There was an article in Circuit Cellar (or maybe it was Nuts & Volts) a=20 few years back, using a Toroid with a few wraps of the 120volt load=20 wire, and a few wraps of an output wire, to either a diode, or rectifier=20 bridge as an analog input. Seemed to be a cheap way of monitoring a=20 circuit, plus the toroid is small, could easily fit numerous in a=20 confined main breaker panel. Sorry don't have any more info . On 1/19/13 3:17 PM, KPL wrote: > Thanks for a quick response, it's now clear. > > Device I'm thinking of does not need big precision, I just want to > measure kind of average current per period, to switch off some load > before circuit breaker trips. > > On Sat, Jan 19, 2013 at 9:20 PM, Sean Breheny wrote: >> Hi, >> >> No, it would not make a difference (or at least a very tiny one - it >> might change the coupling between the primary _leads_ and secondary >> _leads_ but it would not change the coupling between the primary and >> the secondary coils, and the coupling between the coils will be far, >> far larger and more dominant than the lead to lead coupling). >> >> For a toroidal transformer all that matters is the number of times >> that a wire passes through the middle (hole). >> >> The situation which is less clear is when you have a core that has >> more than one opening in it, like an E-I core in a transformer. In >> that case, fractional turns counts are possible depending on how the >> wire passes through the two openings. >> >> Sean >> >> >> On Sat, Jan 19, 2013 at 2:01 PM, KPL wrote: >>> Hi, >>> >>> I have ordered some current transformers, to measure average current >>> in AC line. >>> http://docs-europe.origin.electrocomponents.com/webdocs/0f47/0900766b80= f47965.pdf >>> >>> I know usually power wire is just run through the core, but would it >>> make any difference, if that wire made actually a full turn around the >>> core, with ends crossing outside, not running through it twice? >>> >>> -- >>> KPL >>> -- >>> http://www.piclist.com PIC/SX FAQ & list archive >>> View/change your membership options at >>> http://mailman.mit.edu/mailman/listinfo/piclist >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist > > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .