From: John Woodgate
Subject: Re: Current Sensing Schematic
Date: Thu, 28 Nov 2002 18:57:50 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Thu, 28 Nov 2002 21:51:34 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Spehro Pefhany
wrote (in <firstname.lastname@example.org
om>) about 'Current Sensing Schematic', on Thu, 28 Nov 2002:
>On Thu, 28 Nov 2002 17:33:15 GMT, the renowned "Marc H.Popek"
>>Yes! Think about rogowski coil as the traditional solution to this problem.
What an extremely helpful response!
>Wouldn't get much output, would you, unless you separate the
>conductors of the line cord?
Not even then. Winding one wire round another does NOT produce a
transformer, which is what you need to construct. You need a toroidal
magnetic iron core. You wind about 100 turns around the core. Depending
on the current you want to measure, you may just be able to run ONE of
the load conductors through the hole in the middle, otherwise you need
to wind a few turns round the core. The you put a LOW value resistor
across the 100 turn winding, like 100 ohms, and measure the 60 Hz
voltage across it. That voltage is proportional to the load current. 1
volt corresponds to 1 A if you have just the load conductor threaded
through the central hole.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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