Composition and Function Analysis of Power Surge Protective Devices: Building Lightning Protection Barriers for Electronic Information Systems

As one of the most destructive natural disasters, lightning causes

enormous material losses and casualties worldwide every year. With the

large-scale application of electronic devices and microelectronic integrated

systems, incidents of equipment and system damage caused by Lightning

Overvoltage (LPS) and Lightning Electromagnetic Pulse (LEMP) are

increasing. Therefore, strengthening the lightning disaster protection

capabilities of buildings and electronic information systems is urgent.

Installing Power Surge Protective Devices (SPDs) is a critical link in

ensuring safety in production. Establishing a comprehensive and

systematic lightning surge overvoltage protection system can

significantly reduce the risk of lightning strikes to buildings and

equipment.

So, what are the core components of a power surge protective device?

The core function of a Surge Protective Device (SPD) is voltage clamping, which means limiting transient overvoltages within a safe range

tolerable by the protected equipment. Therefore, voltage-clamping components are its core. It primarily relies on the coordinated operation of key components including the spark gap, gas discharge tube

(GDT), varistor (Metal Oxide Varistor - MOV), and suppression diode.

Spark Gap: Consists of a pair of metal electrodes exposed to the

atmosphere, connected to the power line and ground line respectively.

Under normal conditions, it presents a high-impedance open state. When the line experiences a transient overvoltage, the gap is broken down by high voltage, forming a conductive path to

rapidly divert part of the overvoltage energy to the ground, preventing

damage to protected equipment due to a sudden voltage surge.

Gas Discharge Tube (GDT): Structurally contains a pair of metal

electrodes encapsulated in an inert gas environment (such as Argon, Ar), with a precise discharge gap reserved between them. When the voltage

across its terminals exceeds its ignition voltage threshold, the gap

breaks down and conducts. To improve response reliability and

consistency, some products incorporate triggering agents.

Varistor (MOV): The primary material is Zinc Oxide (ZnO), exhibiting

significant voltage sensitivity. When the voltage across its terminals

exceeds its rated operating voltage (varistor voltage), its resistance

value drops sharply, enabling rapid conduction and shunting. Its non-linear voltage-current (V-I) characteristic, similar to a combination of multiple PN junctions,

allows it to respond extremely quickly to transient overvoltages on the

nanosecond scale. In SPD design, the selection, structural layout, and

thermal management of varistors are crucial to overall performance.

Suppression Diode (e.g., TVS Diode): Typically serves as the core

component of the SPD's fine protection stage, operating in the

avalanche breakdown or Zener breakdown region. Its response speed is

extremely fast (picosecond level) and can precisely clamp overvoltages

to a very low level, providing sensitive electronic equipment with a

final, robust voltage defense line.

Power Surge Protective Devices are indispensable equipment for ensuring

the safe and stable operation of electrical systems. They not only

effectively suppress circuit switching overvoltages but also efficiently divert massive lightning overvoltage energy. Consequently, SPDs demand

exceptionally high levels of stability and reliability.

For example, the Kaitai Surge Protective Device series has undergone

rigorous testing and certification by the authoritative national body – the Lightning Protection Performance Quality Supervision and Testing

Center for Communication Products, Ministry of Information Industry.

Test results demonstrate its superior performance, full compliance with

relevant technical standards, and significant effectiveness in surge

isolation and surge diversion. This adds a reliable layer of safety

assurance for protected equipment or systems, ensuring safer and more

secure usage.