help sizing toroidal PSU to stepper/drives

[paulus.v]

Yes, it's generally true and often much less in practice. But you do need enough bulk smoothing capacitance to cope with the occasional peak demand.

With my maximum of 24A (6 motors at 4A) should I go with 500VA or 630VA and what capacitance do I need for smoothing?

On the webpage of the toroid manufacturer the calculations are slightly different, and I'm a bit confused, probably I should ask them.

Full wave bridge (FWB) With capacitor:
VAC = 0.8 x ( VDC +2 )
IAC = 1.8 x IDC
WATTS = VDC x IDC (output)
VA = 1.4 x ( WATTS + 2 IDC* )