Select According To The Residual Voltage Value Of The Surge Protector

Simply considering the lower the residual voltage for a surge protective device, the better is incomplete and easily misleading. First, the nominal residual voltage values ​​for different products must specify the test current magnitude and waveform to provide a common basis for comparison. Residual voltage is generally recorded at a 20kA (8/20μs) test current for comparison.

Second, for a surge protector, a lower residual voltage typically means a lower maximum continuous operating voltage (Uc).

Third, overemphasizing low residual voltage comes at the cost of lowering the maximum continuous operating voltage (Uc). Consequently, in areas with unstable mains power, a surge protection device can be easily damaged by prolonged overvoltage. For SPDs, maximum continuous operating voltage (Uc) and residual voltage are like two sides of a scale; neither should be emphasized. Based on experience, a residual voltage below 2kV (20kA8/20μs) provides adequate protection for user equipment.