On 02/03/2014 7:14 AM, wrote:
Thanks for your reply John. Yes the variac was isolated by means of an isolation transformer ahead of it. I essentially did what you mentioned. That is, I assumed that the DC output was placed in parallel with the AC train voltage, and did that from my DC bench supply. That's when I noticed the huge current draw on the DC supply. I was questioning if that was normal. Lenny.


In that case then the DC supply was essentially shorted out by the
secondary winding of the Variac.

I am pretty sure the only way this could work is as I described where
the AC/DC is switched back and forth with a DPDT switch - both voltages
can't be present at the same time.

John :-#)#

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