 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Windmills : Alegro Current Sensor shunt problem [SOLV
| Author | Message | ||||
FrancisGreaves Newbie  Joined: 07/04/2012 Location: IrelandPosts: 4 |
I was delighted to see the article on the Alegro current sensor on the home page. I am going to be using one to monitor my windmill (3m diameter 48v), which I have just got going, because I could not get Measuring DC current with an LT1495 working in any sort of stable fashion. I am using an Arduino for monitoring RPM, Volts and Amps. I followed the link to the Alegro article on shunts, and set about trying to calculate the size of shunt needed to scale my 20A ACS712 up to 30 or 40A. To my surprise, if you follow the worked example to calculate the Wshunt, the result I get in a spreadsheet, and on my calcualator is 0.0042839803mm Not about 3mm as they say. It took me a while, then I spotted it whilst writing this post! The Rprimary should be entered as 0.0015 Ohms, not 1.5 as in the worked example. I am going to use a bit of copper pipe which is 0.8mm thick to do the job. I thought by posting I might save someone some anguish. I have informed Alegro. Perfect in every way, Modest and Misunderstood! |
||||
| FrancisGreaves Newbie Joined: 07/04/2012 Location: IrelandPosts: 4 |
I know I am replying to myself, but since my post I have worked out the sizes of shunt needed to convert a 20Amp sensor into a 40 or 50 Amp sensor. A copper pipe is not the answer. It is far too thick. Using the formula provided by Alegro, I calculated the size of Wsens = 2mm, Wshunt = 3.1mm using a PCB board with copper Thickness = between 0.05mm and 0.08mm. Hope this may help someone. Perfect in every way, Modest and Misunderstood! |
||||
Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Thanks for that Francis. Another sensor worth looking at http://www.thebackshed.com/forum/forum_posts.asp?TID=4763&PN =1 Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
||||
 Print this page |
