Question 232Electricity & Electronics - Assistant Engineer

The correct answer is C) If the overall plant has a unity power factor, the synchronous motor is normally-excited. This is correct because when the overall plant has a unity power factor, the synchronous motor should be operated in a normally-excited state. In this condition, the synchronous motor is able to maintain the unity power factor of the overall plant, which is the ideal power factor for efficient operation. The other options are incorrect because they do not accurately describe the relationship between the plant's power factor and the excitation state of the synchronous motor. For example, if the plant has a lagging power factor, the synchronous motor would need to be over-excited to correct the power factor, not normally-excited as stated in option B.