Analysis of additional tests for SPD's failure mode in IEC61643.11

The introduction of additional test for SPD's failure mode simulation in SPD type of pilot projects transient overvoltage test in IEC61643.11. The standard stipulates that the SPD shall be with internal and external breakers can't be disconnected when we perform the impact of the lightning current experiment. And when we perform transient overvoltage test, SPD requires internal and external actions or products can be tolerated. So for the preliminary test of the class I and class II product, especially for external or internal breakers' unreasonable selection, the small current follow through the SPD product without product's breakdown and combustion with larger current. We conducted a preliminary analysis after the test. So how to select a internal breakers and design external breakers with function of over-current protection becomes the key problems.