Originally Posted by
Someone Somewhere
NGS and HYD L are in the lower right.
It looks like there isn't a dedicated NGS motor controller; instead it is powered from either the HYD L CMSC or the cabin air compressor R2 CMSC.
Running two motors simultaneously on the same variable-frequency drive is considered possible but not preferred in industry; I am not sure whether it's something Boeing does. I would be expecting to stop the motors, rearrange the contactors, then restart the motors.
Correct. The NGS pump is run by either of the 2 CMSCs on the R2 230 VAC bus. One of those usually runs the right outboard (R2) cabin air compressor and the other usually runs the left hydraulic system's electric motor pump. The outboard CACs aren't used on the ground. The R2 CAC also turns off during descent to allow the NGS to run.
Originally Posted by
NSEU
Yes, not sure. I found a table online of what system was on what branch of the electrical system, but the listings were L1 ~L8 and R1~R8. The NGS was on R4. I can't relate that to anything in the diagram or other diagrams I have.
Originally Posted by
TURIN
That sounds like a reference to the CCR.(Common Core Resource) basically the brains of the aircraft.
Both CCRs have eight individual processor modules (GPMs?) that can be referred to as L1 to L8 and R1 to R8.
Right. The NGS is controlled by the R4 General Processing Module of the Common Core System.