Attention! When working with the generator, observe the following requirements:
- do not remove the battery, generator and voltage regulator with the ignition key inserted;
- mark the wires to avoid confusing them during installation;
- do not remove the generator when installed (connected) AB;
- turn off the battery during welding.
Alternator model used on BMW series car «x5» with body «E53», depends on its engine configuration. All generators are three-phase alternating current with a built-in rectifier unit with nine valves (six main rectifier diodes and three additional), rated output current from 75 A or 150 A and an electronic voltage regulator with an adjustment range of 13.5–14.1 V. The design features of the generator and its power depend on the engine model (pic. 16.2).
The generator drive is carried out from the crankshaft using a belt. In this case, the rotor with the excitation winding rotates inside the stationary stator winding. By means of carbon brushes and slip rings, the excitation current passes through the field winding. This creates a magnetic field. The magnetic field constantly changes its position relative to the stator winding in accordance with the speed of rotation of the rotor. Two slip rings are pressed onto the rotor shaft. The generator is cooled through the openings of the covers, the air is supplied by a blade fan mounted on the drive pulley, or it is liquid-cooled («M57» And «M62»). The frequency of rotation of the generator rotor is twice the frequency of rotation of the crankshaft of the engine. However, since the battery is charged only with direct current, the generator has a built-in rectifier and voltage regulator.
The generators are equipped with electronic voltage regulators of type 5 RK 1815 or 5K 1592 with an output voltage of about 14.3 V. The voltage regulator changes the charging current by turning the excitation current on / off, in accordance with the state of charge of the battery.
Start of charging current supply to AB («M54») is carried out at a voltage of 14 V at the outputs and a steady state - 1000 min-1. The charging current of the generator, with a voltage of 14 V at its terminals and a rotational speed of the rotor shaft, is:
- at 1400 min-1 -20 A;
- at 2100 min-1 - 50 A;
- at 6000 min-1