Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!philabs!seismo!hao!hplabs!sri-unix!towson@amsaa From: towson%amsaa@sri-unix.UUCP Newsgroups: net.micro.cpm Subject: Re: Transformers and European Current Message-ID: <13966@sri-arpa.UUCP> Date: Wed, 23-Nov-83 14:59:27 EST Article-I.D.: sri-arpa.13966 Posted: Wed Nov 23 14:59:27 1983 Date-Received: Sun, 27-Nov-83 04:50:47 EST Lines: 18 From: David Towson (CSD) David - The answer to your constant-voltage transformer question becomes self-evident as soon as you hear the other name for them: They are also known as "ferro-resonant transformers". Their operation depends on a tuned circuit whose resonant frequency is slightly off the operating frequency. As the line voltage input changes, the amount of core flux changes, and since the relationship of core flux to exciting current (which results from the applied voltage) is non-linear for iron-core inductors, the inductance of a choke (inductor) in series with the transformer part itself (it's all inside the box) changes and this changes the voltage actually applied to the trans- former. The thing is set up so that the change is in the right direction to adjust the voltage to near what it should be coming out of the unit. When you run it on 50 HZ, you totally mess up the resonant action, which is tuned for 60 HZ. And that's the rest of the story. Dave