Surge protectors are of different types and configurations for different purposes, but they should contain at least one nonlinear voltage limiting element. The basic components used in surge protector include discharge gap, gas-filled discharge tube, varistor, suppression diode and choke coil.
Classification of SPD:
1. Surge protector according to working principle:
(1) switching type: its working principle is that when there is no instantaneous overvoltage, it presents a high impedance, but once it responds to the instantaneous overvoltage of lightning, its impedance changes to a low value, allowing lightning to flow through. When used as such devices, the devices include: discharge gap, gas discharge tube, thyratron transistor, etc.
(2) voltage limiting type: its working principle is high resistance when there is no instantaneous overvoltage, but its impedance decreases with the increase of inrush current and voltage, and its current and voltage characteristics are strongly nonlinear. The devices used for this kind of device include zinc oxide, varistor, suppression diode, avalanche diode, etc.
(3) shunt or choke
Shunt: in parallel with the protected device, low impedance to lightning pulse and high impedance to normal working frequency.
Choke type: in series with the protected equipment, high impedance to lightning pulse and low impedance to normal working frequency.
The devices used for this kind of device are: choke coil, high pass filter, low pass filter, 1/4 wavelength short circuit, etc.
2. Surge protectors are of different types and configurations for different purposes, but they should contain at least one nonlinear voltage limiting element. The basic components used in surge protector include discharge gap, gas-filled discharge tube, varistor, suppression diode and choke coil. By purpose:
(1) power protector: ac power protector, dc power protector, switch power protector, etc.
(2) signal protector: low-frequency signal protector, high-frequency signal protector, antenna feeder protector, etc.