Hardware knowledge: lightning surge test of switching power adapter

The national standard for lightning surge immunity test of switching power adapter is GB/T17626.5. There are two versions in China in 1999 and 2008, respectively, and the international standards IEC61000-4-5:1995 and IEC61000-4-5. :2001 is equivalent.
Since most domestic product standards have not been revised, the current two standards, GB/T17626.5-1999 and GB/T17626.5-2008, coexist in China.

Lightning strikes are extremely common natural phenomena. According to statistics, there are more than 40,000 thunderstorm centers around the world, with 8 million lightning strikes per day, which means that there are about 100 lightning strikes per second on Earth. Therefore, the lightning surge test of the switching power adapter can establish a common basis for evaluating the switching power supply when subjected to high energy pulse interference.

The standard mainly simulates indirect lightning strikes (switching power supplies are usually unable to withstand direct lightning strikes), such as: 1 lightning strikes the outdoor grid line, a large amount of current flows into the external line or grounding resistance, thus generating interference voltage; 2 indirect lightning strikes (such as clouds or clouds) The lightning strike inside induces the pulse voltage and current on the external power grid line; 3 lightning strikes the adjacent object of the line, and the strong electromagnetic field established around it induces the voltage on the external line; 4 lightning strikes the nearby ground, and the ground current passes. Interference introduced when the public grounding system is used. See the news of Guangzhou Tianhao Technology Co., Ltd. for details.

The surge immunity test standard of the power adapter simulates the lightning strike in the natural world. It also mentions the interference introduced by the switch operation, such as: 1 interference when the main power system is switched; 2 the same power grid, The interference formed when some small switches near the switching power adapter are beating; 3 switching the thyristor equipment with the resonant line; 4 various systemic faults, such as short circuit and arcing fault between the equipment grounding network or the grounding system.

1. Lightning surge immunity test method:

(1) Layout and configuration according to the actual use and installation conditions of the test article, including some standards that will change the additional resistance that reflects the internal resistance of the waveform generator signal source.

(2) Determine the grade and test location of the test voltage according to the product requirements.

(3) At each selected test site, the positive and negative polarity interferences must be increased by at least 5 times, and the maximum repetition rate per surge is 1 time/min. Since the protection devices used in most systems have a recovery period between the two surges, there is a problem with the maximum repetition rate of the equipment during the lightning surge test.

(4) Whether the injection of the surge wave is synchronized with the input voltage of the switching power supply adapter. If there is no special regulation, it is usually required to superimpose the lightning surge signal on the zero-crossing point and the positive and negative peak positions of the switching power supply adapter voltage waveform.

(5) Considering the nonlinearity of the voltage-current conversion characteristics of the device under test, the test voltage should be gradually increased to the specified value of the product standard to avoid possible artifacts in the test (at high test voltage, because there may be somewhere in the device under test) A weak device breaks down and bypasses the test voltage, causing the test to pass. However, at low test voltages, since the weak device is not broken down, the test voltage is applied to the test equipment at full voltage, which makes the test impossible. . See the news of Guangzhou Tianhao Technology Co., Ltd. for details.

(6) Lightning surge signals should be added between line-line or line-ground. If a line-ground test is to be performed and there is no special regulation, the test voltage is applied between each line and ground in turn. However, it should be noted that in the line-ground test, there are sometimes cases where the standard requirement is to superimpose the interference on two or more pairs of grounds at the same time, and the duration of the pulse is allowed to decrease.

(7) Since the test may be destructive, never let the test voltage exceed the specified value.
Http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn

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