Three-phase device with windings X1-X2, Y1-Y2, Z1-Z2. In a Delta configuration, which connection scheme wires the device to incoming conductors A, B, and C?

Three-phase device with windings X1-X2, Y1-Y2, Z1-Z2. In a Delta configuration, which connection scheme wires the device to incoming conductors A, B, and C?

• A. A to x1 and z2, B to x2 and y1, C to y2 and z1
• B. A to x2 and y1, B to z2 and x1, C to y2 and z2
• C. A to y1 and z1, B to x1 and z2, C to x2 and y2
• D. A to z1 and x1, B to y2 and z2, C to x2 and y1

Answer: (A)

In a delta connection the windings are tied end-to-end to form a closed triangle, and each incoming line connects to the junction where two windings meet. Put the windings as X between X1 and X2, Y between Y1 and Y2, and Z between Z1 and Z2. To form the delta, tie Z2 to X1, tie X2 to Y1, and tie Y2 to Z1. The three line conductors then connect to those three junctions: A to the joint of X1 and Z2, B to the joint of X2 and Y1, and C to the joint of Y2 and Z1. This is the configuration that wires the device to A, B, and C correctly. Other options would connect lines to ends that aren’t the delta joints, which isn’t how a delta is completed.

In a delta connection the windings are tied end-to-end to form a closed triangle, and each incoming line connects to the junction where two windings meet. Put the windings as X between X1 and X2, Y between Y1 and Y2, and Z between Z1 and Z2. To form the delta, tie Z2 to X1, tie X2 to Y1, and tie Y2 to Z1. The three line conductors then connect to those three junctions: A to the joint of X1 and Z2, B to the joint of X2 and Y1, and C to the joint of Y2 and Z1. This is the configuration that wires the device to A, B, and C correctly. Other options would connect lines to ends that aren’t the delta joints, which isn’t how a delta is completed.