How is a 9-lead motor connected for high voltage (example 460 V)?

• A. Connect 4-6 to neutral; 1&7 to L1; 2&8 to L2; 3&9 to L3; coils in series.
• B. Connect 1&7 to L1, 2&8 to L2, 3&9 to L3; 4,5,6 together (neutral).
• C. Connect 4-6 to L1; 1-3 to neutral; 7-9 to L3.
• D. All windings are connected in parallel across L1-L3.

Answer: (B)

High voltage operation on a 9-lead motor is achieved by putting windings in series for each phase and using a common neutral point. The nine leads include the ends of three windings per phase and the junctions between windings. By tying the junction leads together, you create a neutral point for all three phases. Then you connect each line to the outer ends of the two windings that form that phase, so each phase has two windings in series across the supply.

In practice for a high-voltage hookup, connect the two outer leads of each phase to the corresponding supply line and join the three middle leads as the neutral: connect L1 to the two leads that form phase A, L2 to the two that form phase B, and L3 to the two that form phase C, while tying 4, 5, and 6 together as the neutral. This places two windings in series per phase, allowing operation at higher voltages such as 460 V.