High-Voltage Connection Making the high-voltage connection is easy because the windings are wired in series, and the branches in the diagram are simply connected to form a larger “Y”, Figure 25‑52. Wires 4 and 7 are connected. Wires 5 and 8 are connected. Wires 6 and 9 are connected. The incoming power supply wires are always connected to wires 1, 2, and 3. For high voltage, there are two wires at each connection, and the current flows through four windings before exiting through another supply wire. Each wire connection should be made with a wire nut and secured with electrical tape. Low-Voltage Connection The parallel connections up for low voltage are more complicated than for high voltage, but the “Y” principle is still used. As shown in Figure 25‑53, L 1 is connected to wires 1 and 7. L 2 is connected to wires 2 and 8. L 3 is connected to wires 3 and 9. Wires 4, 5, and 6 are connected to each other. For low voltage, there are three wires at each connection, and the current flows through two windings before exiting through another supply wire. Resistance Check of Windings The motor windings on a three-phase motor can be checked with an ohmmeter. If a resistance The three incoming power supply wires are always connected to motor wires l, 2, and 3. Except for direction of rotation, it does not make any difference which supply wire is connected to which terminal since the supply wires are the same. 1 4 5 2 8 9 3 6 7 Goodheart-Willcox Publisher Figure 25‑50. A schematic of wye-connected, dual- voltage, three-phase motor windings shows the numbering for all nine wires. 1 4 7 9 6 3 8 5 2 L1 L2 L3 Goodheart-Willcox Publisher Figure 25‑51. Constructing a “Y” diagram and numbering the wires on a dual-voltage, three-phase motor. The spiral arrow shows the proper sequence for numbering the ends of the windings. L3 L1 L2 4 7 8 5 2 9 6 3 Connected Connected Connected 1 Goodheart-Willcox Publisher Figure 25‑52. The high-voltage connection places the windings in series. Wires 4 and 7 are connected, as are wires 5 and 8 and also wires 6 and 9. Power supply wires always go to 1, 2, and 3. 512 Heating and Cooling Essentials Copyright Goodheart-Willcox Co., Inc.