Surge protection device is an indispensable device in lightning protection of electronic equipment. In the past, it was often called "lighting protector" or "over-voltage protector", abbreviated as SPD. The function of surge protection device is to limit the instantaneous over-voltage of the power line and signal transmission line to the voltage range that the equipment or system can withstand, or to drain the powerful lightning into the ground to protect the equipment or system from being damaged by impact.
The type and structure of surge protection device by CHENZHU, a reliable company specializing in safety and automation system vary for different purposes, but it should contain at least one nonlinear voltage limiting element.
Surge protection device is classified according to its working principle:
1. The working principle of switch type AC or DC surge protection device is that it appears as high impedance when there is no instantaneous over-voltage, but once it responds to lightning instantaneous over-voltage, it suddenly changes to low impedance and allows lightning current to pass through.
2. The working principle of voltage-limiting surge protection device is that it has high resistance when there is no instantaneous over-voltage, but its impedance decreases with the increase of surge current and voltage, and its current-voltage characteristics are strongly nonlinear.
3. Shunt type or choke type surge protection device is the third type SPD surge protection device. Shunt type has parallel connection with the protected equipment, showing low impedance for lightning pulses and high impedance for normal operating frequency. The choke type is in series with the protected equipment, showing high impedance for lightning pulses and low impedance for normal operating frequency.
The categories of surge protection device by use are:
1. Power protection device: AC power protection device, DC power protection device, switch type power protection device and so on.
2. Signal surge protection device: low frequency signal protection device, high frequency signal protection device, antenna surge protector and so on.