What is the nameplate primary voltage rating when transformers are banked in a wye on a 12.5-kilovolt, 4-wire circuit?

The nameplate primary voltage rating for transformers banked in a wye connection on a 12.5-kilovolt, 4-wire circuit is correctly identified as 7,200/12,470Y V. In a typical wye system, the line-to-line voltage is 1.732 times the line-to-neutral voltage. For a system rated at 12.5 kV, the line-to-line voltage can be converted to the corresponding line-to-neutral voltage by dividing by the square root of 3 (approximately 1.732).

Calculating this, you find that the line-to-neutral voltage is about 7,250 volts, leading to an industry-standard designation rounded to 7,200 volts for clarity and consistency. The line-to-line voltage for the wye-connected transformers in this scenario is then represented as 12,470 volts.

This naming convention allows for easier reference in installation and maintenance. It is common in the industry to round these voltages to the nearest standardized value, which is why the correct answer reflects these specific values. The other options do not align with the standard practices for naming voltage ratings in a wye configuration for this system voltage, making them less appropriate choices.