Hi Andy;
Some years ago the US code requires earth ground and common line to be
isolated. This prevents voltage drop in the common line jacking up voltage
on the equipment. The transformer will isolate the common return for you so
your equipment will stay at earth ground and you won't glow in the dark when
you touch it.
Hope this helps.
Don
On Tue, Sep 6, 2011 at 9:34 AM, andy pugh <bodge...@gmail.com> wrote:
> I have made a servo PSU. It simply rectifies mains voltage to give me 325V
> DC.
>
> https://picasaweb.google.com/lh/photo/HdNJXBD5wPqDUi9E8C46HQ?feat=directlink
>
> https://picasaweb.google.com/lh/photo/dTcU2i7GYh53xSrqjh--BQ?feat=directlink
> There is a bit of extra componentry in the box to discharge the caps
> on power-off and to switch in a resistor for soft start, but basically
> it is just a rectifier and some caps.
>
> I am a bit puzzled about the status of my -V.
> I guess that my 0V will be a few volts away from neutral, which is a
> few volts from earth. Should there be an explicit connection between
> my DC- and earth, machine 0V, mains neutral, none of the above?
>
> I think perhaps I should have a 1:1 transformer to float the DC, which
> would then allow such a connection.
>
> --
> atp
> "Torque wrenches are for the obedience of fools and the guidance of wise
> men"
>
>
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