Confusion about transformer spec

Question

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.

Answer 1

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.

Answer 2

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.