Surge (shock) immunity test is to simulate the interference effect caused by lightning strike, but it should be pointed out that the surge immunity test to assess the EMC performance of equipment is different from the voltage test to assess the high voltage insulation capability of the equipment. The former merely simulates the effects of indirect lightning strikes (devices usually cannot bear direct lightning). The international standard for surge (shock) immunity test is IEC61000-4-5:2005. The corresponding national standard is GB/T17626.2:200X《Electromagnetic Compatibility Test and Measurement Technology Surge (Shock) Immunity Test》
The purpose of this standard is to establish a common benchmark for evaluating the performance of electrical and electronic equipment in the event of surge (shock). This standard provides a consistent test method for evaluating the immunity of equipment or systems to specified phenomena.
|Grade||Open Circuit Test Voltage（10%）|
|Common Mode||Differential Mode|
2. Test Configuration
1) Test Equipment
－Equipment under test（EUT）；
－Cable（Specified type and length）；
－Coupling decoupling network；
－Combined wave signal generator；
－Coupling network / protection device；
－When the test frequency is high (such as gas discharge tube coupling) and the shielding cable is tested, the metal grounding reference plate is required. Only the typical installation of EUT needs metal grounding reference plane and it is necessary to connect to the ground reference plane in the test.
2) Test Configuration of EUT Power Supply End
The surge of 1.2 / 50s is added to the EUT power supply through the capacitance-coupled network (see figs. 7, 8, 9 and 10). In order to avoid the adverse effects on the non-tested equipment supplied by the same power supply and to provide sufficient decoupling impedance for the surge wave, so as to add required surge to the tested cable, the decoupling network is needed.
If there is no other provision, the length of the power line between EUT and coupling / decoupling network should not exceed 2m. Only ports directly connected to AC and DC power systems are considered power ports.
3. Test Procedure
1) Laboratory reference condition
In order to minimize the impact of environmental parameters on the test results, the test should be conducted under the climatic and electromagnetic environmental baseline conditions specified in 8.1.1 and 8.1.2.
2) Climatic Conditions
Unless otherwise specified in general standards, industry standards and product standards, the laboratory climate conditions shall be within the scope of the normal operation of the instruments specified by the respective manufacturers of the EUT and the test instruments.
Tests should not be conducted if the relative humidity is so high that condensation occurs on EUT and test instruments.
3) Electromagnetic Environment
Electromagnetic environment of laboratory should not affect the test results.
4) Conducting Surge Tests in the Laboratory
The signal generator and the coupling / decoupling network should be calibrated before the test. Performance checks are usually limited for the presence of surge pulses and their voltages and / or currents.
The test shall be conducted in accordance with the test program, which shall specify the test configuration and shall include the following elements:
— Test grade (voltage)；
— Surge number;
Unless specified in the relevant product standards, the number of surge pulses applied on the DC power source and the interconnection line shall be five times positive and five times negative, and five positive and five negative pulses shall be applied to the AC power supply port at 0 °/ 90 °/ 180 °/ 270 °phase respectively;
— Time interval between continuous pulses: 1min or shorter；
— Typical working condition of EUT
— Position of the surge applied
The power port (DC or AC) may be an input or output port.
Note 1: a. It is recommended that the surge be applied to the output ports that can easily carry the surge into the EUT (e.g. switching load with high power loss). For example, when secondary circuits (isolated from AC power ports) do not suffer directly from transient high voltage (e.g., reliably grounded, capacitance-filtered DC secondary circuits, the ripple of peak value is less than 10% of that produced by tributary element), the DC input/output of low voltage (equal or less than 60V) cannot carry out surge test.
b. In the case of several identical lines, only a certain number of lines should be selected for typical measurements.
c. If the repeat rate of surge in the test is shorter than 1/min and as a result the EUT goes wrong, and if the 1/min repetition rate is used to test the EUT and the EUT works normally, the 1/min repetition rate is usually used for the test.
Note 2: If the product is suitable, the product committee may choose different phase angles, or increase/decrease the number of surges per phase.
Note 3: a. For common surge protection devices, although their peak voltage and peak power can withstand large currents, their average power is low. Therefore, the interval between the two surges depends on the EUT built-in protection device.
b. When line-ground testing is carried out, if there are no other regulations, the test should be carried out in turn.
c. The test procedure shall take into account the nonlinear current-voltage characteristics of the equipment under test, so that the test voltage can only be incrementally increased from a low grade to the test level specified in the product standard or test plan / report and cannot exceed it. All lower grades (including selected test grades) shall meet the requirements.
d. For the second stage protection test, the output voltage of the signal generator should be increased to the lowest voltage breakdown value of the first stage protection. If no actual working signal source is provided to the EUT, it can be simulated.
e. For acceptance tests, equipment that has not previously been surge should be used, otherwise protective devices should be replaced prior to testing.
4. Evaluation of test results
The test results shall be classified according to the loss of function or deterioration of the performance of the tested equipment, and the relevant performance level shall be determined by the manufacturer or the demand party of the equipment, or by the agreement of the manufacturer and the buyer of the product. It is proposed to classify according to the following requirements:
a) The performance is normal within the limits specified by the manufacturer, the client or the purchaser.
b) Temporary loss or reduction of function or performance, but self-recovery after cessation of harassment without the need of intervention by the operator;
c) Function or performance is temporarily lost or reduced, but operator intervention is needed to recover.
d) Unrecoverable loss of function or reduction of performance due to equipment hardware or software damage or data loss.