For the same 3Ø, 4-W open-delta bank, the line voltage equals ___.

For the same 3Ø, 4-W open-delta bank, the line voltage equals ___.

• A. Ecoil (or winding)
• B. Ecoil (or winding) × 1.732
• C. Ecoil (or winding) ÷ 1.732
• D. Ecoil (or winding) × 0.5

Answer: (A)

Open-delta arrangements use windings connected between two lines, so each transformer winding is across the line-to-line voltage. In this delta-like connection, the coil (winding) voltage equals the system line voltage. Therefore the line voltage is the same as Ecoil (or winding) value. If you were in a wye (star) connection, the relation would be different (line voltage would be √3 times the phase voltage). But in this open-delta bank, the windings see the line-to-line voltage directly, so Ecoil equals the line voltage.

Open-delta arrangements use windings connected between two lines, so each transformer winding is across the line-to-line voltage. In this delta-like connection, the coil (winding) voltage equals the system line voltage. Therefore the line voltage is the same as Ecoil (or winding) value.

If you were in a wye (star) connection, the relation would be different (line voltage would be √3 times the phase voltage). But in this open-delta bank, the windings see the line-to-line voltage directly, so Ecoil equals the line voltage.