ITech IT6512C User Manual page 55

Load dump dynamic behavior
This test is a simulation of load dump transient occurring in the event of a
discharged battery being disconnected while the alternator is generating
charging current with other loads remaining on the alternator circuit at this
moment.


Inside most novel alternator, the amplitude of load dump is decreased by
increasing 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 are given in follow.
Description:
t: time
U: test voltage
t : Duration of pulse
d
t : Rising Slope
r
U : Supply Voltage for generator in operation( see ISO 16750-1 )
A
U : supply Voltage
S
Parameter
U
display on the VFD.
Note
Please make sure the trigger source is selected in MANUAL item in above
operations(refer to step 8th). And user need to turn on the internal load to speed
up the falling time during ISO16750-2 waveform operations.
The amplitude of load dump is determined by the rotational speed of
alternator 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.
U =12V
N
a
(V) 79≤U
S S
(Ω)
a
R 0.5≤R
i
Copyright© Itech Electronics Co., Ltd.
TEST PULSE 5A & 5C
Type of system
U =24V
N
≤101 ≤202
151≤U
S
≤4 ≤8
1≤R
i i
Function and Features
Minimum test
requirements
10 pulses at 1 min
intervals
47