My bet you have the inputs on the wrong points.

The 'Mains' go across the whole coil.
The white wire connected to one end of the coil is zero volts out the
wiper. When the wiper (the output) is turned to the other end it is at the max.

The variac should easily idle on the power supply at any wiper value when no
load is attached. The output is the wiper.

Martin
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Life; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/


Grant Erwin wrote:
I have a 20 amp variac. Yesterday I tried plugging it into a 20A circuit
with its output voltage set to 30% of input voltage, and it
(consistently) popped
the breaker. When I set it to 100% of output voltage, however, it didn't
pop
the breaker. Obviously the magnetizing current is higher with the variac
turned
down. The question is why? What's going on here?

I believe the variac and my electrical circuits are both in good working
condition, in other words I don't believe this is faulty behavior.

Grant Erwin
Kirkland, Washington

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