"DoN. Nichols" wrote in message
...
On 2017-06-09, Jim Wilkins wrote:
"DoN. Nichols" wrote in message
...
On 2017-06-08,
wrote:

[ ... ]

I say "for house use" because there are also 240VAC industrial
versions, which have an additional (center) tap. You can feed in
120
VAC between one end and that center tap, and get up to 240 VAC
output
(at the cost of lots more current from the 120 VAC line than you
feed
out at 240 VAC, of course.

The Superior Electric "Powerstat" is pretty much the same,
including similar voltage taps.

The maximum output current decreases considerably as the brush
moves
above the line voltage. My 10A 120/240V Powerstat 236 is rated for
only 4A at 120V in, 240V out. Trying to pull more current loads it
down.

O.K. That makes sense. I've never had to deal with that
problem. And I don't have one on hand to read the current limits
from
the data on the terminal block.

Try this. It's too big for me to check with my limited dialup
bandwidth or monthly cellular data allocation.
http://lcweb2.loc.gov/master/mbrs/re...og%20P258G.pdf

From my download of the Powerstat catalog C7002-1:

"CONSTANT CURRENT LOAD: Output that can be carried regardless of
output voltage setting.

CONSTANT IMPEDANCE LOAD: loads such as incandescent lamps or
resistance heaters in which the current drawn is approximately
proportional to the applied voltage, increasing to maximum current at
line voltage. These ratings apply only to units having maximum output
voltage limited to line voltage."

Their tech support confirmed the catalog's 5A Const I, 7A Const Z
rating of a Type 21 whose nameplate gave 3.75A as the limit.

When I tested a type 10 at its 3.0A Const Z rating an IR thermometer
indicated the brush temperature as 100C. It was driving a 24VAC 250VA
control transformer with a rectifier / capacitor output. The
combination is well matched and makes a decent 10A variable power
supply and battery charger. It will provide 15A briefly, until the
Powerstat and transformer primary overheat.

I added the output capacitor to stabilize the readings of digital volt
and amp meters.
http://www.ebay.com/itm/DC-0-30V-0-1...#ht_1505wt_868

-jsw