GB/T 3483-1983 Guidelines for lightning tests on electronic equipment
Some standard content:
National Standard of the People's Republic of China
Guidance for lightning test for electronic equipmentsUDC621.3
GB3483-83
This guideline mainly explains the mechanism of lightning strikes on electronic equipment, the characteristics of lightning impulse waves and the principle of lightning test, so that personnel engaged in the compilation of electronic equipment standards, product design, manufacturing and inspection can formulate and select corresponding standards based on GB3482-83 "Lightning Test Methods for Electronic Equipment". This document provides the principles for reasonably solving relevant test problems to ensure that the test results have good simulation and reproducibility. This guideline is applicable to lightning simulation tests of electronic equipment with solid components connected to external lines. It is not applicable to the inspection of lightning direct strike equipment and electromagnetic interference caused by lightning.
1 Terminology
1.1 Lightning impulse full wave
A non-periodic transient voltage wave. It usually rises to a peak value very quickly and then drops to zero more slowly. Sometimes other shock waves such as attenuated oscillation shock waves may be used for special purposes. 1.2 Dielectric breakdown
refers to the phenomenon of loss of dielectric strength of solid, liquid, gaseous medium and their combination under the action of high voltage. When the dielectric breaks down, the voltage between the electrodes drops rapidly to zero or close to zero. 1.2.1 Flashover
Dielectric breakdown along the insulating surface in gas or liquid medium. 1.2.2 Discharge
Dielectric breakdown in liquid or gas medium. 1.2.3 Breakdown
The phenomenon of loss of dielectric strength of solid medium under the action of high voltage. In solid medium, dielectric breakdown is permanent, while in liquid and gas medium, dielectric breakdown is sometimes temporary. 1.3 Breakdown discharge voltage
For breakdown after the peak of the shock wave, the breakdown discharge voltage value refers to the peak value of the test voltage that causes the breakdown discharge. For the breakdown before the peak of the shock wave (wave front), the breakdown discharge voltage value refers to the instantaneous voltage value that causes the breakdown discharge. The breakdown discharge voltage value varies randomly, so it is necessary to undergo multiple tests to obtain the breakdown discharge voltage value according to the statistical method. 2 Overview of Lightning Strike Electronic Equipment
2.1 Paths of Lightning Strike Electronic Equipment and Lightning Overvoltage The paths of lightning strike electronic equipment can be divided into two situations. The first is the lightning impulse traveling wave, which invades the equipment through the outdoor information transmission lines, the connecting lines between equipment, and the power incoming lines, causing damage to the electronic equipment connected in series in the middle or at the end of the line. The second is lightning strikes the earth or the grounding body, causing the ground potential to rise, affecting nearby electronic equipment, generating a counterattack on the equipment, and damaging its insulation to the ground. The lightning overvoltage applied to the electronic equipment by lightning shock waves invading from different paths is divided into longitudinal overvoltage and transverse overvoltage. The overvoltage to the ground that appears at a certain point in the balanced circuit is called longitudinal overvoltage. The counterattack caused by the rise in ground potential can be regarded as a longitudinal overvoltage invading from the ground system. The overvoltage between balanced circuit lines or unbalanced circuit lines to the ground is called transverse overvoltage. Equipment connected to symmetrical balanced transmission lines will generate transverse overvoltage due to the imbalance of longitudinal overvoltage between the two lines of the line to the ground, or due to the difference in the action time of the longitudinal protection element. For electronic equipment connected to the coaxial cable system, the longitudinal overvoltage is the transverse overvoltage. Lightning impulse overvoltage can cause insulation breakdown of equipment; impulse overcurrent can damage components of electronic equipment. The purpose of conducting longitudinal lightning tests is to test the insulation strength of components to the ground (casing) of the equipment under the action of longitudinal overvoltage. The purpose of transverse lightning tests is to test the ability of electronic equipment to withstand lightning impulses. 2.2 Damage Mechanism of Electronic Equipment
The damage of longitudinal impact to the components of the balanced circuit of the equipment includes: damage to the components or their insulating media connected between the line and the ground, breakdown of the insulation between the turns, layers or lines of the transformer that plays the role of impedance matching between the line and the equipment, etc. The transverse impact can be transmitted in the circuit like information, damaging the capacitance, inductance and solid components with poor impact resistance of the internal circuit. The degree of damage to the components in the equipment by lightning depends on the insulation level of the components and the intensity of the impact. For insulation with self-recovery ability, the breakdown is only temporary. Once the impact disappears, the insulation will be restored quickly. For some non-self-recovery insulating media, if only a small current flows through it after the breakdown, the operation of the equipment will not be interrupted immediately. However, as time goes by, the insulation of the components will gradually decrease due to moisture, and the circuit characteristics will deteriorate, and finally the circuit will be interrupted. Some components, such as the collector and emitter or the emitter and base of the transistor, will be permanently damaged if reverse breakdown occurs. For components that are susceptible to energy damage, the degree of damage mainly depends on the current flowing through them and the duration.
Generally speaking, the waveform of the lightning test for equipment is to select an impulse voltage wave with a certain energy. Therefore, the impulse wave used for the test should not only have a certain voltage amplitude, but also have an impulse wave energy as close to the actual value as possible. This makes the test both an impulse withstand voltage test and a certain impulse current test.
3 Lightning impulse waveform
Over the years, many observations have been conducted at home and abroad on lightning impulse waves entering electronic equipment along different line structures, and a large amount of observation data has been obtained.
Generally speaking, the impulse voltage peak value applied to electronic equipment is determined by the insulation level of the line. In front of electronic equipment, there are generally security devices, and their limiting voltage determines the impulse voltage peak value that may appear on the electronic equipment. The lightning impulse wave that strikes the equipment along the overhead communication line is almost an oscillating waveform. The lightning impulse wave that strikes the equipment along the underground cable is mostly a double exponential wave with a long duration and approximately a single polarity. The counter-attack wave generated by the lightning directly striking the grounded object to increase its potential is mostly a single polarity wave with a short duration. 3.1 Unipolar impulse voltage full liquid
According to the analysis: the spectrum of negative or positive unipolar impulse waves is extremely wide. But the energy of the impulse is mainly concentrated in the low-frequency range. For example, 1.2/50μs impulse wave, about 90% of the total energy is distributed below the frequency of 18kHz. 10/700μs impulse wave, more than 95% of the total energy is distributed below the frequency of 3kHz. It can be seen that this type of waveform is the most harmful to electronic equipment working in low-frequency or DC state. Figure 1 is the accumulation distribution diagram of the impulse energy of the two waveforms. 100
10/700ms
Figure 1 Accumulation distribution of impulse energy
18 frequency kHz
3.2 Attenuated oscillation shock wave
GB3483-83
The results of observations on the access line of overhead communication lines in my country show that 98.6% of the lightning impulses that strike people are oscillations, and the fundamental frequency is mostly in the range of 3.3 to 17kHz. The attenuated oscillation shock wave is more harmful to the high-frequency branch in the analog communication equipment with frequency division, because in this type of communication mode, the attenuated oscillation shock wave can enter the internal circuit with little attenuation and break down the more fragile solid components. 3.3 Waveform selection principle
The purpose of the simulation test is to reproduce the lightning strike of the electronic equipment in the test room through certain methods, so as to improve the lightning protection measures and make the equipment obtain satisfactory operating reliability. When formulating professional standards, it is necessary to select appropriate test parameters according to the path, nature and polarity of the lightning impulse that may strike the equipment. 3.3.1 Severity level of the test
The severity level of the test is met by selecting the waveform and peak value of the test voltage. If the lightning strike environment conditions of the electronic equipment are known, the severity level of the test should be determined based on the actual situation and the reliability required by the system. For equipment in areas with strong lightning activity and high reliability requirements, a more severe test level should be selected. 3.3.2 Peak value of impulse voltage
The peak value of impulse voltage is one of the important parameters representing the severity level. When the test waveform is determined, the high peak voltage shock wave is more severe than the low peak voltage shock wave. In this case, the steepness of the shock wave increases, and the peak value of the cutoff wave formed by the action of the protection device also increases. It poses a greater threat to the inductive components in the equipment.
3.3.3 Shock wave front time
The wave front time should be selected comprehensively based on the environmental conditions of the electronic equipment, the feasibility of the shock wave generator circuit and the purpose of the test. According to on-site observations (tested at the transmission line terminal). The wave front time is generally distributed between a few microseconds and hundreds of microseconds, depending on the transmission line. Generally speaking, the wave front time of the open line is shorter, and the wave front time of the underground cable and the conductor with the rail is longer. Under the same peak value, the shorter wave front time corresponds to an increase in steepness, which is more severe for the test sample. 3.3.4 Shock wave half-peak time
The length of the half-peak time indicates the size of the shock wave energy. The longer the half-peak time, the greater the energy. The half-peak time of the shock wave of different transmission lines can be distributed between tens of microseconds and several milliseconds. 3.4 Recommended waveform
When assessing the lightning resistance performance of equipment due to direct lightning strikes through grounding devices, 1.2/50μs waves can be used. When electronic equipment is led out (introduced) from overhead open wires, it is recommended to use a 4/300μs shock wave test. However, considering that some domestic dischargers have not yet reached the indicator of impulse discharge voltage below 1kV recommended by relevant international standards, equipment using such discharge tubes for protection must be tested with a full wave of a higher critical impulse discharge voltage. At this time, it is temporarily allowed to shorten the half-peak time of the shock wave. For example, when a discharge tube with a critical impulse discharge voltage of 1300V is used, the test waveform should be 4/200us. For some electronic equipment led (out) by open wires (including double wires), each professional standard should also determine whether to conduct an attenuated oscillation shock wave test based on its standard characteristics. If a test is required, the oscillation frequency of the test waveform and other test parameters should be determined. When the equipment is introduced by cable, 10/700μs wave or full wave with longer half-beep time can be used for testing, and it is not necessary to carry out attenuated oscillation shock wave test.
When the electronic equipment is connected to the rail or similar conductor, it is proved according to practical experience that the short wave test of 1.2/50us cannot meet the requirements, so it is temporarily recommended to use the long wave of 10/200μs. 4 Waveform generation
The circuit design of the shock wave generator should take into account the ease of production of the equipment and have a certain flexibility when some waveform parameters must be modified for some needs. The generated waveform should meet the relevant provisions of GB3482-83. In addition, the determination of the parameters of each component in the generator must also take into account that the load should not have a significant impact on the waveform, and the short-circuit current should be able to meet the test requirements. GB3482-83 gives three types of generator circuits, which can be selected according to the equipment application conditions and test purposes. 4.1 Unipolar shock wave generator circuit
4.1.1 The basic impulse voltage generator circuit can be used. Since the test voltage of electronic equipment is not high, a single-stage generator should be used as much as possible to obtain high efficiency and simplify the equipment. The commonly used circuit is shown in Figure 2. It is suitable for impact tests of test samples with high input impedance. R2
The unipolar shock wave is obtained by discharging the charged capacitor C to the RC circuit. The main capacitor C, charges the wavefront capacitor C2 through the wavefront resistor R?, and the voltage rise curve of C2 is the wavefront of the shock wave. The process of C1 and C2 discharging to the wave tail resistor R together forms the half-peak time of the shock wave. Therefore, the wavefront time is mainly determined by R2 and C2, while C1 and R1 determine the half-peak time of the shock wave. When C,When R, there is the following simple relationship: Ti~2.3C,R2
T2~0.7C,R
Where: T,——the apparent wavefront time of the shock wave, T2—
——the apparent half-peak time of the shock wave.
C's charging voltage and R also determine the energy of the test wave and the short-circuit current flowing through the test sample. Usually, in order to reduce the impact of the load on the test waveform, C, and R, can be appropriately increased and reduced. The anti-vibration resistor R3 is usually a few ohms, which is used to prevent the vibration that may be caused when the test sample is connected. All resistors are non-inductive resistors.
Table 1 shows the typical wave parameters for testing open-wire equipment (the input and output ends are protected by air gap dischargers, and they should be able to discharge in the following tests.
Project name
Waveform (μus)
Electricity (C)
Charging voltage of capacitor C (kV)
Short-circuit current (A)
Main capacitor C, (μF)
Front-wave capacitor C (μF)
Tail resistance R, (Q)
Front-wave resistance R2 (Q)
Anti-vibration resistance R (S)
Table 2 shows the typical wave parameters for testing cable equipment (the input and output ends are protected by air gap dischargers, and they should be able to discharge in the following tests).Project name
Waveform (μs)|| tt||Electricity (C)
Capacitance C, charging voltage (kV)
Short-circuit current (A)
Main capacitor C (μF)
Wavefront capacitor C2 (μF)
Wavetail resistor R, (2)
Wavefront resistor R2 (Q)
Anti-alarm resistor R (2)
GB3483--83
Coaxial cable parameters
10/700
Symmetrical cable parameters
10/700
4.1.2 When the test sample with low input impedance adopts Figure 2, it will be difficult to modulate the wave. Therefore, it is recommended to use the circuit of Figure 3. The circuit of Figure 3 (a) is actually in the over-damping state. The main capacitor C, the modulating inductor L1, a current generator composed of a resistor (R+R,). The test waveform is extracted from the wave tail resistor R,. All resistors are non-inductive resistors. By changing the values of CI, L, (R+R,), different impulse voltage waveforms can be obtained.
When the ratio of the apparent half-peak time T, to the apparent wavefront time T, is greater than 10, the following simple relationship exists: T2
R+R,~1.5-
Table 3 is a typical wave parameter for testing low input impedance equipment for connecting rails. Table 3
Waveform (μs)
Modulating inductance L, (μH)
Damping resistor R (Q)
Wave tail resistor R, ()
Main capacitor C (μF)
10/200
G B3483--83
Figure 3 (b) is also the basic circuit of the impulse voltage generator, and its principle is the same as that of 4.1.1. C
4.2 Attenuated oscillation shock wave generator circuit
The formation of the attenuated oscillation shock wave can be formed by using the R, L, C oscillation circuit, and its waveform is a single-frequency oscillation, and the oscillation frequency is: f=
It can also be generated by a single-polarity shock wave through a high-pass filter. As shown in Figure 4. The attenuated oscillation shock wave waveform generated is actually the sum of all high-frequency components in the single-polarity shock wave with a frequency above the filter cutoff frequency. It is particularly suitable for high-pass filter branches with the same cutoff frequency, and the equipment under test such as carrier machines must be tested for attenuated oscillation shock wave tests. At this time, it can provide shock waves close to the actual situation. When the high-pass filter is designed as a fixed K-type high-pass as shown in Figure 5, the lowest frequency contained in the oscillation shock wave is the cut-off frequency of the filter:
High-pass filter
Figure 4 and Table 4 are recommended for testing electronic equipment that has not yet mastered the lightning parameters of the system but must perform attenuated oscillation shock wave tests. www.bzxz.net
Lower limit of working frequency band (k.Hz)
Oscillation frequency (kHz)
Charging voltage of main capacitor C (kV)
Main capacitor C (μF)
Wavetail resistance R, ()
Wavefront resistance R, (9)
Wavefront capacitance C2 (μF)
Filter capacitance C
Filter inductance L (mH)
5 Test procedure
5.1 Terminal
GB3483-83
2000PF
2000pF
The response of some solid electronic equipment to the impact of shock waves is closely related to the load conditions. In order to reduce the measurement illusion caused by reflection, for test samples with multiple output and input terminals, except for the terminals where the shock is applied, the rest should be terminated according to the load impedance of normal working state during the test.
5.2 Light shielding
When the air gap discharger is exposed to light, the impulse discharge voltage is relatively stable, the dispersion is small, and the impulse discharge voltage is low. If there is no light, the impulse discharge voltage is high and the impulse discharge characteristics are poor. This phenomenon is particularly prominent when the characteristics of the air gap discharger are poor. Figure 6 is a schematic diagram of the volt-second characteristic curve of the same glass discharge tube under light and light shielding conditions. Light shielding
During operation, electronic equipment is generally in a state of not seeing light. Except for the product designed to operate in light, the test should be carried out in a more severe light shielding state.
5.3 Debugging of shock wave generator
GB3483—83
Because the waveform generated by the generator is closely related to the structure and layout of the generator, although there are simplified calculation formulas for the circuit parameters of the design of the impulse generator, the problem cannot be solved by calculation alone. The circuit must also be debugged to obtain the required waveform. During debugging, the measured waveform should be taken as the standard, and the circuit components should be adjusted according to the estimation formulas in 4.1 to 4.2 until the waveform meets the predetermined requirements. 5.4 Critical impulse discharge voltage full wave test
For equipment using air gap dischargers such as discharge tubes for protection, especially those working in DC and low frequency, the critical impulse discharge voltage can provide a large energy lightning impulse test for the internal circuit, which is an important and mandatory test item. The critical impulse discharge voltage value of the air gap discharger is determined by testing at a steepness of 1kV/us.
GB348283 stipulates the critical impulse discharge voltage impulse full wave test, the purpose of which is to test the impact resistance of the test sample to the unipolar full wave impact when the air gap discharger is not in action. When doing this test, the corresponding protective components should be removed. 5.5 Measurement
The purpose of the impulse measurement is to check the response of the equipment to the impulse wave, measure the current flowing through each protection component, verify the coordination of each protection level and the protection effect, etc.
High-voltage measuring instruments should be used during measurement, and they should meet the relevant requirements of high-voltage measurement technology. Try to shorten the measurement lead to improve the accuracy of the test system. For electronic equipment with "inland" and "outside", it is not possible to use an asymmetric measurement system with shell grounding to directly measure. Additional Notes:
This standard was drafted by Guangdong Post and Telecommunications Research Institute and the Communication Signal Research Institute of the Ministry of Railways Research Institute.
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