Where is the primary fuse located on a CSP transformer?

The primary fuse of a CSP (Current-Sensing Potential) transformer is typically located inside the tank, positioned between the primary coil and the primary bushing. This placement is critical for operational integrity and safety, as it allows the fuse to protect the transformer from overcurrent conditions.

By being located inside the tank, the fuse is shielded from environmental factors, which helps maintain its reliability and performance over time. This configuration also allows for effective monitoring and efficient operation of the transformer by ensuring that any issues related to primary current can be detected and dealt with appropriately within the secure confines of the transformer’s structure.

In contrast, the other locations suggested do not provide the same level of protection or practicality; placing a fuse at the top of the tank or near the exterior exposes it to potential damage from external conditions. The secondary side is not appropriate for the primary fuse, as it serves a different function related to the output, thereby underscoring why option B is the correct choice.