На всякий случай - позволю себе обрать внимание на параметр "I2t value for fusing", снимаемый при весьма характерном tp = 10 ms. В
описаниях предохранителей оно же фигурирует под названием "melting
integral". Вот, что считает по этому поводу ON Semi в "Thyristor
Theory and Design Considerations Handbook" (HBD855) применительно к
"ломовой" защите: It would seem that the matching of the fuse to the SCR would be straightforward — simply ensure that the fuse rms current rating never exceed the SCR rms current rating (Figure 5.15), but still be sufficient to handle steady−state and normal overload currents. The more exact relationship would involve the energy dissipated in the system ∫ I2Rdt, which on a comparative basis, can be reduced to I2t. Thus, the “let−through” I2t of the fuse should not exceed I2t capability of the SCR under all operating conditions. These conditions are many, consist- ing of “available fault current,” power factor of the load, supply voltage, supply frequency, ambient temperature, and various fuse factors affecting the I2t.