Which configuration has three phase conductors plus a neutral?

• A. Delta
• B. Open delta
• C. Wye
• D. Grounded delta

Answer: (C)

In a three-phase system, the wye (Y) connection ties the ends of all three phase windings to a common neutral point, while the other ends go to the three power lines. This creates four conductors: three phase lines plus a neutral. The neutral serves as a return path for unbalanced single-phase loads and allows line-to-neutral voltages to be used (for example, 120 V from each phase to neutral in common North American distributions, or 277 V in other voltage classes). In balanced operation the neutral current is zero, but it’s still there to support single-phase loads and derive voltages from line to neutral. The other configurations either connect windings in a closed loop without a neutral (delta), or are arrangements that don’t provide a standard three-phase-plus-neutral four-wire system (open delta, grounded delta). Therefore, the configuration with three phase conductors plus a neutral is the wye.