1. Generating Voltage:
- An alternator uses a rotating magnetic field to induce an electrical current in its stator windings.
- The strength of this magnetic field, and therefore the output voltage, is controlled by:
- Field current: The alternator's rotor has its own winding, called the field winding. The current flowing through this winding determines the strength of the magnetic field.
- Speed: The faster the rotor spins, the higher the output voltage.
- The alternator's internal regulator adjusts the field current to maintain a constant output voltage, regardless of the load.
2. Load and Current:
- The alternator generates a specific voltage (usually around 13-14 volts in a car).
- The amount of current drawn from the alternator depends on the resistance of the load connected to it.
- Ohm's Law describes this relationship: Current (I) = Voltage (V) / Resistance (R).
- High resistance means low current, and low resistance means high current.
3. Examples:
- When your car's headlights are turned on, they present a lower resistance than the rest of the electrical system. This leads to a higher current being drawn from the alternator to power the headlights.
- If you turn on the air conditioner, the compressor draws a lot of current, causing the alternator to work harder.
In summary:
- The alternator produces a specific voltage.
- The amount of current drawn from the alternator depends on the load connected to it.
- The alternator adjusts its output to meet the needs of the load, within its limits.
It's important to note that an alternator has a maximum current output that it can provide. If the load demands more current than the alternator can supply, the voltage will drop, and the alternator may overheat or fail.