Re: gEDA-user: Transformer as voltage transducer?

[Peter Clifton <pcjc2@cam.ac.uk>]

On Sun, 2007-05-27 at 08:02 -0400, Randall Nortman wrote:
> So now I have to figure out if I really care about those >60Hz spikes,
> dips, and noise.  I am thinking not, so transformers should be just
> fine.  Then again, the reference designs for these Analog Devices
> chips just put a resistor divider between hot and neutral and feed it
> straight in without isolation.  They use neutral as DC circuit ground
> and derive power from the hot line, so the whole circuit is tied to
> mains without isolation.  If I did that, I would of course have to
> make sure that the digital interface between my measurement system and
> the PC that captures the data is isolated, which is pretty easy.  Any
> thoughts on that setup?

Not a bad setup, but like you say, needs careful attention to isolation
and insulation at appropriate points.

Be careful with resistors, they have a voltage rating, so for mains work
you may need more than one in series (in the high side of the divider)
to avoid them failing open-circuit.

Regards,

Peter Clifton




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