Which description best matches a 3-wire 3-phase corner-grounded delta system?

Which description best matches a 3-wire 3-phase corner-grounded delta system?

• A. A delta with one corner connected to earth
• B. A delta with all corners connected to earth
• C. A wye with neutral connected to earth
• D. A delta with center point grounded

Answer: (A)

The key idea is corner-grounded delta: in a delta connection you have three windings forming a triangle, and grounding one corner gives a reference point to earth. That makes it a three-phase, three-wire system with no separate neutral conductor, because the grounded corner serves as the earth reference rather than a distinct neutral path. This is exactly described by a delta with one corner connected to earth. Why the other descriptions don’t fit: grounding every corner would effectively short the windings and isn’t a functional configuration; a wye arrangement with neutral tied to earth introduces a neutral conductor and is a different system (not a delta and not a 3-wire delta); grounding the center point of a delta is a different grounding scheme altogether and does not describe a corner-grounded delta.

The key idea is corner-grounded delta: in a delta connection you have three windings forming a triangle, and grounding one corner gives a reference point to earth. That makes it a three-phase, three-wire system with no separate neutral conductor, because the grounded corner serves as the earth reference rather than a distinct neutral path. This is exactly described by a delta with one corner connected to earth.

Why the other descriptions don’t fit: grounding every corner would effectively short the windings and isn’t a functional configuration; a wye arrangement with neutral tied to earth introduces a neutral conductor and is a different system (not a delta and not a 3-wire delta); grounding the center point of a delta is a different grounding scheme altogether and does not describe a corner-grounded delta.