Surge Protection Device Classifications

In a previous article, we introduced the one of the classification of surge protection device, that is, by type or class. Type 1/2/3 is the most common SPD classification either in UL standard or IEC standard. You can review this article via this link:

And in this article, we are going to talk more about other classifications which are not introduced at the above article.


Evidently, AC SPD is much more common than DC SPD as we all live in a society in which most electrical products are powered by AC current thanks to Thomas Edison. Maybe that’s why the IEC 61643-11 standard only applicable for AC surge protective device for quite a long time there is no applicable IEC standard for DC surge protective device. DC SPD become popular as the rise of the solar power industry and people notice that PV installation is a common victim of lightning as it is normally located in open area or on rooftop. So the need of surge protection devices for PV application is growing rapidly during the past 10 years. PV sector is the most common and popular application for DC SPD.

Surge protection professionals and organization realize that the exisiting IEC 61643-11 is not a perfect standard for PV SPD as it only applicable in low voltage power system under 1000V. Yet PV system’s voltage may up to 1500V. Therefore, a new standard called EN 50539-11 launched to address this problem. IEC also reacted to this situation and launched IEC 61643-31 for the application of PV SPD in 2018.

IEC 61643-11:2011

Low-voltage surge protective devices – Part 11: Surge protective devices connected to low-voltage power systems – Requirements and test methods

IEC 61643-11:2011 is applicable to devices for surge protection against indirect and direct effects of lightning or other transient overvoltages. These devices are packaged to be connected to 50/60 Hz a.c. power circuits, and equipment rated up to 1 000 V r.m.s. Performance characteristics, standard methods for testing and ratings are established. These devices contain at least one nonlinear component and are intended to limit surge voltages and divert surge currents.

IEC 61643-31:2018 

Low-voltage surge protective devices – Part 31: Requirements and test methods for SPDs for photovoltaic installations

IEC 61643-31:2018 is applicable to Surge Protective Devices (SPDs), intended for surge protection against indirect and direct effects of lightning or other transient overvoltages. These devices are designed to be connected to the DC side of photovoltaic installations rated up to 1 500 V DC. These devices contain at least one non-linear component and are intended to limit surge voltages and divert surge currents. Performance characteristics, safety requirements, standard methods for testing and ratings are established.  SPDs complying with this standard are exclusively dedicated to be installed on the DC side of photovoltaic generators and the DC side of inverters. SPDs for PV systems with energy storage (e.g. batteries, capacitor banks) are not covered. SPDs with separate input and output terminals that contain specific series impedance between these terminal(s) (so called two-port SPDs according to IEC 61643-11:2011) are not covered. SPDs compliant with this standard are designed to be permanently connected where connection and disconnection of fixed SPDs can only be done using a tool. This standard does not apply to portable SPDs.

This is change in IEC standard. In UL standard, the latest UL 1449 4th edition introduced the contents for PV SPD which was not exist in the 3rd edition. So finally, all standard organizations launched their standards for DC/PV surge protection device.

Let’s take a look at Prosurge’s PV SPDs.

Class 1+2 Type 1+2 SPD for PV Solar DC - Prosurge-400
PV DC SPD Class 2 Type 2 UL-Prosurge-400
PV DC SPD Class 2 Type 2 TUV-Prosurge-400

Surge Protection Classification by Applications

Traditionally, surge protection devices can be classified by applications like:

  • SPD for power supply
  • SPD for Signal
  • SPD for Video
  • SPD for Network
  • ect

Here we can see some pictures of SPD in such classification.

SPD for Ethernet single port-Prosurge-300-New
SPD for video webcam CCTV single port-Prosurge-300-New

SPD for Power Supply

SPD for Signal

SPD for Ethernet

SPD for Video

SPD Classification by Mounting/Appearance

Typically, besides type 3 SPDs which normally refer to power strips and receptacles and adopt plug-in moutning. There are two common mountings: DIN-rail mounting and panel mounting. Here are the pictures of DIN-rail mounting SPD and Panel mounting SPD.

We can clearly notice that they have a distinc apprerances.


Panel Mounted SPD


DIN-rail Mounted SPD

Let’s look at some of their installtion pictures so that we can understand better how these SPDs are installed.

Surge Protection Project in El Salvador (1)-1

Panel Mounted SPD

Surge-Protection-Projects-Nigeria-Prosurge-500-2 (2)

DIN-rail Mounted SPD


In this article, we exentend our discussion on the classfication of surge protective device. We talk about the classificication by AC/DC, by applications and by installation. Of course, there are other standards to classify and it is quite subjective. We hope that this article can help you understand better surge protection device.