your top diagram is correct, for 230Vac applied to the LHS, you will have 360 Vac on the sec at 119VA, this will peak rectify to 504V, need lots of C on the rectifier to keep the volts up for light loads ( < 0.5 amps )
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Oh yes, you can add in the 5Vac from the bottom winding to get 510VDc or thereabouts at light load...
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for short term operation ( 50% duty say ) you can overload the Tx up to 2x 240VA as long as you have good o/p bridge rectifiers, 1kV 25A say, and decent caps on the DC 385 - 450VDC in series with balancing / bleed resistors, and 1000uF or larger to reduce ripple and keep the average volts up ...