What is the primary voltage rating threshold for identifying a subtractive transformer?

A subtractive transformer is identified primarily based on its voltage rating, which is critical for understanding its operation and application in electrical systems. The correct threshold for identifying a subtractive transformer is above 8,660 volts. This specification indicates the high-voltage transformers designed to step down voltage levels for safe distribution and use in various electrical applications.

The significance of this threshold lies in its alignment with industry standards and practices. Transformers that operate above this voltage rating generally deal with more extensive power distribution networks, where voltage management becomes crucial for safety and efficiency.

In contrast, the other options present irrelevant or incorrect parameters for subclassifying transformers. Specifications such as kVA ratings focus on the power capacity rather than operating voltage, which does not pertain to the subtractive transformer classification. Thus, any ratings under 8,660 volts or those based solely on kVA do not capture the defining characteristics necessary for identifying a subtractive transformer.