Where to get small current transducers .. ?

Comments

• Timothy D. Swieter Posts: 1,613

  2009-04-28 00:32 edited 2009-04-28 00:32

  Franklin, what current rating are you interested in?
  
  I asked a similar question a couple weeks ago in the Sandbox thread (http://forums.parallax.com/showthread.php?p=795321. I did some looking around and I found a company in China that I will be placing an order with to sell the items through Brilldea. I won't be stocking items until the end of May I think, when I return from travel. Current Transformers seems to be a hot topic of several people's mind, so I am getting some for a system I am building and hopefully in time be able to help others like you by supplying them through my site.
  
  I will probably get a 15 amp or 20 amp version as well as something higher like 75 amp or 100 amp.
  
  p.s. The ones I found are like the ones you pictures, but a different color.
  
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  Timothy D. Swieter, E.I.
  www.brilldea.com - Prop Blade, LED Painter, RGB LEDs, 3.0" LCD Composite video display, eProto for SunSPOT
  www.tdswieter.com
• Franklin Posts: 4,747

  2009-04-28 01:08 edited 2009-04-28 01:08

  Thanks Timothy,For now I'm thinking the branch circuits are 15 or 20 amp and the main panel is 220v 200a (probably more than I want to deal with now) I'd like to see what you come up with.
  
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  - Stephen
• Timothy D. Swieter Posts: 1,613

  2009-04-28 01:33 edited 2009-04-28 01:33

  For CT (current transformers) I was going to at least monitor my main voltage feed into my house/condo/apartment in Singapore (I don't have the place picked out yet). The CT would run into an ADC that is controlled by the Prop. The Prop would be connected to the Internet for data logging on a web server. The CTs I hope to buy in a couple weeks when I return to HK. buying 15 amp, 20 amp at no brainers for me. I don't have a good feel yet for hte incoming power size. Maybe i need to e-mails some friends and ask what their incoming power feeds are know if I should get 100 amp, 150 amp or 200 amp CTs for that. In time I can stock more sizes if the product sells well, but at first I want to only buy a selected few.
  
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  Timothy D. Swieter, E.I.
  www.brilldea.com - Prop Blade, LED Painter, RGB LEDs, 3.0" LCD Composite video display, eProto for SunSPOT
  www.tdswieter.com
• yarisboy Posts: 245

  2009-07-13 02:50 edited 2009-07-13 02:50

  Check with suppliers of CTs for factory automation applications. At work all the major equipment has them. A ferrite ring with a toridal winding is installed around the line and an A-to-D converter will interface serially to your uP. Some have a diode and drive an LED indicator directly to show current draw like a pilot lite. Most residences are under 200 amp draw. The CT remote for my Fluke is a 1000:1 transformer so 200 amps reads out as 200 mAmps. When the meter at hand didn't have an AC current option I've driven a 10 ohm resister with the CT and read my current on the milli-volts scale.
  
  Post Edited (yarisboy) : 7/13/2009 2:55:52 AM GMT
• Timothy D. Swieter Posts: 1,613

  2009-07-13 03:14 edited 2009-07-13 03:14

  I have stock of some of the current sensors like the one pictured in the image above. I have 20A, 60A as well as the 100A version. The 100A version requires the resistor divider to be added, where the 20A and 60A version have them built-in. I don't have a page up on Brilldea yet, so feel free to PM or e-mail me for further details.
  
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  Timothy D. Swieter, E.I.
  www.brilldea.com - Prop Blade, LED Painter, RGB LEDs, 3.0" LCD Composite video display, eProto for SunSPOT
  www.tdswieter.com
• Timothy D. Swieter Posts: 1,613

  2009-07-13 10:56 edited 2009-07-13 10:56

  I have another thread where I talk a little bit about the current sensor, you can check it out here: http://forums.parallax.com/showthread.php?p=795321
  
  The data sheet is in the thread link above ( I tried attaching it here and I am getting errors). The clamps are blue colored plastic with a gray cable. I have stock of the 20A, 60A and 100A version. I don't have a website yet for the device, so you will have to send a PM to me with your e-mail address so I can forward a PayPal invoice. Each device is US$11.95. There is a flat rate of US$4.00 per order for shipping. The orders ship from Singapore via first class mail. We can ship the items faster if you want, but it is more costly.
  
  There hasn't been much time for me to try out the devices, so I can't offer many tips on usage - although as you can see in other threads there is plenty of help here.
  
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  Timothy D. Swieter, E.I.
  www.brilldea.com - Prop Blade, LED Painter, RGB LEDs, 3.0" LCD Composite video display, eProto for SunSPOT
  www.tdswieter.com
• CounterRotatingProps Posts: 1,132

  2009-07-18 21:21 edited 2009-07-18 21:21

  Hi Franklin and Timothy,
  
  this reminds me that I hadn't contacted you, Timothy, about these as I had mentioned in the other thread... just want to follow up. Franklin, this probably won't be of much help, but it's related enough that I thought to mention it.
  
  Though I've need for a couple of the 20's and may be two of the 100's also, I'm interested in better understanding power calcs using CT's. Parallax recently posted Beau Schwabe's COIL_demo.spin as the 'obex object of the week'. The code is actually distributed in the prop tool library. The demo is a nice learning tool for coils. Got me thinking and goofying around with homebrew CT coils, an op-amp, and a hack version of the coil demo prog.
  
  Once (if [noparse]:)[/noparse] I get it to work, I'll post the results. Sure, it would be more time-effective to purchase the CT coils, but the overwhelming DYI motive is usually illogical [noparse]:)[/noparse])
  
  cheers,
  Howard
  
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