Can I generate 240VAC by feeding 120VAC through a 1:1 isolation transformer to generate 120VAC that is 180-degrees out-of-phase with the mains, tying one end of the isolation transformer secondary to AC neutral (to ground reference it)? I should then have 120VAC with a 180-degree phase shift on the other end of the secondary and 240VAC between that end and the original AC hot wire. Is this OK?

 

Originally posted by dalbert@Jan 1 2006, 11:40 AM
Can I generate 240VAC by feeding 120VAC through a 1:1 isolation transformer to generate 120VAC that is 180-degrees out-of-phase with the mains, tying one end of the isolation transformer secondary to AC neutral (to ground reference it)? I should then have 120VAC with a 180-degree phase shift on the other end of the secondary and 240VAC between that end and the original AC hot wire. Is this OK?

[post=12827]Quoted post[/post]​

Yes, you can do it. Wire it up and connect a voltmeter between the two points where you expect to get 240 VAC. If you get closer to 0V than 240 V, then reverse the secondary wires and try again for 240 V.
What you propose is the same thing as an autotransformer once you put your wiring in place.

 

Note, the 240 volts will no longer be isolated from the input.