How can three-phase motors be operated?

Three-phase motors are designed to operate on three-phase electrical systems, which provide a consistent and balanced power output. The correct answer reflects an essential aspect of how three-phase motors can be connected and utilized in practical settings.

In option B, the description of operating a three-phase motor at 230 V on one phase and 115 V on the other two phases illustrates a method known as phase transformation or branch circuit connection. This setup allows for the motor to function effectively when powered by lower voltage phases, using a specific configuration. It's important to note that while most three-phase motors require balanced and direct three-phase power, they can also run on different voltage levels depending on the winding setup and motor design.

This flexibility in operating voltage is particularly useful in systems where standard three-phase supplies may not be readily available at specific voltage levels. In contrast, the other options either suggest limitations that are not accurate for three-phase motors or propose configurations that do not align with standard electrical practices for properly operating such motors.