Some motors are constructed to operate on either of two voltages. When connected to operate on the lower voltage, the windings are connected in:

When motors are designed to operate on either of two voltages, connecting the windings in parallel for the lower voltage allows for the proper operation under those conditions. In a parallel configuration, each winding experiences the full supply voltage, enabling the motor to operate efficiently at the lower voltage rating.

When connected in parallel, the current through each winding is divided, which helps to spread the load effectively across the windings. This setup ensures that the motor can still function optimally without overheating or drawing excessive current, which might occur if it were connected in series.

On the other hand, using series or combination configurations would not supply the necessary voltage to each individual winding when operating at the lower voltage, likely leading to inadequate performance or failure to start. The isolation choice does not pertain to winding configurations and is irrelevant in this context. Therefore, connecting the windings in parallel for lower voltage operation is indeed the correct approach.