Surge generator anti-interference measurement is based on the international standard IEC 61000-4-5.
1 Test objective
The entire lightning stroke in the nature (namely the indirect thunder such as the lighting stroke between the clouds, or the lighting stroke happened to the adjacent objects) can induce the surge voltage and current in outdoor aerial. Besides, huge surge voltage and current will also be induced in the supply circuit of the instant switch in the power station or switching station. The common characteristics of the two kinds of surge include high energy (compared with the energy, the static electricity is P joule level, pulse group is the millijoule level, lightning surge is hundreds of the joule level, which is one million times of the former two interfering energy), slow waveform (microsecond level, but the static electricity and pulse group are nanosecond level, even the sub nanosecond level), and low recurrence frequency.
IEC 61000-4-5 is a standard that provides an objective evaluation on the resistance to surge interference ability for the electrical and electronic equipment through the experiment of simulating lighting surge.
2 Surge generators
This standard has mentioned two kinds of surge generators, which respectively simulate the situation of the power line and the communication line. The waveforms of the two kinds of surge are different because of the different line impedance.
(1)Comprehensive wave generator used for the power lines test
“Comprehensive wave” refers to the waveform parameters formed by the voltage wave and the current wave regulated by the standard in a generator (when the output terminal of the generator is open circuit, it will form the voltage surge wave; when the output terminal of the generator is short circuit, and it will form the current surge wave). The requirement of the generator line and the waveform is shown as the following figures:
U: High-voltage power supply
Rs: Pulse duration forming resistor
Rc: Charging resistor
Rm: Impedance matching resistor
Cc: Reservoir capacitance
L: Rising time forming resistor
Front wave time: T1=1.67XT=1.2μs±30%
Half peak value time: T2=50μs±20%
1.2/50μs Open-circuit voltage waveform (based on IEC 60-1 waveform regulation)
Front wave time: T1=1.25XT=8μs±30%
Half peak value time: T2=20μs±20%
8/20μs Open-circuit voltage waveform (based on IEC 60-1 waveform regulation)