Surge Protector Protection Level Up Selection

The value of Up is similar to the residual voltage value of the surge protector (but Up is not the residual voltage). When the surge protector is activated, a part of the residual voltage will be loaded on the device end.

Therefore, the voltage protection level Up of the surge protector is generally required to be less than the equipment's impulse withstand voltage value Uw. Considering the residual voltage increase caused by wiring, it is recommended that the surge protector's Up≤Uw*0.8.

According to IEC60364-4 and GB50057-2010, the equipment insulation impulse withstand voltage ratings in the 220/380V power distribution system in the building are divided into 4 categories:

The requirements of the lightning protection standard for the surge protector Up are generally:

① The first-level surge protector Up≤2.5kV of the main incoming line cabinet

② The second-level lightning protector Up of the rear-stage distribution cabinet is not mandatory, and 1.7kV or 2.1kV is generally selected

③ The final lightning protection Up≤1.2kV in the environment such as the computer room

Under the same conditions, the lower the Up value, the better