The generator is driven by a belt from the engine crankshaft.
The generator is a three-phase synchronous electric machine with electromagnetic excitation. To convert alternating current into direct current, a diode rectifier is built into the generator. Output voltage is adjusted by a built-in regulator. The generator has grounding by mass.
When the generator is operating, the electric current flowing through the excitation winding creates a magnetic flux around the rotor poles. When the rotor rotates, its magnetic poles periodically change under each stator tooth, as a result of which the magnetic flux passing through the teeth continuously changes in magnitude and voltage. This variable magnetic flux creates an electromotive force (EMF) in the stator winding. The wedge-shaped rotor pole pieces are selected in such a way that it allows obtaining a nearly sinusoidal EMF curve.
At high rotor speed, when the generator output voltage begins to exceed 13.6÷14.6 V, the voltage regulator is locked and the current does not pass through the excitation winding. When the voltage decreases, the regulator is unlocked again, allowing the current to pass freely through the excitation winding. The higher the rotor speed, the longer the regulator remains locked and, accordingly, the more the voltage at the generator output decreases. The process of locking and unlocking the regulator occurs at a high frequency, so the output oscillations remain practically unnoticeable and the generator voltage can be considered constant, maintained at the level 14.4 V.
The charging system does not require periodic maintenance, however, the condition of the alternator drive belt, battery and its wiring should be checked and replaced on a regular basis in accordance with the maintenance schedule (see sections Checking and caring for your battery and Checking the condition of the auxiliary drive belt Chapters Vehicle settings and routine maintenance).
When the ignition is turned on, the charge indicator on the instrument cluster should light up briefly (see chapter Controls and operating techniques). If the lamp does not turn off after starting the engine or lights up during its operation, check the condition of the charging system components. Failure to activate the lamp when the ignition is turned on indicates that it is out of order, the corresponding electrical wiring is damaged, or the generator is not functioning properly (including a broken drive belt).
Safety precautions when servicing a generator
- Do not disconnect the battery or voltage regulator while the engine is running;
- Do not short the generator excitation terminal or the cable attached to it to ground;
- Do not confuse the order of connecting the voltage regulator wiring;
- Remember that turning on a voltage regulator shorted to ground will cause it to fail immediately;
- Never remove the alternator while the battery is connected;
- Do not confuse the polarity of the battery connection;
- Never use voltage meters or test lamps connected to the household network (110/220 V) when checking on-board electrical equipment;
- When checking the condition of the diodes, do not apply a voltage higher than 12 V to them and do not use meggers that also have a high output voltage - a breakdown of the diodes will lead to a short circuit. Remember that when checking the insulation of the wiring with a megger, it is necessary to disconnect all the wiring from the generator;
- When charging the battery without removing it from the car, make sure that both wires are disconnected from it. Do not confuse the polarity of the charger connection;
- Before carrying out any electric welding work on the vehicle, do not forget to disconnect the electrical wiring from the generator and battery;
- Any checks of the circuits and components of the on-board electrical wiring should be carried out with the engine not running and the battery disconnected;
- Remember that reversing the polarity of any connections carries the risk of irreversible failure of the rectifier and generator voltage regulator.