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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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