SPD Supply: A Strong Backing for Power Equipment

SPD supply is a protective device installed in power lines to prevent damage to electrical equipment caused by transient overvoltage or overcurrent due to lightning strikes. The primary function of SPD supply is to eliminate sudden overvoltage and overcurrent in the power system, protecting equipment from lightning and other factors.

Classification of SPD Supply

According to the working principles and structural characteristics of surge protectors, SPD supply can be classified into the following categories:

Voltage-limiting Surge Protectors

These use nonlinear components (such as varistors, avalanche diodes, zinc oxide, etc.) that exhibit high impedance during normal operation and low impedance when encountering overvoltage, thereby limiting the overvoltage to a certain range to protect downstream equipment. The advantages of voltage-limiting surge protectors are fast response speed and low energy consumption; the disadvantage is limited capacity, and they cannot withstand high currents.

Switching Surge Protectors

These use switching components (such as gas discharge tubes, spark gaps, thyristors, etc.) that exhibit high impedance during normal operation and suddenly conduct when encountering overvoltage, thus directing the overcurrent into the grounding line to protect downstream equipment. The advantages of switching surge protectors are high capacity and the ability to withstand high currents; the disadvantage is slower response speed, requiring them to be used in conjunction with voltage-limiting surge protectors.

Current-limiting or Shunting Surge Protectors

These use inductors or capacitors that exhibit low impedance during normal operation and high impedance when encountering overvoltage or overcurrent, thereby suppressing or shunting overvoltage or overcurrent to protect downstream equipment. The advantages of current-limiting or shunting surge protectors are that they do not affect normal operation; the disadvantage is small capacity, requiring them to be used in conjunction with other types of surge protectors.

Working Principle of SPD Supply

SPD supply is generally connected in parallel between the power line and the load. When overvoltage occurs on the power line, the power surge protector will divert or limit it, thereby protecting the load equipment.

Working Stages of SPD Supply

Normal Operation Stage

The power surge protector is in a high impedance state and does not affect the normal operation of the power line and load.

Trigger Stage

When overvoltage occurs on the power line, the impedance of the power surge protector decreases, starting to conduct, forming a low impedance path to divert or limit the overvoltage.

Protection Stage

The power surge protector continues to conduct, directing the overvoltage into the grounding line or limiting it within a certain range, protecting the load equipment from damage.

Recovery Stage

After the overvoltage on the power line disappears, the impedance of the power surge protector recovers, returning to a high impedance state, ending the protective action.

Industry Applications of SPD Supply

SPD supply is used in various fields, such as telecommunications, power, transportation, industry, agriculture, and civilian sectors. The role of SPD supply is to ensure normal operation and safe production in these fields.

Telecommunication Industry

Equipment and systems in the telecommunications industry require high stability and reliability of the power supply. Therefore, the telecommunications industry needs to install SPD supply on power lines to prevent overvoltage or overcurrent caused by lightning or other factors, ensuring the normal operation of communication equipment and systems. For example, in the power lines of base stations, switches, routers, servers, etc., primary or secondary SPD supply can be installed to withstand the effects of direct or induced lightning strikes.

Power Industry

In the power industry, a power supply failure can lead to serious consequences such as power supply interruption, grid instability, or equipment burnout. Therefore, the power industry needs to install SPD supply on power lines to prevent overvoltage or overcurrent caused by lightning or other factors, ensuring the normal operation of power equipment and systems.

Transportation Industry

The transportation industry needs to install SPD supply on power lines to prevent overvoltage or overcurrent caused by lightning or other factors, ensuring the normal operation of transportation equipment and systems. For example, in the power lines of traffic lights, surveillance cameras, navigational instruments, and radars in railway, highway, aviation, and maritime transportation fields, primary or secondary SPD supply can be installed to withstand the effects of direct or induced lightning strikes; in the power lines of vehicles, ships, airplanes, etc., tertiary or quaternary SPD supply can be installed to eliminate residual overvoltage or overcurrent on the power lines, ensuring the safety of transport vehicles.