Question 112Electricity & Electronics - 1st Asst/Chief

The correct answer is A) The alternator output voltage must be decreased proportionately downward with the frequency decrease. When an alternator is operated at a frequency lower than its rated frequency, the magnetic field and induced voltage in the alternator windings decrease proportionately. To maintain the proper voltage output, the alternator voltage must be decreased in proportion to the decrease in frequency. This relationship is based on the fundamental principles of electromagnetic induction that govern the operation of alternators. The other options are incorrect because: B) Increasing the voltage would not be appropriate to compensate for the frequency decrease; C) Maintaining the rated voltage would result in an imbalance between the frequency and voltage; and D) It is permissible to operate an alternator at up to 5% below its rated frequency, as long as the voltage is adjusted accordingly.