Hi, I found this Lionel starter set in an online store and I'd like to buy it, I have doubts because the box says power DC while I have a layout with an AC transformer, another thing I don't understand is the scale , what does o27 mean? Can it run on modern O scale Fastracks?
Glad you noticed that. It is a DC locomotive, so you'd need to convert it. There's a discussion about it at https://www.modeltrainforum.com/threads/power-supply-fro-8512-dc-engine.89690/ 027 is/was Lionel's tightest radius curve and its rail is of smaller size too per the illustration below. Some larger locomotives will not run on 027, like the F-3, GG-1, FM Trainmaster, 2-8-4, 4-8-4, 4-6-4, etc.). Eight sections of 027 curved track make a circle that is 27 Inches in diameter on the outer rail, about 25" diameter using the center rail. Lionel's legacy of track variants (O-72, O, O-27, O-36, Super-O and Fastrack) all get pretty confusing.
Hardcoaler is right, you either have to convert it to run on AC or only run it on its own track using a DC power pack, either the one included in the set or another one. It will run on FasTrack using a DC power pack. It is a conventional control only engine. It cannot be controlled using a remote like LionChief.