Three-Phase Dual Voltage Motor Wiring

dual voltage motors1

 

It is more economical for manufacturers to make three-phase motors with dual windings. A nine-lead motor of the type shown here can be connected for either 230-V or 460-V operation.

The figure on the left shows how a nine-wire dual-voltage motor is connected in a wye configuration. Here the leads are connected in parallel for 230-V operation. This means that the 230 V of Line 1 will be applied to both windings A and D at the same time. Likewise, the 230 V of Line 2 will be applied to windings B and E at the same time, and the 230 V of Line 3 will be applied to windings C and F at the same time. Therefore, the same voltage will be impressed across each of the windings.

In the figure on the right, the leads are connected in series for 460-V operation. This means that the 460 V from LI and L2 will be impressed across windings A, D, B, and E. The 460 V from LI and L3 will be impressed across windings A, D, C, and F. The 460 V from L2 and L3 will be impressed across windings B, E, C, and F.

EXCERPT FROM ELECTRICITY FOR HVACR TECHNICIANS available from the online store at RSES (Refrigeration Service Engineers Society) The HVACR Training Authority

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