Envelope-to: dave@picks.force9.co.uk Delivery-date: Sat, 17 Sep 2005 10:34:20 +0100 Received: by pih-mxcore11.plus.net with spam-scanned (PlusNet MXCore v2.00) id 1EGZ5P-0008A8-RX for dave@picks.force9.co.uk; Sat, 17 Sep 2005 10:34:20 +0100 Received: from post.thorcom.com ([193.82.116.20]) by pih-mxcore11.plus.net with esmtp (PlusNet MXCore v2.00) id 1EGZ5P-00089q-O2 for dave@picks.force9.co.uk; Sat, 17 Sep 2005 10:34:19 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1EGZ4j-0000ER-1q for rs_out_1@blacksheep.org; Sat, 17 Sep 2005 10:33:37 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1EGZ4i-0000EI-Kc for rsgb_lf_group@blacksheep.org; Sat, 17 Sep 2005 10:33:36 +0100 Received: from newbox.tcp.net.uk ([195.80.0.243]) by relay1.thorcom.net with esmtp (Exim 4.51) id 1EGZZB-0002JS-Lh for rsgb_lf_group@blacksheep.org; Sat, 17 Sep 2005 11:05:06 +0100 Received: from [212.248.140.34] ([212.248.140.34]) by newbox.tcp.net.uk (8.12.7/8.12.7) with ESMTP id j8H9YjIV010202 for ; Sat, 17 Sep 2005 10:34:50 +0100 (BST) Received: from 127.0.0.1 (AVG SMTP 7.0.344 [267.11.1]); Sat, 17 Sep 2005 10:33:44 +0100 Message-ID: <001601c5bb6a$e59c9960$045bfea9@d4f8d8> From: "Andy Talbot" To: rsgb_lf_group@blacksheep.org References: <000001c5b9f2$d48dbc90$e6a4c593@RD40002> Date: Sat, 17 Sep 2005 10:33:43 +0100 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Mime-Version: 1.0 X-TCP-MailScanner-Information: Please visit www.tcp.co.uk for more information X-TCP-MailScanner: Found to be clean X-TCP-MailScanner-From: actalbot@southsurf.com Subject: LF: : Current Transformers (off topic, but expertise probably here) Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=iso-8859-1; format=flowed X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-PN-SpamFiltered: by PlusNet MXCore (v2.00) Thanks for your responses to this. I reduced the burden resistor to 440 ohms (for 0.1V/A) and got adequate linearity (with only 1V across the 240V secondary ! ) and have now managed to capture the voltage and current waveforms needed for the analysis. It really was a nasty little transformer. Next time I need to monitor mains current waveform will go the optical isolator route instead. They can give quite good linearity if used with care and a bit of feedback. Andy G4JNT -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.11.1/104 - Release Date: 2005-09-16