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What is SPD energy coordination?
Dec 17 , 2025
The so-called energy coordination means that when multiple levels of SPDs or protective elements have different discharge capacities and are used together, the lightning current must be reasonably distributed to ensure that the SPDs or elements with smaller discharge capacities are not damaged. As shown in the figure below, SPD1 has a high discharge capacity and a high residual voltage, while SPD2...
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What is the "clamping voltage" of SPD? What is the core role in SPD, and how it related to the "voltage protection level"?
Feb 05 , 2026
The clamping voltage is a dynamic performance parameter, specifically referring to the peak voltage across the terminals of a surge protective device (SPD) when its core nonlinear element (such as a metal oxide varistor (MOV) or avalanche diode (TVS)) conducts and discharges a surge current of a specific waveform and amplitude. It is essentially the highest voltage established by the SPD during th...
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Now SPD monitoring has gone far beyond simple "on/off" indications. What intelligent directions is it developing towards?
Mar 12 , 2026
Traditional SPD monitoring only provides a dry contact signal based on a mechanical disconnector, which is a typical "post-failure alarm"—it informs the user that the SPD has completely failed and needs to be replaced. Modern intelligent monitoring modules, however, utilize built-in microprocessors and sensors to transform the SPD from a passive protection component into an intelligent node capabl...
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What are the main types of coaxial signal SPDs? What are the differences in their working principles, technical characteristics, and application scenarios?
Apr 09 , 2026
Coaxial SPDs can be mainly classified into gas discharge tube, semiconductor voltage limiting, DC isolation, and quarter-wavelength technologies based on their technical principles. Among these, gas discharge tube and semiconductor voltage limiting types form the core of basic protection, while DC isolation and quarter-wavelength technologies are key designs for achieving specific functions. 1. Ga...
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Can the explosion-proof grade Ex db IIC T6Gb of the on-site instrument SPD replace Exd IIC T4 Gb?
Apr 13 , 2026
Can the explosion-proof grade Ex db IIC T6Gb of the on-site instrument SPD replace Exd IIC T4 Gb? Conclusion: The Ex db IIC T6 Gb rating fully meets and exceeds the requirements of Exd IIC T4 Gb and can be safely used as a replacement. This conclusion is based on the core principle of "higher ratings are compatible with lower ratings" in the selection of explosion-proof equipment, and the specific...
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For SPDs used in high-altitude areas, the electrical clearance needs to be increased. How does the GB/T 18802.11 standard reflect this requirement in testing and certification?
Apr 28 , 2026
The GB/T 18802.11 standard explicitly acknowledges the influence of altitude on electrical clearance insulation strength and incorporates this through an "altitude correction factor" in the testing conditions. The standard typically uses 2000 meters as the baseline altitude. For surge protective devices (SPDs) claimed to operate normally at higher altitudes (such as 5000 meters), the testing requi...
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How is the Up value determined in an SPD with multiple protection modes (such as L-N, L-PE, N-PE)? What is the important guiding significance of SPD selection
Jun 26 , 2026
According to the standard, the declared Up value of a multi-mode SPD is the maximum residual voltage value measured across all its protection modes. For example, for a three-phase SPD, if the residual voltage is 1.5 kV in L-PE mode, 1.8 kV in L-N mode, and 2.0 kV in N-PE mode, then the Up value of this SPD should be specified as 2.0 kV. This means that the protection level provided by this SPD to ...
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The roles for "impulse breakdown voltage" and the "DC breakdown voltage" in gas discharge tubes in SPDs?
Jul 30 , 2026
This is determined by the physical characteristics of the GDT and its different roles in the circuit. Impulse breakdown voltage (e.g., for a rise rate of 1 kV/μs): This parameter characterizes the response speed of the GDT to fast transient overvoltages. Standards require high stability (low dispersion) because GDTs are often used as primary protection and need to operate quickly and predictably t...
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