@BobbyD is correct. PowerHouse is a fixed 18V AC output transformer. The Legacy PowerMaster receives commands from the Legacy Base (sent from a Cab2 remote). Powermaster can either pass that Voltage straight thru in Command mode or provide a variable AC voltage output in Conventional mode, controlled by the Legacy Cab2.
@VJandP One more thing of note in the 3-rail electrical lexicon, there is a distinction between insulated and isolated. When it comes to electrically separating track blocks, you'd be wanting isolation (an electrical gap in the center rail power).
Insulated rails typically refer to separation of the ground between two outside rails on a track section, and is often used in operating accessories. In that Insulated track section, there is also a gap in one of the outside rails at each end of that insulated section. When the metal train wheels/axles enter that section they complete the ground circuit to the accessory.
