Which current transformer type allows current-carrying conductors to pass through it?

The correct answer is the Window CT, which is designed specifically to allow current-carrying conductors to pass through its core without requiring any physical connections. This design consists of a hollow core that forms a "window" through which the conductor can be inserted. This feature makes Window CTs particularly advantageous in applications where it is impractical to break the circuit in order to install a current transformer, allowing for easy installation and maintenance.

In contrast, other types like the Wound CT typically require an input winding to be connected to the conductor, which means the conductor cannot pass through the transformer without being physically rewired. Bushing CTs are often integrated into electrical bushings and are designed primarily for substation equipment, not for conducting multiple cables through the center. Bar CTs usually require a specific bar-shaped conductor to be installed within them, limiting their use to specific applications and geometries. Thus, the Window CT stands out for its flexibility and ease of installation in various settings.