If it has use in a modern world, there is a modern equivalent. But if you want to haul antique cast iron, it is up to you.
I like how people get all fussy about HRC fuses in a multimeter, yet have no problem using 70 year old equipment handling 600 A.
It is probably better saved as a museum piece.
Of course it has a use in a "modern world". Various companies still make the same kind of instrument today, for example, this cheap one available at places like PA/HF:
https://www.princessauto.com/en/detail/500a-battery-load-tester/A-p8494007ehttps://www.harborfreight.com/500-amp-carbon-pile-load-tester-91129.htmlThey are generally flimsy and poorly built, though. I would
much rather have that old Sun in his photo than that
modern Chinese one! It almost certainly works absolutely fine unless someone horribly overloaded it at some point.
If it was a reasonable price, I would have bought it, for sure and wouldn't hesitate to use it! It even has the voltmeter completely separate and the range is adjustable to 50V, which makes it a more versatile instrument.
What rheostat? All I see are two rotary switches.
It's not a
rheostat per se, rather an adjustable carbon pile. That big knob in the middle of the front adjusts the load.
When I bought my load tester, I decided to opt for one of the quick-testing digital ones with a fixed load and a microcontroller that samples the sense wire and does some calculations. In hindsignt, I wish I'd bought a standard analog-metered adjustable carbon pile. Much more versatile and still on my "buy one someday" wishlist.