This one weighs 25 lbs and is rated for 1.5 KVA, 250 V and 6A. also no question about quality, it's American made and at *least* 60 years old.
I was discussing this with a friend the other day. We think it's a theatrical lighting unit. Obviously not safe to use without a proper enclosure and other enhancements.
I have a vintage Australian made/licensed version of that Powerstat above in an 8 amp rating at 240 volts and it will handle 10+ amps at 240 volts short term without issue or 'skip'
Quality windings with solid arm that makes excellent contact, with beefy precise cut carbon brushes that track perfectly,
good thick wiring and control wheel for fast or gradual voltage swings from 0 to 290,
housed in a strong metal framework
Probably 60 years old when I got it, and after a good dust off, TLC, capping off exposed terminals, a proper mounting base with handles and input/output gear,
this 1960s? beast is good for another 60 years
Tip:
when not in use, suggest to cover up the top of variacs so dust doesn't sneak in and settle on the top of the windings, acting like wet n dry sandpaper,
giving the carbon brushes more work than they need, hurdling over obstacles
Plastic shopping bags work for me, total wrap over, keeps the variac operating good as new every time, and TLC free
There is no way one of those red half baked MIC 'potentiometers' on steroids will see my credit card unsheathed, I've seen what's inside them,
it's -How OneHungLow can you go? quality all the way... or if you really have no choice, buy a 2kva model, de-rate, re-fuse and re-label it to 500va, cross your fingers, and don't leave it unattended in use
This is after opening it up to check and or correct any cheapassedness that will be there in 99% of cases.
Sometimes you can get lucky and score a well made unit with everything anchored down properly, probably due to one day in the OS working week that isn't a Friday
Reality humor aside, it's old school variacs for me that kick ass, no matter what they cost, weigh or fugly they are
Same deal with isolation transformers, no cutting corners where electrical manipulation is called for