In a three-phase wye connection, line-to-line voltage is related to line-to-neutral by V_line = sqrt(3) × V_phase. If V_line = 480 V, what is V_phase to the nearest volt?

• A. 553 V
• B. 480 V
• C. 277 V
• D. 165 V

Answer: (C)

In a three-phase wye system, the line-to-line voltage is sqrt(3) times the line-to-neutral (phase) voltage because the three phase voltages are 120 degrees apart and the line-to-line voltage is the vector difference between two of them. Therefore, the phase voltage is V_phase = V_line / sqrt(3). With V_line = 480 V, V_phase = 480 / 1.732 ≈ 277.1 V, which rounds to 277 V. This is the value that satisfies the relationship, while the other options do not fit the sqrt(3) relationship.