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A common question after a lightning storm, switching event, or unexpected voltage surge is: does an SPD need to be replaced after a surge? The short answer is no—not automatically. A surge protective device is designed to limit transient overvoltage…

If you look at a typical surge protective device (SPD) installation, you may notice something different from a fuse or circuit breaker. A fuse or circuit breaker is normally installed in series with the circuit, so the load current passes…

Knowing how to test an SPD is not as simple as placing a multimeter across its terminals and checking for continuity. A surge protective device is designed to respond to short-duration overvoltage events that are far beyond the normal output…

Wondering how to know if an SPD is bad? The status indicator is usually the first place to check, but it cannot tell you everything about the condition of a surge protective device. A surge protective device (SPD) can continue…

You open the solar distribution box, look at the surge protective device, and see a green indicator. The SPD green indicator looks normal, but does that mean the system is actually protected? Everything looks normal. So does that mean the…

SPD distance from inverter is an important part of solar PV surge protection design, especially when the SPD is installed in a combiner box or near the PV array. You have installed a DC surge protective device in the PV…

A solar inverter built-in SPD can provide important surge protection, but seeing “DC Type II SPD” on the datasheet does not automatically mean the entire PV system is protected. Sometimes the specification even says: Built-in Type II DC & AC…

A DC surge protective device may look simple from the outside, but the markings printed on its label contain important information about where the SPD can be used and how it performs. Consider this example from a 1000V DC solar…

A Practical Guide to Choosing 600V, 1000V and 1500V DC Surge Protective Devices Introduction DC SPD selection is one of the most important steps in designing a reliable solar photovoltaic (PV) protection system. Selecting the correct voltage rating of a…

When comparing Type 1 vs Type 2 SPD for solar applications, Type 1, Type 2 and Type 1+2 SPDs should not be treated as three quality levels of the same product. They are intended for different surge conditions. In many…