When the ignition is turned on, voltage from the storage battery 1 is supplied to the terminal "B" of the voltage regulator through contacts "30" and "87" of the ignition relay 6, fuse "5" and through the control lamp 8 and resistors 4 of the mounting block 3 connected in parallel. Control lamp 8 lights up, signaling that the excitation winding is powered from the storage battery.
The electric current flowing through the excitation winding creates a magnetic flux around the rotor poles. As the rotor rotates, the south and north magnetic poles of the rotor pass under each stator tooth, and the working magnetic flux passing through the stator teeth changes in magnitude and direction. This variable magnetic flux creates an electromotive force in the stator winding. The beak-shaped rotor pole pieces are selected in such a way that it allows obtaining a nearly sinusoidal shape of the electromotive force curve.
In a properly functioning generator, the voltage taken from three additional diodes 14 and acting on the "B" terminal of the voltage regulator is equal to the voltage on the "30" terminal. Therefore, there is no potential difference between the "30" terminal and the "61" terminal of the generator. No current flows through the control lamp 8 and it does not light. The excitation winding is powered by three additional diodes 14, the battery is charged by the generator.
If the generator is faulty, it either does not generate voltage at all, or it is less than the battery voltage. Therefore, a potential difference arises between terminal "30" and terminal "61" of the generator, under the action of which current flows from the battery through the control lamp 8 and the excitation winding 11. The control lamp lights up, signaling that the generator is faulty and the battery is discharging. A voltmeter 9 is used for precise control of the generator voltage.
At high rotor speed, when the generator voltage becomes more than 13.6...14.6 V, the voltage regulator 10 is locked and the current does not pass through the excitation winding. The generator voltage drops, the regulator unlocks and again passes the current through the excitation winding. The higher the generator rotor speed, the longer the regulator is locked, and therefore, the more the voltage at the generator output decreases. The process of locking and unlocking the regulator occurs with a high frequency. Therefore, the voltage fluctuations at the generator output are unnoticeable and it can practically be considered constant, maintained at a level of 13.6...14.6 V.
The article is taken from an online resource vazbook.ru