Which transformer is responsible for isolating AC system conductors, but not the AC grounding conductor?

The correct answer is an isolation transformer. An isolation transformer is specifically designed to decouple the AC conductors from the source of the electrical supply, providing a level of safety by preventing electrical shock and protecting equipment from surges and faults. Importantly, it does not isolate the AC grounding conductor, allowing it to maintain a connection to ground for safety and stability.

In contrast, a polarization transformer is used primarily for applications where phase relationships need to be maintained, not specifically for isolating conductors. A grounding transformer is used to create a neutral point in systems where there is no grounded conductor, making it focused on grounding functions rather than isolation. A voltage transformer, on the other hand, is used to step down voltage levels for measurement or control, and it does not serve the same isolation purpose as an isolation transformer. Thus, the isolation transformer is the correct choice for isolating AC system conductors while keeping the AC grounding conductor connected.