What is the main benefit of having two sets of field windings in an electric motor?

Having two sets of field windings in an electric motor primarily enables the motor to operate in either direction. This design facilitates the reversal of the motor's magnetic field, which allows for bidirectional operation. By altering the current flow through the windings, the direction in which the motor turns can be easily changed, making it versatile for various applications that require directional control.

In contrast, the other options do not accurately reflect the primary benefit of dual field windings. For example, while increased energy efficiency and reduced maintenance might be valuable features of certain motor designs, they are not directly attributed to having two sets of field windings. Similarly, higher operational sound levels are not a benefit associated with this design feature. Thus, the ability to operate in either direction stands out as the central advantage of employing two sets of field windings in an electric motor.