Found inside the base of the turret are capacitors, protected Aether Generators, and cooling systems, like a whole secondary engineering compartment. The Ke-B3-W3100 has systems separate from the rest of the ship (although they are designed to be connected to the ship's systems if needed) so that even if the battleship is disabled in combat, the guns can keep firing.
The turret dome contains the actual weapon itself. The turrets can be stored inside the top of their bases when not in use.
A Ke-B3-W3100 Superheavy Turret equivalent in firepower to the main cannon of starships like the Plumeria-class (2D) Medium Gunship.
See Damage Rating (Version 3) for an explanation of the damage system.