Integrated Drive Generators (IDGs) or Variable Speed Constant Frequency (VSCF) generators mounted on each engine provide the main electrical supply.
If you are interested, I can provide more details on specific systems like hydraulic or pneumatic systems. Summary of Key Content Detailed study of 14 CFR Part 25 aircraft systems. transport category aircraft systems jeppesen pdf
Before diving into specific systems, it is essential to understand how aviation authorities categorize these aircraft. Under Title 14 of the Code of Federal Regulations (14 CFR) Part 25 (and its international equivalents like EASA CS-25), a transport category aircraft generally meets the following criteria: transport category aircraft systems jeppesen pdf