The correct answer is B.
When the applied voltage of a synchronous motor goes down, the motor will draw more current to maintain the same torque output. This increased current will cause the power factor of the motor to decrease.
The power factor of a synchronous motor is the ratio of the real power (kW) to the apparent power (kVA). The real power is the power that is used to do work, while the apparent power is the total power that is drawn from the power supply. The power factor is a measure of how efficiently the motor is using the power supply.
A lagging power factor means that the motor is drawing more reactive power (kVAr) than it is using real power (kW). This reactive power is used to create a magnetic field in the motor, but it does not contribute to the actual work that the motor is doing.
When the applied voltage of a synchronous motor goes down, the motor will draw more current to maintain the same torque output. This increased current will cause the motor to draw more reactive power, which will cause the power factor to decrease.
The following is a brief explanation of each option:
- Option A: The power factor will remain the same. This is not correct because the power factor will decrease when the applied voltage goes down.
- Option B: The power factor will go down. This is the correct answer.
- Option C: The power factor will improve. This is not correct because the power factor will decrease when the applied voltage goes down.
- Option D: None of the above. This is not correct because Option B is the correct answer.