Research On Surge Protection Device Capability And Test Methods

In recent years, people enhance lightning protection consciousness and lightning protection technical development. Especially methods about lightning rod, down lead, earth body and so on; these methods use to cause the destruction that the directly lightning destroy to reduce. With directly lightning produce lightning electromagnetic pulse (LEMP) or thunder induction which the destroy effect emergence. From people pay great attention about internal lightning protection include of shield, equipotent connection, grounding system, sometimes these measures even also insufficient. Some electronic equipment capability of endures the over voltage quite bad. Some electric or electronic equipment capability of endures the over voltage quite bad. When install the good performance surge protection device (SPD) could be able to improve protection remarkable.This article has analyzed several essential characters of lightning currents. To simulation analysis about thunder current four mathematical expressions by matlab software. Compared with suitable mathematical model of simulate lightning voltage and current wave and amplitude frequency characteristic as well as the energy distribution. Draw the following: the double exponent function uses for to simulate testing wave 10/350μs,1.2/50μs, power series function fit for to simulate 8/20μs. The common ground is frequency spectrum which the simulation lightning currents contain from low frequency to high frequency, and concentrates in low frequency. Through the analysis of spectrum obtain about energy concentrates in 10 kHz, when above 1MHz, the energy distribution tends 0. Wave gradient have energy distribution related. The spectrum and the energy distribution conform to the domestic and foreign researcher to the actual thunder observation analysis result.Has analysis to the commonly SPD test method. Spread out research to the SPD performance in this foundation. Carries on the experiment to varistor several kind of combinations, obtains the feasible combination way. And does the experiment about switch type and limit voltage type surge protection device. The appropriate inductance values between two classes could effective distributaries over-voltage, over-current on line. Inductance could also reduce current wave rise gradient that affects latter MOV and decrease high frequency to equipment. The experiment about respond characteristic of under the lightning current and voltage to common use over-voltage protection component. Gave design method about surge protection device of electronic equipment.This article according to the wave refraction or reflection and Peterson principle, replaces the distributed parameter line by the lumped parameter equivalent circuit. It had analyzed over-voltage protection combination with other components. Including capacitance, inductance, T low pass filter. Do the simulations researches with electromagnetism transition process computation software ATP, indicates the output voltage gradient and the peak-to-peak value have related to filter time-constant. The T circuit characteristic impedance and the filter time can affect the limiting pressure effect. The data obtains from the emulation sends in matlab for spectral analyses indicated can obviously suppression high frequency with the above combination. Finally pointed out for better filtration high frequency in lightning over-voltage, except may use common low pass filter circuit like T, LC and so on, but also may make the improvement to the filter circuit, or uses the multistage protection circuit to obtain a better high frequency weaken.