In a 480/277 V system, what is the line-to-line voltage between phase B and phase C?

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Multiple Choice

In a 480/277 V system, what is the line-to-line voltage between phase B and phase C?

Explanation:
In a three-phase wye system, the line-to-line voltage is √3 times the phase-to-neutral voltage. Here the phase-to-neutral is 277 V, so the line-to-line voltage is 277 × √3 ≈ 480 V. You can see this by phasor math: Va = 277∠0°, Vb = 277∠-120°, and the difference Vab = Va − Vb has magnitude 277√3 ≈ 480 V. Therefore the line-to-line voltage between phase B and phase C is about 480 V.

In a three-phase wye system, the line-to-line voltage is √3 times the phase-to-neutral voltage. Here the phase-to-neutral is 277 V, so the line-to-line voltage is 277 × √3 ≈ 480 V. You can see this by phasor math: Va = 277∠0°, Vb = 277∠-120°, and the difference Vab = Va − Vb has magnitude 277√3 ≈ 480 V. Therefore the line-to-line voltage between phase B and phase C is about 480 V.

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