What can negatively impact the power factor in a synchronous motor?

The power factor in a synchronous motor is fundamentally influenced by how efficiently it converts electrical power into mechanical power and how effectively it interacts with the system’s reactive power. When there are improper DC currents in the rotor winding, it causes a disturbance in the magnetic field generated by the motor. This can lead to inadequate synchronism between the rotor's magnetic field and the stator's rotating magnetic field.

Synchrony is critical because the motor relies on this alignment to maintain efficient operation. If the rotor does not have the proper excitation due to incorrect DC currents, the magnetic forces that drive the motor can be weakened or misaligned, leading to an increase in reactive power demand and ultimately causing a poor power factor. This situation typically renders the motor less efficient and can lead to operational instability.

In contrast, while high rotor speeds, faulty wiring connections, and excessive loads can impact motor performance, they do not directly relate to the primary function of the rotor's excitation and its role in maintaining an appropriate power factor like improper DC currents do.