Be awarre that the electrical systems on the Classic and Next Gen are pretty different.
The the basics are always the same.
The primary sources of AC power are the (2) IDGs (Integrated Drive Generators) which are engine-driven and the APU Starter-Generator. There is also External Power.
In an emergency, Standby AC power can be supplied by a Static Inverter which changes DC to AC power.
The primary sources of DC power are the (3) Transfornmer Rectifers which rectify 115VAC (from the generators or External power) into 28VDC. The battery also supplies 28VDC.