How Do We Choose A Surge Protector For The Rooftop Distribution Box?
Article 3 of Section 5.4.3 of GB 50343-2012 stipulates: For AC power supply lines entering buildings, at the junction of LPZ0A or LPZ0B and LPZ1 areas such as the main distribution box of the line, a surge protector of Class I test or a surge protector of Class II test should be installed as the first level of protection;
National standard interpretation: You can choose either a first-level surge or a second-level surge protective device.
Basis for selection of surge protector:
National standard stipulates that the flow rate of surge protection device can be different for buildings with different protection levels. Therefore, how to select a surge protector specifically depends on the lightning protection level of the building.
National standard GB 50343-2012 Section 4.3.1: The electronic information system of a building can be classified according to Table 1-2 based on its importance, economy and value.
If your project is a first-level protection building, you can choose a first-level surge protector of more than 20KA. If you want to choose a second-level surge, you need to choose a surge protector with In≥80KA. From an economic point of view, the cost of a second-level surge with In exceeding 80KA is almost the same as that of a first-level surge. It is recommended that the rooftop equipment directly use a first-level surge protector, which has a larger flow rate and a longer lightning protection.
Other building classifications are analogous to the requirements in the table. At present, the most common first-level surge protector is 25KA, which is almost the same cost as 15KA. The use of a surge protector with a larger flow rate will have a longer service life.
