What is SPD? (Surge Protector)

I received a  e-mail about a site where a PC suddenly freezes. When I mentioned that a surge attack might be the cause, they were unfamiliar with the term "surge."

A surge refers to a natural phenomenon where sudden overvoltage, such as lightning strikes or electrical spikes, enters the power system.

If a surge directly affects a PC, PLC, or HMI, it can cause serious damage. To prevent this, Surge Protector Devices (SPD) are available on the market.

How to Install an SPD

  • The SPD must be properly connected to the ground (earth).
  • This allows the surge energy to safely discharge into the ground.
  • You can think of it as similar to a lightning rod installed on buildings.
  • Without proper grounding, the SPD is completely useless.

So how do we wire it on site? Take a look at the picture below.

Jan 29th 2025

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