X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from sj-iport-2.cisco.com ([171.71.176.71] verified) by logan.com (CommuniGate Pro SMTP 5.2.2) with ESMTPS id 2875869 for flyrotary@lancaironline.net; Mon, 28 Apr 2008 17:02:52 -0400 Received-SPF: softfail receiver=logan.com; client-ip=171.71.176.71; envelope-from=echristley@nc.rr.com Received: from sj-dkim-1.cisco.com ([171.71.179.21]) by sj-iport-2.cisco.com with ESMTP; 28 Apr 2008 14:02:08 -0700 Received: from sj-core-2.cisco.com (sj-core-2.cisco.com [171.71.177.254]) by sj-dkim-1.cisco.com (8.12.11/8.12.11) with ESMTP id m3SL28gI010628 for ; Mon, 28 Apr 2008 14:02:08 -0700 Received: from xbh-rtp-211.amer.cisco.com (xbh-rtp-211.cisco.com [64.102.31.102]) by sj-core-2.cisco.com (8.13.8/8.13.8) with ESMTP id m3SL28nc005779 for ; Mon, 28 Apr 2008 21:02:08 GMT Received: from xfe-rtp-202.amer.cisco.com ([64.102.31.21]) by xbh-rtp-211.amer.cisco.com with Microsoft SMTPSVC(6.0.3790.1830); Mon, 28 Apr 2008 17:02:07 -0400 Received: from [64.102.76.127] ([64.102.76.127]) by xfe-rtp-202.amer.cisco.com with Microsoft SMTPSVC(6.0.3790.1830); Mon, 28 Apr 2008 17:02:07 -0400 Message-ID: <48163B56.4010706@nc.rr.com> Date: Mon, 28 Apr 2008 17:02:14 -0400 From: Ernest Christley Reply-To: echristley@nc.rr.com User-Agent: Thunderbird 2.0.0.12 (X11/20080227) MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: the Kubota dynamo References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 28 Apr 2008 21:02:07.0797 (UTC) FILETIME=[1E7E0E50:01C8A973] Authentication-Results: sj-dkim-1; header.From=echristley@nc.rr.com; dkim=neutral SHIPCHIEF@aol.com wrote: > George (down under); > Could do that, we were just refering to how the regulator handles excess > power with a PM alternator, that is, it can't reduce the alt output, it can only > sink excess power to ground and let the excess heat go somewhere. > That's a strong motivator to size the alternator output to be no greater than > the desired load. > Scott E > That is one method for regulation. Take in everything and dump what isn't necessary into ground. The problem is that an over-rev will pump too many electrons through the stator wires and burn them up. A more modern method is to put a solid-state switch in the circuit. If the generator puts too much voltage out, cut the circuit then bring it back online when the regulator output drops. The regulator switches (hence the name "switching regulator") at a rate high enough that the regulator appears to be stabilized around the set voltage. The heat sink method is good enough when the engine rpm and loads are characterized well enough for the more sophisticated electronics to not be needed.