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From: jewett@hpl-opus.HP.COM (Bob Jewett)
Newsgroups: sci.electronics
Subject: Re: 100V Japanese products on 120V US lines
Message-ID: <65200007@hpl-opus.HP.COM>
Date: 2 Jan 90 17:20:21 GMT
References: <3215@uceng.UC.EDU>
Organization: HP Labs, High Speed Electronics Dept., Palo Alto, CA
Lines: 20

> Only a small quibble:  the *primary* current is what you have to worry
> about, not the secondary:  since all the load current flows through both
> transformer windings, ...

Nope.  The current ratio of secondary to primary is still about 5:1.  It is
easier to see if the schematic is redrawn:

				 24V secondary
  Hot,120VAC    0-------*----------wwwww------------0 Hot,~90V (or 150V!!)
                        |       ===========
                        *-------mmmmmmmmmmm-*
                              120V primary  |
                                            |
                                            |
 Neurtal,120VAC 0---------------------------*-------0 Neutral

The load current flows only in the secondary.  If you want to be safe, you
also have to worry about fuses and which side of the line is neutral.

Bob Jewett