Lightning surge generator experiment standard: Even if the same equipment is used for the lightning surge generator immunity test, different test methods and test purposes will use different combination/disaster network parameters. For example, it is used for the test of power line anti-differential mode T. interference. Because the line impedance is very low, the standard stipulates that the coupling capacitance is 185F, and the internal resistance of the generator is 20. This represents the signal source differential mode of the low-voltage power supply network. impedance. In the anti-common-mode interference test, the standard stipulates that a 1x1) resistor should be connected in series with the output loop of the generator as the common-mode impedance of the signal source of the low-voltage power supply network. For some other tests, for example, the lightning surge immunity test on the signal line, since the signal line impedance is much higher than the power line, the generator needs to add a series resistance of 400 to represent the resistance on other lines ( Except for the power line) impedance to ground.

　　 The surge voltage generated by lightning comes from several aspects:

　　①A direct lightning strike acts on the external circuit, and the injected large current flows through the ground resistance or the external circuit impedance to generate a voltage

　　②Indirect lightning strikes that induce voltage and current on the inner and outer conductors of the building.

　　③The nearby lightning current discharged directly to the ground is coupled to the common ground loop of the equipment grounding system. When the protection device is activated, the voltage and current may change rapidly and may be coupled to the internal circuit.

The 　　 standard describes two different waveform generators: one is the waveform produced by the induction of lightning on the power line. Both of these lines are empty overhead lines, but the impedances of the lines are different: the surge waveform induced on the power line is narrower (50uS), and the leading edge is steeper (1.2uS). The surge waveform induced on the communication line is wider, but the leading edge is slower. Later, we mainly analyze the circuit with the waveform produced by the induction of lightning on the power line. At the same time, we also briefly introduce the lightning protection technology of the communication line.