Electronics > Projects, Designs, and Technical Stuff
Testing back to back power transformers for use as an isolation transformer
intabits:
--- Quote from: soldar on May 11, 2019, 06:24:33 am ---
--- Quote from: intabits on May 10, 2019, 04:51:18 pm --- With the big ones, I could connect the 220V primaries in parallel to the mains, and their 120V secondaries in series.
--- End quote ---
That doubles the power they can handle. Back to back they can only handle the power of the smallest one but in parallel they add up.
Be careful about the secondaries in parallel having the same voltage. A volt or two will not really matter, especially under load, but if there is much difference you will get wasted heat.
I connect one end of the secondaries and measure voltage between the other two open ends. That way you also make sure they're in phase.
--- End quote ---
I was actually talking about the secondaries in series (each 120V) to get isolated 240V.
But should I ever need 120V at high power, I would be checking as you described.
Psi:
If you can find a dead UPS (which is usually very easy for a few $ or free) they are a good source of a single transformer with two mains windings.
(They have Mains in, Mains out and Battery windings).
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