I'd like to build a low-accuracy ( 2% or so ) mains voltage/amperage/power measuring device.
Maybe single-phase, maybe 3-phase.
that seems to require purchasing small ( 5A in, 20mA out ) CT transformers.
similar to TZ76V or TZ76L at:
Problem is they have large MOQ.
Does anyone know of a source for such things in 100-off qty?
David
It depends. If you're happy with a sealed box, resistors work just fine. Actually, thinking about it, I suppose not so well for 3 phase.
It may not be necessary to use CT's if you use a dedicated power measurement IC such as Analog Devices ADE7756AN
A project describing a single phase power meter was described in Silicon Chip in July/August 2004
Since you appear to be in the UK this kit would work there since we use a similar power supply (we use 240Vac 50Hz MEN). You will only need to change the appliance output socket to suit the UK plug type.
A kit comprising all necessary components including a pre-programmed PIC is available from Australia for AUD 110.00 (UKP45.50). Even with postage you won't build one cheaper.
-- Triad CSE187-L From Digi-Key: http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=28853&Row=49334&Site=US
Ross, are you aware you posted this with "do-not-archive" - which means the record of this thread will be damaged?
--
Thanks,
- Win
I thought the opto-isolator mutiplier used in this was rather clever.
This optocoupler won't give you any accuracy. There are couplers intended for linear operation with a double output, one of which could be used for linearisation, but a small current transformer will be cheaper and more stable probably.
-- ciao Ban Apricale, Italy
I found this link that explains how to test the active power manually.
Its a straight forward test, I think accuracy will depending on the voltmeters and the series resisitor value.
Harshana
David Collier wrote:
voltage measuring device :
Does anyone happen to have a copy of Woodward's original article pp.102-103 of the October 14, 1994 Electronic Design?
Best regards, Spehro Pefhany
-- "it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
"mires" a écrit dans le message de news: snipped-for-privacy@z34g2000cwc.googlegroups.com...
Not wierdless, hopeless.
-- Thanks, Fred.
SNIP
Win,
I turned it off at a time when I was engaging in a verbal tet-a-tete argument with another poster some time back. I figured that any self respecting archive didn't need all the sh.t one sees in posts such as this. I also figured that if other posters not using X-no archive were interested in what I was posting on a particular subject, and which they thought deserved being archived, then they would do as you have done and included my words of wisdom in a response so that it did become archived.
I have now turned it back on again anyway...
Well I'm happy to pot this section, if it works for me.
I suppose I could use a 0R01 1/W resistor and some big tracks.
If it's that easy, why doesn't everyone do it that way? Presence of mains voltages on the PCB I suppose.
David
my hero. Thanks - I looked in DigiKey, but obviously looked straight past it.
1:500 wasn't quite the spec I wanted, but it is real, and off-the-shelf.David
Basically, yes. And that you've got to make sure all buttons/... are isolated. And that it can make it a bit more difficult to develop, if it's not isolated.
I think I've seen it Web somewhere Speff, or something extremely similar.... full circuit description, etc.
-- Tony Williams.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.