What high side rating indicates a transformer is suitable for a wye connection only?

The high side rating that indicates a transformer is suitable for a wye connection only is typically characterized by a grounded wye configuration. In this case, the choice labeled with a high side rating of 12470GRDY/7200- explicitly mentions "GRDY," which signifies that the transformer is grounded, highlighting its suitability for a wye connection.

In a wye (or star) configuration, the neutral point is typically grounded, allowing for the protection of equipment and safety measures in the electrical system. This grounding means that the transformer can handle phase-to-ground fault conditions effectively, which is integral to many distribution networks.

Other choices either do not indicate such a grounding or specify configurations more common to delta connections or split-phase systems, which are not designed to exclusively support a wye configuration. For example, the options that reference lower voltage ratings or split-phase configurations lack the specific reference to grounding, making them unsuitable for the characteristics of a wye connection.