Which type of CT has service conductors connected directly to a built-in bus bar?

The correct answer is Bar CT. This type of Current Transformer (CT) is designed with service conductors that connect directly to a built-in bus bar, allowing for efficient current measurement. The bar structure facilitates the flow of current through the bus bar, making installation and maintenance simpler compared to other CT types.

Window CTs are designed to encapsulate a conductor within a hollow core but do not connect directly to a bus bar. Bushing CTs are used in equipment like transformers and will typically connect through bushings rather than a built-in bus. Wound CTs have a coil or winding that measures current but also do not have a direct connection with a bus bar structure. Thus, Bar CT is distinct for its practical integration with service conductors, serving a specific application effectively.