sizing transformer for servo system ?

Hi All,

I am setting up a servo control system for a 3-axis mill using 90VDC
servos which are specified as 7.8A maximum continuous current and 38A
peak current.

On the transformers I am looking at, 2x38VAC seems to be a common
secondary configuration. Wired in series this is 76VAC and rectified
about 107 VDC minus two diode drops.

But what about the power rating ? I'm certainly not going to calculate
it for max peak current on all three motors (38*3=114A or 11kW!), but
should I size it for max continuous current on all three motors
simultaneously (3*8A= 24A or 2.4kW) ?

We do run 3D parts where all three axes would be moving simultaneously,
but the 3D toolpaths are finishing passes with low chip load. The heavy
cutting is done using the X/Y motors, and Z needs power when drilling...
so I'm thinking 2*8A or an 1.6kW transformer would be enough ??

thanks for any comments on this,

Anders