In article ,
"Michael A. Terrell" wrote:

Think about it: When the output voltage matches the input voltage,
the transformer isn't even used. It is simply an unloaded transformer
primary connected to the AC line voltage. At any other voltage, the
current is determined by wire size. If the Variac is configured to put
out more than the line voltage, you have the same limit at the highest
voltage as you do at the midpoint.

Wrong, think again, at the midpoint the wiper is feed by two "wires"
carrying equal currents, while when set to boost the voltage, only a
single wire is feeding the wiper, so the current capacity at the
midpoint is twice the current capacity in the boost position.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/