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GB/T 21437.2-2008 PDF in English

GB/T 21437.2-2008 (GB/T21437.2-2008, GBT 21437.2-2008, GBT21437.2-2008)
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GB/T 21437.2-2008: PDF in English (GBT 21437.2-2008)

GB/T 21437.2-2008
Road vehicles. Electrical disturbances from conduction and coupling. Part 2. Electrical transient conducting along supply lines only
ICS 43.040.10
National Standards of People's Republic of China
GB/T 21437.2-2008/ISO 7637-2.2004
Electric disturbance caused by conduction and coupling of road vehicles
Part 2. Electrical Transient Conduction Along Power Lines
(ISO 7637-2.2004, IDT)
Posted on.2008-02-15
2008-09-01 Implementation
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
China National Standardization Administration released
Preface III
1 Range 1
2 Normative references 1
3 Terms and Definitions 1
4 Test Procedure 1
5 Test Equipment and Requirements 4
Appendix A (Normative) Functional Failure Mode Severity Classification 13
Appendix B (Informative) General Techniques for Improving Equipment Electromagnetic Compatibility 17
Appendix C (Normative) Transient Emission Evaluation - Voltage Waveform 18
Appendix D (Normative) Test Pulse Generator Verification Procedure 21
Appendix E (informative annex) Determination of pulse generator energy capacity 23
Appendix F (informative) Sources of transients in road vehicle electrical systems 26
GB/T 21437.2-2008/ISO 7637-2.2004
GB/T 21437 “Electrical disturbance caused by conduction and coupling of road vehicles” consists of three parts.
--- Part 1. Definitions and general descriptions;
--- Part 2. Electrical transient conduction along the power line;
--- Part 3. Electrical transients coupled by capacitive and inductive coupling of wires other than power lines.
This part is the second part of GB/T 21437, which is equivalent to ISO 7637-2.2004 "Road vehicles caused by conduction and coupling.
Electrical disturbances Part 2. Conduction of electrical transients along power lines.
The editorial modification is. In Table 1, the UA and UB are annotated.
Appendix A, Appendix C and Appendix D of this part are normative appendices, appendix B, appendix E and appendix F are informative appendices.
This section is proposed by the National Development and Reform Commission.
This part is under the jurisdiction of the National Automobile Standardization Technical Committee.
This section drafted by. China Automotive Technology and Research Center.
Participated in the drafting of this section. Shanghai Volkswagen Automotive Co., Ltd., Ministry of Information Industry Telecommunications Transmission Institute, Changsha Automobile Electrical Research Institute.
The main drafters of this section. Xu Li, Liu Xin, Liu Xinliang, Zou Dongxi, Hu Mengxi, Lin Yanping.
GB/T 21437.2-2008/ISO 7637-2.2004
Electric disturbance caused by conduction and coupling of road vehicles
Part 2. Electrical Transient Conduction Along Power Lines
1 range
This section specifies the transmission of equipment on commercial vehicles installed in light commercial vehicles or 24V electrical systems for passenger cars and 12V electrical systems.
Bench tests for conducting transient electromagnetic compatibility tests include transient injection and measurement. This section also specifies the transient immunity failure mode
Severity classification.
This section applies to road vehicles of various power systems (such as spark ignition engines or diesel engines, or motors).
2 Normative references
The clauses in the following documents have been adopted as references in this part of GB/T 21437. Any quoted text
Each of its subsequent amendments (not including errata content) or revisions does not apply to this section. However, it is encouraged to reach agreements based on this section
The parties to the meeting studied whether the latest versions of these documents could be used. The most recent version of any referenced document that is not dated applies to this section.
GB/T 21437.1 Electrical disturbances caused by conduction and coupling on road vehicles Part 1. Definitions and general description
(GB/T 21437.1-2008, ISO 7637-1.2002, IDT);
3 Terms and Definitions
The terms and definitions established in GB/T 21437.1 apply to this section.
4 Test procedures
4.1 General requirements
The transient immunity test of the power line and the transient immunity test of the device involved in this part are all “bench test” in the test room.
get on. Some test methods require the use of artificial networks, providing comparable test results between laboratories. These methods can also be made
The basis for the development of the device and system, and can be used during the production phase (see Appendix B).
A bench test to evaluate the transient immunity of the device's power line can be performed using a test pulse generator, but this method does not
Cover all the various transients that may occur on the vehicle. The test pulse described in 5.6 is typical of a typical pulse. In special circumstances,
Additional test pulses. If a device is not affected by similar transients in the vehicle due to its function or connection status, some pulses can be ignored.
Vehicle manufacturers can define test pulses for specific devices.
Unless otherwise specified, the allowable error of the variable is ±10%.
4.2 Test temperature and test voltage
During the test, the ambient temperature should be 23 °C ± 5 °C. The test voltage shall comply with the provisions of Table 1. If this part of the content user
The consensus on the adoption of other values should be noted in the test report.
Table 1 Test voltage
Test voltage 12V system/V 24V system/V
UA 13.5±0.5 27±1
UB 12±0.2 24±0.4
Note 1. The test voltage when the UA is operating as a generator.
Note 2. UB is the test voltage when the battery is powered.
GB/T 21437.2-2008/ISO 7637-2.2004
4.3 Voltage Transient Emission Test
Tests for the Transient Conducted Emission of Automotive Electrical and Electronic Components of the DUT (Device Under Test) along the Battery Supply Line or the Switching Power Supply Line
Evaluation procedure, the DUT is a potential source of conducted disturbances, and the measurement arrangement must not be disturbed by the surrounding electromagnetic environment.
To regulate the load impedance of the DUT, an artificial network should be used to measure voltage transients from the disturbance source DUT (see 5.1). Sources of harassment
The artificial network is connected to a shunt resistor Rs (see 5.2), a switch S (see 5.3) and a power supply (see 5.4). As shown in Figure 1a) or Figure 1b). people
The unit is mm
a) Slow pulses (millisecond range or slower)
b) fast pulses (nanosecond to microsecond range)
1---oscilloscope or equivalent equipment;
2 --- voltage probe;
3 --- artificial network;
4---DUT (transient source);
5 --- ground plate;
7---ground wire; length less than 100mm.
Points A, B, and P are shown in Fig. 3.
Figure 1 Transient emission test layout
GB/T 21437.2-2008/ISO 7637-2.2004
All connection wiring between the industrial network, switch and DUT should be placed 50+10 0 mm above the metal ground plane. Cable length should follow
The actual use of the vehicle is selected, ie, the wiring should be able to withstand the operating current of the DUT, and after the vehicle manufacturer and supplier agree
If not specified in the test plan, the DUT shall be placed on a non-conductive material (material thickness 50+10 0 mm) above the ground plate.
When using a voltage probe (see 5.5.2) and an oscilloscope (see 5.5.1) or a waveform acquisition device (see 5.5.3) to measure the disturbance voltage,
Can be near the DUT's terminals [see Figure 1a) or Figure 1b)]. Repetitive transients should be measured when switch S is closed. If the transient is a power source
For disconnection, the measurement should be made when switch S is open. See Appendix C for evaluations and various values.
The DUT should be measured in open, closed, and various operating modes. The DUT should accurately work on the test meter
Specified in a row. Select the sampling rate and trigger level to obtain a waveform that shows the full transient width, with a sufficiently high resolution
Rate to show the maximum positive and negative parts of the transient. The DUT should be operated according to the test plan using the appropriate sampling rate and trigger level and recorded
Voltage amplitude. Other transient parameters such as rise time, fall time, and transient width should also be recorded. Unless otherwise specified,
Requires acquisition of 10 waveforms. Record the waveform that contains the largest positive amplitude and the largest negative amplitude (and the parameters associated with it).
According to Appendix C, evaluate the measured transients. All relevant information and test results should be recorded. If a test plan is required, it should include
Transient evaluation results related to the performance specifications specified in the test plan.
4.4 Transient Immunity Test
Transient immunity test of electrical/electronic devices shall be arranged according to Figure 2. For test pulses 3a and 3b, test pulse generator side
The wire between the port and the DUT should be placed parallel to the ground plane 50 + 10 0 mm above the length of 0.5m ± 0.1m.
With the DUT and resistor Rv disconnected, adjust the test pulse generator (see 5.6) to generate a specific pulse polarity, amplitude, width
Degrees and impedance. Select the appropriate value from Appendix A. Then connect the DUT to the pulse generator [see Figure 2b)] and disconnect the display
Wave device.
According to the actual situation, the function of the DUT can be evaluated during and/or after the application of the test pulse.
In order to accurately generate the required test pulse, the power supply needs to be turned on and off. If the test pulse generator comes with power, this conversion
The process can be completed by a test pulse generator.
One of the ways to simulate the waveform of an alternator with concentrated load dump suppression (see Figure 12) is to incorporate a suppression diode (or diode)
The bridge) is connected to the output terminals of the test pulse generator [see Figures 2a and 2b)]. Since individual diodes generally vary, there is
Can not withstand the large current generator, it is recommended to use a diode bridge layout [Figure 2c) example]. Use the same for test pulses 5a and 5b
Kind of pulse generator.
a) Pulse adjustment
Figure 2 Transient immunity test device
GB/T 21437.2-2008/ISO 7637-2.2004
b) Pulse injection c) Example of suppression diode bridge only for test pulse 5b
1---oscilloscope or equivalent equipment;
2 --- voltage probe;
3 --- test pulse generator with internal resistance Ri;
5 --- ground plate;
6---ground line (maximum length of test pulse 3 is 100mm);
7---Resistance Rva;
8 --- Diode Bridge b.
a Load dump test pulses 5a and 5b for simulating vehicle system loads. When Rv is used, its size should be specified in the test plan (typical values are 0.7Ω
Between 40Ω).
b Used to simulate a pulse 5b of an alternator dump waveform with concentrated load dump suppression [see Figure 2c)].
c Increase the forward biased diode to achieve the maximum open circuit (suppression) voltage.
Figure 2 (continued)
Suppression diodes and suppression voltage levels (clamping voltages) used by different automotive manufacturers are non-standard, suppliers (component manufacturing
The manufacturer must obtain the diode and clamp voltage specification information from the manufacturer to complete the test. On the diode bridge, you need to add more
A single diode to provide a specific clamping voltage.
5 Test Equipment and Requirements
5.1 Artificial Network
Artificial networks replace the impedance of vehicle wiring harnesses and are used as reference standards in laboratories to determine the performance of equipment and electrical and electronic devices.
Figure 3 is a schematic diagram of a manual network.
Artificial networks should be able to withstand continuous loads consistent with DUT requirements.
Figure 4 shows the measured impedance between the P and B terminals when the A and B terminals are short-circuited in the case of an ideal electrical component |ZPB|
The value varies with frequency. In fact, the impedance of an artificial network should not deviate from the curve shown in Figure 4 by more than 10%.
If the artificial network has a metal shell, it should be placed flat on the ground plane. The ground of the power supply should be connected with the grounding plate, as shown in Figure 1a) and
1b) shows.
GB/T 21437.2-2008/ISO 7637-2.2004
A---power end;
B---common (can be grounded);
P---DUT end;
R--- resistance.
The main features of various components.
L = 5μH (air core coil);
Internal resistance between P and A. < 5mΩ;
C = 0.1μF at.200V AC operating voltage and 1500V DC operating voltage;
Figure 3 Artificial network
5.2 Parallel Resistor R
The shunt resistor Rs (see Figure 1) is used to simulate the DC resistance of other electrical devices of the vehicle in parallel with the DUT. These electrical devices
The connection of the DUT is not controlled by the ignition switch. The selected Rs corresponds to the wiring harness between the disconnected ignition switch terminal and ground when the switch is opened.
The measured resistance should be determined by the vehicle manufacturer. Rs=40Ω should be used when there is no specific value. If you use wire wound
The resistance should be a double-wound resistor (ie, have a minimum reactance component).
In order to simulate the worst condition, Rs can be disconnected.
|ZPB|---Impedance in ohms (Ω);
Fig. 4 Impedance of frequency from 100犽H狕 to 100狕M狕|ZPB| as a function of frequency (short-circuit between terminal A and terminal B)
GB/T 21437.2-2008/ISO 7637-2.2004
5.3 Switch S
According to practical application, as shown in FIG. 1, the switch device S can be installed on any side of the artificial network. To measure fast transients
During the test, only one of the switching devices shown in FIG. 1 is actuated (contacts of the other switching devices should be closed). Before the test, it should be
The selected switchgear is stated in the test plan and written into the test report.
Since the switch S largely affects the transient disturbance characteristics, the recommended switching device is described as follows.
a) For high-voltage transients (above 400V), the recommended switchgear for standard DUT-equipped vehicles
switch. If no such device is available, car relays with the following characteristics should be used.
--- Contact current rating I = 30A, continuous resistive load;
--- High-purity silver contact material;
--- Relay contact without suppression;
--- Single/double (position) contacts insulated from the coil circuit;
--- coil with transient suppression.
When the contact is significantly degraded, the switch relay should be replaced.
b) For accurate evaluation of harassment, only switches with reproducible characteristics should be used. Electronic switches are recommended and the extent of harassment may be
Above the traditional switch (starting arc), it should be taken into account when evaluating the test results. Electronic switch is especially suitable for control suppression
The use of the device. When measuring low voltage (with less than 400V amplitude) transients, for example, low voltage transients are transiently suppressed
Sources should use electronic switches that have the following characteristics.
--- At 25A, the highest voltage Umax = 400V;
--- At 25A, the voltage drop ΔU ≤ 1V;
--- Test voltage UA1 = 13.5V, UA2 = 27V;
---R=0.6Ω, L=50μH (1kHz);
--- Parallel resistance Rs = 10Ω, 20Ω, 40Ω and external connection resistance;
--- Triggers. Internal and External;
--- Voltage probe. 1.100.
The switch should have the ability to withstand short circuits.
According to 5.1 and Figures 3 and 4 should be able to achieve artificial network, it should also be able to disconnect it (50 Ω artificial network defined frequency to
5.4 Power Supply
The internal resistance Ri of the continuous power supply should be less than 0.01 Ω. For frequencies below 400Hz, the internal impedance of the continuous power supply should be Zi = Ri. lose
The change in output voltage between 0 load and maximum load (including inrush current) should not exceed 1V. It should recover its value within 100μs.
The largest 63%. The peak-to-peak value of the superimposed ripple voltage Ur should not exceed 0.2V and the minimum frequency should be 400Hz.
When using a standard power supply (with sufficient ampacity) to simulate a battery, the battery's low internal resistance should also be simulated. When using a battery, need
The charging power reaches the specified standard level (13.5V and 27V, respectively).
5.5 Measuring Instruments
5.5.1 Oscilloscope
It is best to use a digital oscilloscope (minimum single-stroke scan sampling frequency of 2GHz/s, bandwidth of 400MHz, and input sensitivity of at least
5mV/scale). If you do not have a digital oscilloscope, you can use an analog long afterglow synchronization oscilloscope that meets the following minimum requirements.
--- Bandwidth. From DC to at least 400MHz;
--- Recording speed. at least 100cm/μs;
--- Input sensitivity. at least 5mV/ scale.
GB/T 21437.2-2008/ISO 7637-2.2004
An oscilloscope photo recorder or any other suitable recording device can be used for recording.
5.5.2 Voltage Probe
The characteristics of the voltage probe are as follows.
--- Decay. 100/1;
---Maximum input voltage. at least 1kV;
--- Input impedance Z and capacitance C, as specified in Table 2;
--- Voltage probe cable length. 3m;
--- The maximum length of the voltage probe grounding wire. 0.13m.
The length of each line will affect the measurement results and should be indicated on the test report.
Table 2 Voltage Probe Parameters

1 >40 < 4
10 >4 < 4
100 >0.4 < 4
5.5.3 Waveform Acquisition Equipment
Instead of an oscilloscope, you can use a transient waveform device that can acquire fast rise times.
5.6 Test pulse generator for immunity test
The test pulse generator shall be able to generate open circuit test pulses of 5.6.1 to 5.6.5 when |Us| is at a maximum, Us should be in Table 3 to Table 9
Adjustable within limits. The peak voltage Us should be adjusted to the test level specified in Appendix A with an error of (+10 0 )%. Unless otherwise specified, timing
Test pulse generator error and performance verification procedures in Appendix D. Refer to Appendix A for recommended values for the evaluation of the device's immunity.
5.6.1 Test pulse 1
The transient phenomena generated when the analog power supply and the inductive load are disconnected are applicable to all kinds of DUTs used in vehicles
Contains direct parallel connections (see Appendix F). The pulse form is shown in Figure 5, and the corresponding parameters are shown in Table 3.
Figure 5 Test pulse 1
GB/T 21437.2-2008/ISO 7637-2.2004
Table 3 Test pulse 1 parameters
Parameter 12V System 24V System
Us -75V~-100V -450V~-600V
Ri 10Ω 50Ω
-1.5) μs
5.6.2 Test pulses 2 and 2
Pulse 2a simulates a transient phenomenon caused by sudden interruption of current in the device connected in parallel with the DUT due to the harness inductance (see Appendix F). pulse
The impulse 2b analog DC motor acts as a generator and the ignition switch is turned off (see Appendix F). The pulse form is shown in Figure 6 and Figure 7, respectively.
The parameters are shown in Table 4 and Table 5, respectively.
Figure 6 Test pulse 2
Table 4 Test pulse 2 parameters
Parameter 12V System 24V System
Us +37V~+50V
Ri 2Ω
GB/T 21437.2-2008/ISO 7637-2.2004
Figure 7 Test pulse 2
Table 5 Test pulse 2 parameters
Parameter 12V System 24V System
Us 10V 20V
Ri 0Ω~0.05Ω
5.6.3 Test pulses 3 and 3
Simulate transients caused by the switching process. The characteristics of these transient phenomena are affected by the distributed capacitance and distributed inductance of the wire harness (see
Appendix F). The test pulse patterns for 3a and 3b are shown in Figure 8 and Figure 9, respectively, and the parameters are shown in Table 6 and Table 7, respectively.
Figure 8 Test pulse 3
GB/T 21437.2-2008/ISO 7637-2.2004
Table 6 Test pulse 3 parameters
Parameter 12V System 24V System
Us -112V~-150V -150V~-200V
Ri 50Ω
Figure 9 Test pulse 3
Table 7 Test pulse 3 parameters
Parameter 12V System 24V System
Us +75V~+100V +150V~+200V
Ri 50Ω
5.6.4 Test Pulse 4
Test pulse 4 simulates the reduction of the supply voltage generated when the starter circuit of the internal combustion engine is energized, excluding the spike voltage at start-up (see
Appendix F). The pulse form and parameters are shown in Figure 10 and Table 8.
GB/T 21437.2-2008/ISO 7637-2.2004
Figure 10 Test pulse 4
Table 8 Test pulse 4 parameters
Parameter 12V System 24V System
Us -6V~-7V -12V~-16V
Ua -2.5V to -6V and |Ua|≤|Us| -5V to -12V and |Ua|≤|Us|
Ri 0Ω~0.02Ω
a Vehicle manufacturers and equipment suppliers should negotiate this value to meet the requirements of the application.
5.6.5 Test pulses 5 and 5
Simulation of load-bearing transients, that is, the simulation is at the same time when the battery is disconnected (in the loss state), the alternator is generating a charging current, and the
The transients generated when there are still other loads on the motor circuit; the magnitude of the load dump depends on the rotational speed and field of the generator when the battery is disconnected
Strong size. The width of the load dump pulse depends mainly on the time constant and pulse amplitude of the excitation circuit (see Appendix F). Most new exchanges
Inside the generator, the load-dump amplitude is suppressed (clamped) by the addition of a limiting diode. The possible causes of load shedding are. cable rot
Erosion, poor contact, or intentional disconnection of the battery when the engine is running.
The pulse form and parameters of the alternator with decentralized load dump suppression (pulse 5a) are shown in FIGS. 11 and 9 . With a concentrated throw
The pulse form and parameters of the alternator with load suppression (pulse 5b) are shown in Figure 12 and Table 10.
For exponentially distributed pulses, the decreasing part of the curve should theoretically be reduced to 0V, but it is actually only reduced to UA.
In the application of load dump, the basic considerations for the power performance of the generator are as follows.
a) In the case of load shedding, the internal resistance of the alternator depends mainly on the speed of the generator and the magnetizing current.
b) The internal resistance Ri of the load dump test pulse generator shall be calculated from the following relationship.
Ri = 10 × Unom × Nact 0.8 × Irated × 12000 min-1
In the formula.
Unom --- rated voltage of the generator;
GB/T 21437.2-2008/ISO 7637-2.2004
Irated--- the specified current at the alternator 6000 r/min (same as the value given by ISO 8854);
Nact - The actual speed of the alternator in revolutions per minute (r/min).
Figure 11 Test pulse 5犪
Table 9 Test pulse 5 parameters
Parameter 12V System 24V System
Us 65V~87V 123V~174V
Ri 0.5Ω~4Ω 1Ω~8Ω
a Unsuppressed waveform.
b suppressed waveform.
Figure 12 Test pulse 5犫
Table 10 Test pulse 5 parameters
Parameter 12V System 24V System
Us 65V~87V 123V~174V
Us regulated by customer
GB/T 21437.2-2008/ISO 7637-2.2004
Appendix A
(Normative Appendix)
Functional failure mode severity classification
A. 1 purpose
A classification method is provided, that is, applying the test conditions specified in this section and classifying the functional status of automotive electronic devices. The described process
Applicable only to the bench testing method for automotive electrical and electronic devices.
A. 2 General rules
Parts or systems should be tested under actual environmental conditions, such as a complete vehicle environment, to help ensure that the sensitive system is technically and economically
Optimize the design.
This appendix is not a product specification nor can it be used as a product specification. Use the concepts in this section and apply them strictly.
To achieve agreement between car manufacturers and equipment suppliers, it should be possible to develop a document describing the functional status requirements for a particular device. This appendix
It may be a statement that a particular device has achieved the desired performance under the influence of a prescribed disturbance transient (see A.7).
A. 3 Functional failure mode classification system basic elements
Describe the severity classification of general failure modes, the following three elements are essential.
a) Functional status classification. the device is exposed to the electromagnetic environment and after the working state;
b) Test pulses and methods. Standards for typical test pulses and test methods for DUTs (this information is included in this series of standards
In the body of this section);
c) Severity of the test pulse. The severity level of the basic pulse parameter is specified.
A. 4 functional status classification
The following classifications are used for the functional status of the assembly device or system.
Class A. The device or system can perform all of its predesigned functions during and after disturbances are applied.
Class B. Devices or systems can perform all of their predesigned functions during disturbances; however, there may be one or more indicators
Beyond the prescribed deviation. All functions automatically return to the normal operating range after stopping the disturbance. Storage function should maintain Class A
Category C. The device or system does not perform one or more of its pre-designed functions during the harassment, but after stopping the harassment
Can automatically return to normal operation.
Category D. The device or system does not perform one or more of its pre-designed functions during the period of harassment until the harassment ceases.
After that, it can automatically restore to the normal operating state through a simple "operation or use" reset action.
Class E. The device or system does not perform one or more of its pre-designed functions during and after the disturbance is applied, and if it does not repair or
Without replacing the device or system, its normal operation cannot be resumed.
Note. "Function" here refers to the function performed by the electrical/electronic system.
A. 5 Test pulse severity rating
The recommended minimum and maximum severity levels are given in Table A. 1 and Table A. Grade III and Grade IV in 2 are given. In car manufacturers and
When the equipment supplier agrees, the level can be negotiated and the value between the values given in the table or values can be selected as the test time. In the absence of
Where there are any specific values specified, Table A should be selected. 1 and Table A. 2 The values given in Level III and Level IV.
GB/T 21437.2-2008/ISO 7637-2.2004
Table A. 1 12 犞 system recommended test level
Pulse a
Selected test level b
Test Level Usc
The minimum number of pulses or
Test time f
Short pulse cycle time or
Pulse repetition time
Minimum Maximum
5000 pulses
5000 pulses
10 pulses
1 pulse
1 pulse
a The test pulse is as described in 5.6.
b Vehicle manufacturer and equipment supplier agreement value.
c The amplitude Us is the value determined for each test pulse in 5.6.
d Since the minimum number of test pulses is 1, no pulse cycle time is given. When multiple pulses are applied, a minimum delay of 1 min should be allowed between pulses
Late time.
e See 5.6.5c). The test level reflects the load dumped by the generator at rated speed. If centralized load dump protection is used, apply as shown in Figure 12.
Set the test pulse 5b and use the values in Table 10.
f Number of pulses or test time for durability testing.
g Level I and Level II are deleted because this level cannot ensure sufficient noise immunity in road vehicles.
Table A. 2 24 犞 system recommended test level
Pulse a
Selected test level b
Test grade, Usc
The minimum number of pulses or
Test time f
Short pulse cycle time or
Pulse repetition time
Minimum Maximum
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.