In figure "4" of the diagram in the illustration, the three phase step down power transformer has a turns ratio of five to one. If a three-phase 4160 volt supply is connected to terminals "A1-B1-B2", what voltage should develop across terminals "A2- B2-C2"? Illustration EL-0084

Correct Answer: Option C — 480 volts

In a 3-phase step-down transformer with a 5:1 turns ratio, line-to-line voltage is reduced proportionally. Dividing the 4160V primary supply by the 5:1 ratio yields 832V. Per IEEE 45 and 46 CFR Subchapter J standards, transformer ratios govern transformation of high-voltage shipboard distribution down to auxiliary levels.