A test pulse is described by a curve which is characterized by specific parameters. The shape of the curve depends on the vehicle network voltage.
Representation example for test pulses for a 12 V vehicle network (according to DIN 40839 part 1)
Significance of parameters:
t1: Interval between pulses
t2: Duration of single interference
t3: Recovery time, duration between end of interference and beginning of interference
t4: Duration of switching burst
t5: Recovery time
t6: Duration of peak voltage drop Us
t7: Rise time from Us to Ua
t8: Duration of Ua
tf: Rise time operation voltage
tr: Pulse rise time
td: Duration of pulse
Ua: Voltage drop after transient state with reference to test voltage Up
Not all given parameters are used for the description of a test pulse.
Further user-defined or in-house standard specific test pulses can be given.
Definition of the severity level
The severity level determines the peak voltage Us of the test pulse.
According to
DIN 40 839-1the following severity levels are defined:
Determination of severity levels for test pulses by means of pulse amplitudes according to DIN 40839 part 1
Test pulse
|
Pulse amplitude U s in volts
at severity level
(for vehicle network voltage of 12/24V)
|
|
I
|
II
|
III
|
IV
|
1
|
-25/-50
|
- 50/-100
|
- 75/-150
|
-100/-200
|
2
|
+ 25
|
+ 50
|
+ 75
|
+ 100
|
3a
|
-25/-35
|
-50/-70
|
-100/-140
|
-150/-200
|
3b
|
+25/35
|
+50/70
|
+75/140
|
+100/200
|
4
|
-4/-5
|
-5/-10
|
-6/-14
|
-7/-16
|
5
|
+26,5/70
|
+46,5/113
|
+66,5/156
|
+86,5/200
|
The peak voltage depends on the severity level and on the vehicle network voltage. Further user-defined or in-house standard specific severity levels with corresponding voltages U s can be defined for given test pulses.