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How to Wire a High & Low Voltage Three-Phase Motor

Working with three-phase power and motors that operate on three-phase power is confusing if you have never attempted it before. Three-phase power consists of three different AC power lines that differ in the timing of their peak voltage. Connecting a three-phase motor to your power source can take one of two forms depending on the style of motor windings used by the manufacturer. Motors are available in Y-style windings and Delta-style windings. The style determines how to connect the wires to the power source.

Things You'll Need

Multimeter
Wire nuts

Instructions

- 1
  Determine the style windings on your motor. Then label each wire with a number between 1 and 9.
- 2
  Use the multimeter set to test continuity to check which wires connect within the motor. For a Y-style motor, the following sets of wires show connectivity: 1-6, 2-5, 3-6 and 7-8-9. For a Delta-style motor, the following sets of wires show connectivity: 7-2-5, 4-1-9 and 6-3-8.
- 3
  Set the motor to high voltage by using wire nuts to connect wire 6 to wire 9, wire 5 to wire 8 and wire 4 to wire 7 on a Y-style motor. On a Delta-style motor, use wire nuts to connect wire 6 to wire 9, wire 4 to wire 7 and wire 5 to wire 8. These connections utilize all the windings on the motor. Then connect power lines to wires 1, 2 and 3. The connection of the power lines to the motor is the same regardless of whether you are using a Y-style or Delta style motor.
- 4
  Set the motor for low voltage by connecting wires 4, 5 and 6 together on a Y-style motor and connecting the power lines to wires 1, 2 and 3. Connect the three power lines to a Delta-style motor by using a wire nut to tie the following sets of wires together, 1, 6 and 7 to power line 1; 2, 4 and 8 to power line 2; and 3, 5 and 9 to power line 3.

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