[Boatanchors] Running European 230 VAC on our AC

[WA5CAB at cs.com]

Glen,

What he said was that what should have been the neutral connection for the 
autotransformer (the I/O common) was connected to Line, not Neutral.  Which 
put what should have been the Neutral connection for the internals at Line 
(120 RMS) instead of near ground.

Robert

In a message dated 10/21/2012 10:08:25 AM Central Daylight Time, 
gzook at yahoo.com writes: 
> The neutral is NOT 120 VAC above ground!  That assumes that one side of 
> the 240 VAC is grounded which is not the case in this country.  The 
> secondary on the "pole pig" (distribution transformer) is center tapped with 120 
> VAC on either side of the center tap.  The connection to this center tap is 
> the neutral.
> 
> At the entrance to the building, the connection to the neutral is grounded 
> by an external connection usually to a ground rod driven near the entrance 
> point.  This puts the neutral basically at "ground" potential.  In 
> 240-volt 3-wire systems (no longer approved for new installations) all 3-wires 
> coming from the pole pig continue to the load.  In 240-volt 4-wire systems 
> there is an additional "ground wire" which is connected to the point at which 
> the neutral connects to the external ground rod.
> 
> For the 120 VAC distributed within the building, one side of the 240 VAC 
> and the neutral are involved which gives 120 VAC.  Then, a ground wire is 
> added for safety.
>  
> Glen, K9STH
> 
> 
> Website:  http://k9sth.com
> 
> 
> ________________________________
> From: Sheldon Daitch <sdaitch at kuw.ibb.gov>
> To: 
> Cc: "boatanchors at mailman.qth.net" <boatanchors at mailman.qth.net> 
> Sent: Sunday, October 21, 2012 5:06 AM
> Subject: Re: [Boatanchors] Running European 230 VAC on our AC
> 
> As noted, some 240VAC US appliances do need the neutral
> to pick up the 120VAC for some 120VAC applications in the
> unit.
> 
> We have a US built stove which the manufacturer has to add a
> stepdown transformer for the export model, since the 230VAC
> systems outside the US typically do not have the neutral
> centertap.
> 
> In our stove, that stepdown transformer was an autotransfomer,
> not an isolation transformer and it failed.  I discovered that the
> way the transformer was wired and the stove was wired into
> our 230VAC system that the common of the autotransformer
> was wired to the high leg of the wiring and perhaps that was
> the cause of the eventual failure of the transformer.
> 
> I bring this up, as running  230VAC equipment which is designed
> for a hot and neutral might have some problems if the neutral
> leg is actually 120VAC above ground.  In theory, no, but with
> polarized systems, the powered unit is normally going to see
> near-ground voltage outside the US, but in the US, the neutral
> leg would be 120VAC above ground.
> 
> (One interesting aspect of many 230VAC systems outside the
> US is that many residential systems are three phase, and
> with 230VAC phase to neutral, phase to phase voltages are
> in the 400VAC range.)
> 

Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480