1. working principle:
(1) the SPD switch: it works for high impedance without transient over voltage, but a lightning transient overvoltage to a lower value, allowing lightning reaction of resistant mutations are passed. Equipment when such equipment is used: gap, gas discharge tubes, SCR and so on. (2) automatic limiting type SPD: how it works is when there is no transient overvoltage of high resistance, but with the current and voltage surge impedance reduces, nonlinear current-voltage characteristics of strong increases. For a device this device: zinc oxide Varistors, suppressor diode, avalanche diode. Now limited most of the SPD, long products too. (3) the type of shunt shunt or choke type lightning protection: protected equipment at the same time, lightning pulse for low impedance, and the operating frequency is high impedance.
Choke: protection devices, lightning impulse high-impedance and low impedance frequency range. As a component of such a device: choke coil, high pass filter, low pass filter, wavelength 1/4 breaker.
2. the purpose of the lightning:
(1) power supply lightning protection device: power supply, DC power supply, switching power supply lightning protection. (2) signal SPD: low frequency signal lightning, lightning protection equipment for high frequency signal, the antenna-feeder SPD. (3) combined Lightning: also known as the three-in-one SPD, referring to camera video surveillance system-side lightning protection and lightning protection lightning protection devices as a whole.
3. lightning protection level:
A: the General than 30KA. B: between nominal 15--20KA. C: General on behalf of the General 5-10kA can be.