While looking at the 747-400 electrical panel I see that the AC buses are paralleled. In this case there is a bus called a Tie Bus that serves as the connection point for the four engine generators and the two APU generators and the two external power sources. The sychronization of the AC buses must be automatic (it was manual in the 727 - what a pain). Each engine's main bus is connected to the Tie Bus by an Isolation Switch, which can be used to protect the Tie Bus from a bad supplier.
I assume the APU and external sources have an internal logic that prevents them all from simultaneously powering the Tie Bus, but I don't know what the logic is. I vaguely remember the 757 and 767 having the same setup, but I'm getting too old to remember such things. Here's a link to my scan of the 747-400 electrical panel layout: http://home.attbi.com/~davidculp2/747_elec.jpg Dave Culp _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
