When a 3Ø, 4-W supply system delivers 277/480 volts, the system has line-to-line voltages that are ___ volts.

When a 3Ø, 4-W supply system delivers 277/480 volts, the system has line-to-line voltages that are ___ volts.

• A. 120
• B. 480
• C. 277
• D. 208

Answer: (B)

In a three-phase wye (3Ø) system, the line-to-line voltage is equal to the line-to-neutral voltage multiplied by the square root of 3. For a 277/480 V system, the line-to-neutral voltage is 277 V, so the line-to-line voltage is 277 × √3 ≈ 479.8 V, commonly referred to as 480 V. Thus the line-to-line voltages are about 480 volts. The 277 V value is the line-to-neutral voltage, and 208 V or 120 V would correspond to different system configurations.

In a three-phase wye (3Ø) system, the line-to-line voltage is equal to the line-to-neutral voltage multiplied by the square root of 3. For a 277/480 V system, the line-to-neutral voltage is 277 V, so the line-to-line voltage is 277 × √3 ≈ 479.8 V, commonly referred to as 480 V. Thus the line-to-line voltages are about 480 volts. The 277 V value is the line-to-neutral voltage, and 208 V or 120 V would correspond to different system configurations.