In a three-phase system, the three phase voltages are separated by 120 degrees and are commonly configured as either delta or wye.

• A. True
• B. False
• C. Only 90-degree separation is used
• D. They are always DC

Answer: (A)

Three-phase power uses three sinusoidal voltages that are 120 electrical degrees apart, which allows for a smooth, rotating magnetic field and steady power delivery. These voltages are generated by windings spaced 120 degrees apart and can be connected in either delta or wye. In both configurations the phase voltages stay 120 degrees apart; the choice of delta or wye changes how line voltages relate to those phase voltages (for example, in a wye the line voltage is sqrt(3) times the phase voltage, while in delta the line voltage equals the winding voltage). The key point is the 120-degree separation remains, regardless of connection type. The other options are incorrect because 90-degree separation does not constitute a standard three-phase set, and three-phase power is AC, not DC.