In a three-phase system, what is meant by a phase?

In a three-phase system, what is meant by a phase?

• A. One of the three AC waveforms, 60 degrees apart
• B. A neutral conductor
• C. One of the three AC waveforms, 120 degrees apart, supplying power
• D. The ground reference

Answer: (C)

In a three-phase system, a phase is one of the three sinusoidal voltage (or current) waveforms that supply power together. These waveforms are offset in time by 120 electrical degrees, so when one is at a peak, the others are at different points in their cycles, allowing smooth and continuous power delivery. That’s why the best description is that a phase is one of the three AC waveforms, 120 degrees apart, supplying power. The neutral conductor is the return path, not a phase, and the ground reference is safety grounding, not a phase. Also, the phases are spaced by 120 degrees, not 60 degrees.

In a three-phase system, a phase is one of the three sinusoidal voltage (or current) waveforms that supply power together. These waveforms are offset in time by 120 electrical degrees, so when one is at a peak, the others are at different points in their cycles, allowing smooth and continuous power delivery. That’s why the best description is that a phase is one of the three AC waveforms, 120 degrees apart, supplying power. The neutral conductor is the return path, not a phase, and the ground reference is safety grounding, not a phase. Also, the phases are spaced by 120 degrees, not 60 degrees.