Classification of first, second and third level surge protection devices

Because some customers have consulted us about the classification of first, second and third level surge protection devices, now we will make a brief introduction. According to IEC standards, for the AC power supply line entering the building, the junction of LPZ0A or LPZ0B and LPZ1 area such as the main distribution box of the line should be equipped with the surge protector of Class I test or the surge protector of Class II test as the first level protection; At the junction of subsequent protection areas such as distribution line distribution box and distribution box of electronic equipment room, the surge protector of Class II or III test can be set as the post protection; Especially important electronic information equipment power ports can be installed Class II or Class III test surge protectors for fine protection.

First-level（Class I） surge protection device: Through 10/350μs waveform test, the maximum impact current limp value is 12.5KA,15KA,20KA,25KA. The main function is to discharge flow.Refer to Thor TRS-A series of SPDs.

Second-level （Class II）surge protection device: by 8/20 mu s wave test, the parameters of the maximum discharge current lmax commonly used 20 ka, ka 40, 60 ka, ka, 80 100 ka, main effect is limited.Refer to Thor TRS4 series of SPDs.

Third-level （Class III）surge protection device: Pass the test of the combined waveform (1.2/50μs), the characteristics of the product must also withstand the test of the waveform (8/20μs). It is usually a compound surge protector, whose function is to clamp the pressure, which can provide finer protection for the end equipment.Refer to Thor TRS series of SPDs.

In actual projects, we often encounter various technical specifications, especially the selection of the parameters Uc of the first, second and third level surge protectors, which have different requirements from 275V to 440V. Therefore, we should strictly consider this problem from the perspective of professional technology. Usually on the premise of meeting the voltage value of the equipment to be protected, we are used to choose the Uc value of 320V-385V, which is much higher than the phase voltage in the line, so as to prolong the service life of the surge protector.

According to IEC standards: when setting the level of surge protector, factors such as protection distance, length of connecting wire of surge protector and shock voltage rating UW of the equipment to be protected should be considered comprehensively. All levels of surge protectors shall be able to withstand the expected discharge current at the installation point, and their effective protection level UP/F shall be less than the UW of the corresponding protected equipment.

Through the above introduction of the classification of first, second and third level surge protection devices, you will not be confused when you encounter such problems. For details about the parameters of the first, second and third level surge protection devices, you can contact our THOR lightning Protection for consultation. We will conduct specific analysis according to the different use environment in different areas of different projects to ensure that there is no mistake.