From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists.gentoo.org ([140.105.134.102] helo=robin.gentoo.org) by nuthatch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1G8vY2-0008WN-Db for garchives@archives.gentoo.org; Fri, 04 Aug 2006 09:00:50 +0000 Received: from robin.gentoo.org (localhost [127.0.0.1]) by robin.gentoo.org (8.13.7/8.13.6) with SMTP id k748vXb4025593; Fri, 4 Aug 2006 08:57:33 GMT Received: from smtp.gentoo.org (smtp.gentoo.org [140.211.166.183]) by robin.gentoo.org (8.13.7/8.13.6) with ESMTP id k748sj0t025324 for ; Fri, 4 Aug 2006 08:54:46 GMT Received: from localhost (localhost [127.0.0.1]) by smtp.gentoo.org (Postfix) with ESMTP id 2ADE4648C9 for ; Fri, 4 Aug 2006 08:54:45 +0000 (UTC) Received: from smtp.gentoo.org ([127.0.0.1]) by localhost (smtp.gentoo.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 00233-06 for ; Fri, 4 Aug 2006 08:54:37 +0000 (UTC) Received: from ciao.gmane.org (main.gmane.org [80.91.229.2]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.gentoo.org (Postfix) with ESMTP id 1DA1C645AE for ; Fri, 4 Aug 2006 08:54:36 +0000 (UTC) Received: from list by ciao.gmane.org with local (Exim 4.43) id 1G8vRy-000791-Fe for gentoo-user@gentoo.org; Fri, 04 Aug 2006 10:54:34 +0200 Received: from dhcp-83-219-111-81.customers.tvtnet.ch ([83.219.111.81]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 04 Aug 2006 10:54:34 +0200 Received: from remy.blank_asps by dhcp-83-219-111-81.customers.tvtnet.ch with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 04 Aug 2006 10:54:34 +0200 X-Injected-Via-Gmane: http://gmane.org/ To: gentoo-user@lists.gentoo.org From: Remy Blank Subject: [gentoo-user] Re: [Very OT] - Kill-A-Watt (240V Version) to measure my Gentoo Server Power Usage Date: Fri, 04 Aug 2006 10:54:24 +0200 Message-ID: References: <1154625941.27366.17.camel@neuromancer.home.net> <1154630731.27366.45.camel@neuromancer.home.net> <1154663408.7447.6.camel@orpheus> <1154663913.11070.12.camel@neuromancer.home.net> <1154670931.7447.65.camel@orpheus> Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@gentoo.org Reply-to: gentoo-user@lists.gentoo.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@sea.gmane.org X-Gmane-NNTP-Posting-Host: dhcp-83-219-111-81.customers.tvtnet.ch User-Agent: Thunderbird 1.5.0.5 (X11/20060802) In-Reply-To: <1154670931.7447.65.camel@orpheus> Sender: news X-Virus-Scanned: amavisd-new at gentoo.org X-Spam-Status: No, score=-2.59 required=5.5 tests=[AWL=0.009, BAYES_00=-2.599] X-Spam-Score: -2.59 X-Spam-Level: X-Archives-Salt: df12738c-525c-415d-8201-0d79fe3f860a X-Archives-Hash: ceea88ee31512e442f5e01a2d444c45e Iain Buchanan wrote: > um, I just came across a problem - it won't work with an AC power cord, > because you have active and neutral both going through the clamp in > opposite directions, hence they'll cancel each other out. You need only > the active going through the clamp... Or only the neutral. It doesn't matter, actually. > But "how it works" (with AC) is something like this: AC produces a > field around the wire as it "flows". This field in turn will induce a > current in a wire placed close to it. Loop a wire (transducer) around > another wire (AC current flow), and you can inference the change in > current in the original wire by measuring the current flow in the loop. > > It doesn't work with DC, as DC doesn't create a field (at least, not > when it's steady. When switching on and off a DC device, you'll still > get a change in current) > > IANAE(lectrician), so this might be complete bunkum, but that's how I > remember it anyway. You almost got it. Actually, it's not necessary that the current be AC: even a DC current produces a magnetic field around the conductor (albeit a DC field). The clamp is a ferromagnetic ring that "concentrates" the magnetic field, and it is interrupted at one location by a hall-effect sensor that measures the magnetic field. The current can be calculated from the magnetic field intensity and the diameter of the clamp ring. -- Remy Remove underscore and suffix in reply address for a timely response. -- gentoo-user@gentoo.org mailing list