CLASSIFICATION OF SPDs
Surge protective devices are tested in accordance with the classification and parameters provided by the manufacturer.
Depending on the intended application, according to HD 60364-5-534 or the EN 62305 series, there are three different test classes corresponding to three types of SPDs:
SPD type 1: tested with the impulse discharge current Iimp (typically 10/350 µs) and with 8/20µs current impulses.
SPD type 2: tested with the nominal discharge current In (8/20 µs) and optional with the maximum discharge current Imax (8/20µs).
Imax should not be considered for choosing an SPD.
When containing any voltage switching components SPDs type 1 and type 2 are additionally tested with 1,2/50µs voltage impulses.
SPD type 3: tested with a combination wave generator providing an open circuit voltage Uoc (1,2/50 µs) and a defined short circuit current Icw (8/20µs) with a fictive nominal output impedance of 2 Ω.
Maximum preferred discharge current values for type 1, type 2 and type 3 SPDs
in accordance with EN 61643-11