The vehicles are equipped with alternating current generators.
When installing additional electrical equipment, ensure that the generator has sufficient capacity to power this equipment. The main elements
the generator consists of a rotor, stator, rectifier, commutator brushes, electronic voltage regulator, bearings and belt pulley.
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 to direct current, a diode rectifier is built into the generator.
The voltage is regulated by a built-in electronic voltage regulator.
When the generator is running, the electric current flowing through the excitation winding creates a magnetic flux around the rotor poles. When the rotor rotates, the south and north poles of the rotor pass under each stator tooth; the working magnetic flux passing through the stator teeth changes in magnitude and voltage. The alternating magnetic flux creates an electromotive force in the stator winding. The wedge-shaped form of the rotor pole pieces is selected in such a way that it allows obtaining a waveform of the electromotive force that is close to sinusoidal.
At high generator rotor speed, when the generator voltage becomes greater than 13.6–14.6 V, the voltage regulator is locked and current does not pass through the excitation winding. The generator voltage drops, the regulator opens and again passes current through the excitation winding. The higher the generator rotor speed, the longer the regulator is in the locked state, and therefore the more the voltage at the generator output decreases. The process of locking and unlocking the regulator occurs at a high frequency, so the voltage fluctuations at the generator output are imperceptible; it can practically be considered constant, maintained at a level of 13.6–14.6 V.
When checking the generator, as well as when operating the vehicle, it is necessary to follow a number of rules to avoid damaging the generator:
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- do not allow the generator to operate with the battery disconnected from the generator terminal. Without a battery, dangerous surges occur in the vehicle's electrical system when any electrical consumers are disconnected. These surges can damage the vehicle's electronics, including the voltage regulator and the generator's rectifier diodes;
- do not test the generator's performance by sparking, even by briefly connecting the positive terminal of the generator to ground. This will cause significant current to flow through the diodes, which will damage them. The generator voltage can only be monitored with a voltmeter;
- the negative terminal of the battery must always be connected to the vehicle ground, and the positive terminal to the generator terminal. Incorrect (reverse) connection of the battery will immediately cause increased current to flow through the generator diodes, and they will fail;
- do not test diodes with a voltage higher than 12 V or with a megohmmeter, as the voltage is too high for diodes and they will be broken during testing (a short circuit will occur). When checking the insulation of electrical wiring with a megohmmeter, it is necessary to disconnect all wires from the generator;
- when electric welding any body parts, it is necessary to disconnect all wires from the generator and battery;
- electrical circuits and components must be checked and faults must be eliminated with the engine off and the battery disconnected.