I have a few variable autotransformers of unknown quality. What checks and/or tests should be performed to ensure that they are (safely) suitable for use? Can you recommend any URLs that I can study?
Thanks,
Bob
Suitable for use with what? A visual inspection and connecting one to power and measuring the output is about all I've ever done to check them, they're pretty simple devices, not much to go wrong really.
I have seen autotransformers designed for 400 Hz on the surplus market. They will draw excessive no-load current if powered up at 60 Hz ... unless you derate the input voltage by 60/400 = 0.15, which makes them rather useless.
Hopefully, yours have nameplates indicating ratings.
Roby
If you can visually inspect the windings, that's a good thing to do. I have run across a couple in which one or two of the turns developed some slack - who knows how? The slider tends to catch on the slack turn, which will probably make some fine fireworks if it drags the loop or breaks it.
Bill Jeffrey ==========================
James Sweet wrote:
Slap a load on them. Add a regular light bulb. Otherwise check ground and insulation.
N
That's easy enough to test for. Put a 150 watt lamp in series with the primary and power it up with no load. If the lamp lights brightly the transformer is either bad or built for a higher line frequency.
-- Former professional electron wrangler. Michael A. Terrell Central Florida
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