Sensor for monitoring 3-phase power

[minnellac]

Does anyone have any experience using a sensor to track disturbances in 3-phase power. I'm looking for something to monitor up to 460VAC, and I'd rather not do all the signal conditioning and calculations across multiple channels myself. Something I can just poll through a serial connection would be nice. Any recommendations? I found this one: http://www.powertronics.com/store/pqroemmu.html, but I have no idea how nice it will be to communicate with.

Chris

[wd8ivl]

Chris,

This unit doesn't look like it will do what you want. The spec says it "stores the average once per minute". I would think that if you wanted to monitor power quality, you'd want to look at every cycle.

I found this one on the web:http://www.duncaninstr.com/pqr2020.htm but you have to email them to get more info...but from the connectors they show in the picture and the fact that they say "3-Phase", looks like it's capable of 480V.

Mike

[unclebump]

Here are a couple that I know about.

http://www.pwrm.com/

http://www.powerlogic.com/

[Henrik_Volkers]

Chris,

do you just want to monitor the voltage or the power?
If you want to monitor the power, you need to name the current too 😉
I use the TM39 from Zimmer Electronic www.zes.com
My one comes with a RS232 (Modbus) port and goes up to 30A. However you can use current and voltage transformer to extend the range.

[minnellac]

thanks for your input guys. I have a little more information now. It looks like the only goal is to monitor motor load. There are current transformers in place that step the current down 1000:1, so 1000A will be 1A from the CT. Conceivably, I could throw a resister in between the source and ground, and measure the voltage across it with a DAQ board. I am not really clear where I would go from there if I wanted to do this all manually (I'm still planning to recommend buying a box that does it, but I'd like to understand what's going on). I'd have to know the voltage in each line, and the phase relationship of all three lines. Would I then just sum the products of the respective currents and voltages at each instant? This would require 6ADC channels, and some significant conditioning.

As far as the black box search goes, I did get a quote on a system from Square D called the Enercept Basic (thanks Unclebump) that includes it's own CT's and provides Power as an output over RS232. It seems like this would fit the bill. I'm still waiting on responses from some of the other vendors mentioned.

I should fill in the blank on the specs for you guys: 3-phase, 460V, 10-1000A. Sorry I didn't include the current range the first time.

Thanks again.
Chris

[unclebump]

If all you want is a 0-10Vdc signal, this device is better and only around $500. It is from Load Controls Incorporated. The amp and voltage ranges can be changed with IC chips. They also have a version with an ethernet port. They also have a clamp-on portable unit.

[johnsold]

Ohio Semitronics makes a variety of power transducers. I have not used any of their equipment recently, so I cannot suggest specific models.

Lynn

[Conseils]

Your question on what is going on was completely missed and so I thought I would contribute.

I could have spent a considerable time remembering how to do all this and then I remembered a book that I wish had been arround when I was studying. I strongly recommend that you try reading it.

http://www.phptr.com/articles/article.asp?p=101617&seqNum=8

My recommendation would be that, at your apparent level of understanding you should limit yourself to working with an RS232 interface. See below.

However more importantly: -
You appear to be considering working with high voltage circuits and it is clear that you do not understand the principles and thus probably the risks and associated regulations apertaining to working on such systems.

It is most strongly advised that any work carried out on such systems is performed by a suitably qualified 'competent person'. It is normal for your local regulatory authority to insist on such a requirement for your health and safety as well as that of others!

[ossoo]

Hi Conseils,

I can not open the link.

I am very interested in the book. Could you tell me the name and author of the book?

Thanks

[RavensFan]

You need to copy and paste that.

Better yet, click this since this is set up as a link http://www.informit.com/articles/article.aspx?p=101617&seqNum=8