of excellent low-cost mail-order hall-effect sensors for current measurement can be found at; http://www.raztec.co.nz/Products.html
The typical cost is around USD3.5 per unit (might vary by a few cents depending on model, qty and shipping dest) and the guys there are friendly, helpful and can ship within a few days.

You may also wish to excercise extreme care with mains voltages - even when you generator is stationary if the generator output remains connected to your distribution board then naturally it could kill you (or your buddy, or his mate) faster than blinking.
I hope this helps.
Regards, Jon

#6 Seyiwmz

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Posted 16 January 2009 - 12:45 AM

Thanks Jon, That's the set-up I ended up using. I've been testing and learning the software for the labjack on the bench. It works but I have experienced inconsistent readings. The CT I'm using needs a 6-12 volt excitation. I've tried 3 different wall transformers. A 5, 6 and 9 volt. I'm wondering if the wall transformers don't provide a clean enough DC to work properly. Some more expirements are to follow. Thanks for the reponse. Guy T

#7 LabJack Support

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Posted 16 January 2009 - 10:06 AM

What exact CT are you using? How do you have it connected to the U3? Are are you acquiring and processing the data?

Also see the following topic:

https://forums.labja...?showtopic=4274

#8 Seyiwmz

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Posted 18 January 2009 - 02:30 AM

Support, The hall effect sensor I chose to use is the CSLA2CD made by Honeywell found at many distributors like Digikey for $18.00. For every amp of current flow detected there is supposed to be .033 increase/decrease of voltage movement. So far, when I test by sending around 10 amps of flow I get different results. Sometimes I get a decrease and then the next time I get a increase. I ordered a regulated power supply, thinking that the supply isn't linear like it needs to be. Crossing my fingers in Michigan,,,,,Guy T

#9 LabJack Support

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Posted 19 January 2009 - 03:57 PM

One suggestion would be to pick a sensor that runs off 5 volts, which you can get from the U3. Topic 4274 mentions the Tamura L01Z series. You mean 10A RMS? Thus you have a current sine going from about -14 to +14 amps. If you are powering the sensor from 9 volts, your output signal would be a sine wave with a max of about 5 volts and a min of about 4 volts. How do you connect this to the U3, how do you collect the waveform (stream mode?), and what math do you do in software (RMS calc?)?

#10 Seyiwmz

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Posted 30 January 2009 - 11:26 AM

One suggestion would be to pick a sensor that runs off 5 volts, which you can get from the U3. Topic 4274 mentions the Tamura L01Z series.

You mean 10A RMS? Thus you have a current sine going from about -14 to +14 amps. If you are powering the sensor from 9 volts, your output signal would be a sine wave with a max of about 5 volts and a min of about 4 volts. How do you connect this to the U3, how do you collect the waveform (stream mode?), and what math do you do in software (RMS calc?)?




Hi guys, I ordered the LO1Z by Tamura. I hooked it up but did not put the 10k resistor onto the signal line. Hoping it would work without it. I tested using the same methods as before and got the same wacky results. It would work at first, then I would stop current flow and restart. Then, it would show a negative current flow. And each test would produce different results. Is it because of the missing resistor. And I'm not using stream mode. I'm just collecting the voltage from the sensor as an input. I use a formula in the conversion area to produce a graph that should represent approximate current. Any thoughts on why my results are so wacky.. Thanks guys, your the best.

#11 LabJack Support

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Posted 30 January 2009 - 08:40 PM

It does show a 10k resistor, so I would use one. Maybe the device actually outputs current and needs the resistor to create a voltage? I am not sure. I still don't understand how you are collecting the data. This sensor will output a sine wave. If you just grab a single point it could be anywhere on that sine wave, which sounds like what you are seeing. You need to collect the waveform.

#12 Seyiwmz

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Posted 31 January 2009 - 05:17 AM

Thanks for your reply, I guess I'm not collecting the waveform. All I'm doing is wiring the signal line from the sensor to an input. I don't know how to collect the waveform. Does that mean to use streaming mode? Thanks again. Guy

#13 LabJack Support

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Posted 02 February 2009 - 05:02 PM

Most likely you need to stream to collect data fast enough to get a waveform. See Sections 3.1 and 3.2 of the U3 User's Guide. What are you using for software? For testing, try using LJstreamUD from the U3 downloads page.


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