In a balanced three-phase Y-connected system with line voltage V_L = 480 V, what is the phase voltage V_ph?

In a balanced three-phase Y-connected system with line voltage V_L = 480 V, what is the phase voltage V_ph?

• A. 480 V
• B. 346.41 V
• C. 277.13 V
• D. 277.13 kV

Answer: (C)

In a star (Y) connected system, the line voltage is √3 times the phase-to-neutral voltage. So the phase voltage is the line voltage divided by √3. With a line voltage of 480 V, V_ph = 480 / √3 ≈ 277.13 V (RMS). This is the voltage from any line to the neutral. The other values don’t fit the relationship for a Y-connected system.

In a star (Y) connected system, the line voltage is √3 times the phase-to-neutral voltage. So the phase voltage is the line voltage divided by √3. With a line voltage of 480 V, V_ph = 480 / √3 ≈ 277.13 V (RMS). This is the voltage from any line to the neutral. The other values don’t fit the relationship for a Y-connected system.