What is the primary function of an alternator in a power system?

The primary function of an alternator in a power system is to charge the battery and power the electrical systems in a vehicle or other equipment. An alternator generates alternating current (AC) through electromagnetic induction. This AC is then converted into direct current (DC) before it is used to charge the battery and supply power to the vehicle's electrical components, such as lights, radio, and ignition system. The alternator plays a crucial role in ensuring that the battery remains charged while also delivering the necessary current for the operation of the electrical system, especially when the engine is running.

The other options describe functions that are not the primary role of an alternator. Generating power for long-distance transport refers more to generators used in power plants. Converting DC power to AC power is typically the role of an inverter, not an alternator. Measuring electrical current is a function for devices like ammeters or current sensors, rather than being within the scope of an alternator's functionalities.