T1: Type 1 test, which is a surge protection device (SPD) tested with the nominal discharge current In, the 1.2/50μs impulse voltage, and the maximum impulse current Iimp. T2: Type 2 test, which is a surge protection device (SPD) tested with the nominal discharge current In, the 1.2/50μs impulse voltage, and the maximum discharge current Imax.