Alternator - General Information and Precautions

GENERAL INFORMATION

The vehicle is equipped with an AC alternator. When installing additional electrical equipment, make sure the alternator output is sufficient to supply this equipment.

The alternator is driven by a V-ribbed belt from the crankshaft pulley.

The alternator is a three-phase synchronous electrical machine with electromagnetic excitation. A diode rectifier is built into the alternator to convert alternating current to direct current. Voltage is regulated by a built-in electronic voltage regulator.

When the alternator operates, the electric current flowing through the field winding creates a magnetic flux around the rotor poles. As the rotor turns, a south or north rotor pole passes each stator tooth in turn, and the working magnetic flux passing through the stator teeth changes in magnitude and direction. This alternating magnetic flux induces an electromotive force in the stator winding. The wedge-shaped form of the rotor pole pieces is selected so that the electromotive force curve is close to sinusoidal.

At high rotor speeds, when the alternator voltage exceeds 13.6 – 14.6 V, the voltage regulator switches off and no current flows through the field winding. The alternator voltage drops, the regulator switches on again and passes current through the field winding. The higher the rotor speed, the longer the regulator remains off, and therefore the more the output voltage drops. The regulator switches on and off at a high frequency, so the voltage fluctuations at the alternator output are not noticeable and the output can be considered practically constant, maintained at 13.6 – 14.6 V.

CAUTION

Before performing any work on the charging system, observe the following precautions:

PROCEDURE

1. Never disconnect the battery or the voltage regulator while the engine and alternator are running.

2. Never short the alternator field terminal or the cable connected to it to ground.

3. Never mix up the voltage regulator wires.

4. Never energize the voltage regulator if it is connected to ground (immediate damage).

5. Never remove the alternator unless the battery is disconnected from the circuit.

6. When installing the battery, make sure the negative terminal is connected to ground.

7. Never use a voltage indicator connected directly to the household mains (110 or 220 V). Use only a 12 V indicator.

8. Do not test diodes by applying voltage above 12 V or with a megohmmeter, as its test voltage is too high for the diodes and they will be punctured (short circuit). When testing wiring insulation with a megohmmeter, disconnect all wires from the alternator.

9. If the battery is charged while installed in the vehicle, both battery cables must be disconnected. Connect the positive charger clamp to the positive battery terminal, and the negative charger clamp to the negative battery terminal.

10. Disconnect all wires from the alternator and from the battery before electric welding of any body parts.

11. Check the wiring and connections of the electrical system and rectify faults with the engine stopped and the battery disconnected.

12. Incorrect connection of the wires will destroy the rectifier and voltage regulator.