Power Supply Function
• The amplitude of load dump is determined by the rotational speed of alterna-
tor and the strength of magnetic field in the case of disconnection of the
battery.
• The pulse duration of load dump is mainly determined by the time constant
and pulse amplitude of the excitation circuit.
Inside most novel alternator, the amplitude of load dump is decreased by in-
creasing the limiter diode (clamping diode). The load dump may be caused by
cable corrosion, poor cable contact or disconnecting the battery intentionly
when the engine is running.
The pulse shape and parameters for an alternator without centralized load
dump suppression (Test A) are given in follow.
• t: Time
• U: Test voltage
• t
d
: Duration of pulse
• t
r
: Rising Slope
• U
A
: Supply Voltage for generator in operation (see ISO 16750-1)
• U
S
: Peak voltage
Parameter
Type of system
Minimum test
requirements
12V 24V
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