The described supply system type is best classified as which of the following?

The described supply system type is best classified as which of the following?

• A. Three-wire three-phase corner-grounded delta
• B. Three-wire three-phase wye with neutral
• C. Four-wire delta
• D. Three-wire single-phase delta

Answer: (A)

In a delta system, the three windings are connected in a triangle. If one corner of that triangle is bonded to earth, you get a grounded corner and a three-wire setup with no separate neutral conductor. This gives you three current-carrying conductors and earth as the reference point, which is exactly what a corner-grounded delta is. The description’s emphasis on a grounded point in a three-wire, three-phase configuration points to this arrangement, rather than a wye with a neutral (which would supply a neutral conductor), a four-wire delta (which includes a neutral path from a center-tapped winding), or a single-phase delta (which isn’t three-phase). So the best fit is a three-wire three-phase corner-grounded delta.

In a delta system, the three windings are connected in a triangle. If one corner of that triangle is bonded to earth, you get a grounded corner and a three-wire setup with no separate neutral conductor. This gives you three current-carrying conductors and earth as the reference point, which is exactly what a corner-grounded delta is. The description’s emphasis on a grounded point in a three-wire, three-phase configuration points to this arrangement, rather than a wye with a neutral (which would supply a neutral conductor), a four-wire delta (which includes a neutral path from a center-tapped winding), or a single-phase delta (which isn’t three-phase). So the best fit is a three-wire three-phase corner-grounded delta.