In which scenario would you find a wye-delta transformer configuration?

A wye-delta transformer configuration is commonly used in high voltage distribution systems primarily due to its advantages in balancing loads and providing better voltage regulation. In this setup, the wye configuration on one side allows for a neutral point which can help manage phase imbalances and provide grounding, while the delta configuration on the other side is effective in supplying three-phase loads without a neutral.

This arrangement is particularly beneficial in high voltage applications, where maintaining stable voltage levels and efficient power distribution across multiple phases is critical. The wye-delta transformation also aids in reducing the risk of circulating currents and enhances the system's ability to manage transient conditions, which are common in high voltage distribution frameworks.

In contrast, the other scenarios mentioned do not typically involve this configuration. Single-phase loads would not require a three-phase transformer arrangement like wye-delta. Low power transmission situations generally do not necessitate the complexities and advantages that come with this transformer setup. Similarly, while isolation between power and control circuits is critical, it is usually accomplished using different transformer configurations tailored for isolation purposes rather than relying on a wye-delta configuration, which focuses more on handling three-phase systems efficiently.