Also on that page it sais:
"If the RAT stalls or if the aircraft is on the ground with speed below 100 knots, the emergency generator has nothing to drive it. The emergency network transfers automatically to the batteries and the static inverter and the system automatically sheds the AC SHED ESS and DC SHED ESS buses."
THAT's the key to understanding the difference! The same happens in the air until the EMER GEN gets on line.
The main reason for this split into AC/DC ESS BUS and AC/DC ESS SHED BUS is to reduce the load on the batteries, as this condition is by AIs definiton only temporary (if reality knows about that may be another question).
Be aware: The system behaviour during RAT operation varies greatly depending on the age of the aircraft. Older aircraft 'lose' the RAT already below 140 knots (that means the entire final approach is on batteries only - so treat them nicely), while the newer rat stalls only at 100 knots during roll out.
Also on the older aircraft you'll have a CRM-Masterpiece in this case: Do you try to start the APU or not? If it works, you're back in business, if it doesn't, will your batteries last for the approach??!
During your training you will discover some more edges in the design which will leave you wondering who on earth designed and certified that, but that's the way it is. Look at the same feature on the A330/A340 and you'll be surprised...
Im A320 rated for 8 years after flying a nice, little, british 3-Engine-High-Wing for 4 years...
Good Luck, MAX
You may PM me anytime if confusion grows. And remember: It's not a bug, it's a feature
