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I see transformer specs listed as 360-0-360 for a secondary of a power transformer. I understand that this means there is a center tap, and with a full wave rectifier this comes out to VRMS * 1.4142 = 360VAC * 1.4142 = ~509 VDC (assuming smoothing caps etc, beyond the scope here)

But if you remove that center tap, then you could say the transformer is 360-360, or 0-700, correct? So if you then used a full wave bridge rectifier on 720VAC, you would have 720VAC * 1.4142 = ~1018 VDC.

Obviously I'm missing something crucial here about how transformer specs are defined. I certainly don't want to be off by a factor of 2 when I'm getting my transformer manufactured.

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    \$\begingroup\$ You did calculate correctly, so what's the question? \$\endgroup\$ – Marko Buršič Jan 6 at 21:46
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It's a 720 VAC secondary, with a center tap it makes 360-0-360. You can get a 1018 VDC out, or by using the center tap as 0V, you get +509 and -509 VDC. Same thing.

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  • \$\begingroup\$ Are there any savings when using a transformer with a center tap? Since you physically have two 360 volt windings, is the duty cycle essentially halved for the windings, allowing for double the current, vs using a single 360 volt winding of identical gauge wire into a bridge rectifier? It seems like some sort of physical voltage/current tradeoff should exist here. \$\endgroup\$ – cat pants Jan 7 at 23:50
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The transformer specs are fine as are your calculations. If you use either half of the transformer secondary, you will get 509 VDC out of a rectifier/filter combination. If you use the full secondary (leaving the center-tap open), everything will double since you are using the entire transformer windings.

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