Load dump

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Under load dump refers to the emergence of a voltage spike on a motor vehicle alternator to load shedding . In English , the term can also generally refer to a load shedding, but mostly in connection with a generator.

Normally, the regulator of the alternator keeps the generator voltage constant when the load fluctuates by appropriately energizing the field winding. If the load is removed abruptly, it will take a short time for the excitation magnetic field to dissipate. During this time, the voltage rises sharply because the generator current becomes smaller than the load current more slowly.

This happens, for example, when the vehicle battery is empty, i.e. when it consumes a high charging current, and during which the battery line is disconnected.

This voltage spike can destroy the electronics in the car, which is why Z diodes are used to limit the voltage. For this purpose, the main current diodes of the alternator are designed as Z-diodes, so-called main current zener diodes . Main current diodes are diodes which are used to rectify the alternating current of an alternating or three-phase generator. B. only take over the rectification to supply the controller.

literature

  • Kai Borgeest: Electronics in vehicle technology . 2nd edition, Vieweg + Teubner Verlag, 2010, ISBN 3-8348-0548-3
  • Manfred Krüger: Fundamentals of automotive electronics: circuit technology . 2nd edition, Hanser Fachbuchverlag, 2008, ISBN 3-446-41428-2