Hi all,
CTR tank cannot be used for takeoff simply because fuel coming from WING TKS is partially used to cool IDG's down, then it flows back to the wing tank having the cycle repeated. If we were to use CTR TK during takeoff (inhibited by CONF 1 slats/flaps selection), having both the wing tanks full, the fuel flowing back from IDG's would find no place to be "restored" into the respective wing tank ... So Airbus logic in this phase, automatically inhibits CTR TK and allows WNG TKS to automatically run in order to let place for IDG's fuel.
This automatic process planned by Airbus engineers does not allow us to use CTR TK because it would be automatically excluded again !
That's what I think,
captain87