Alastair, I have a 370 page paper manual describing the electrical system of the 747-400.. and it still only scratches the surface!
This is probably too much to ask of the ladies and gentlemen here
Some Microsoft Flight Sim add-on's may have free manuals which help explain the system (I
think PMDG has one).
Of course, you need to know about basic electrics, otherwise the expressions used in these manuals will be meaningless (i.e. know what generators, inverters, transformers, rectifiers, busses, etc, are).
Rgds
NSEU