Primary Protection Against Overvoltage Events
Pulse-shaped load currents are a common circuit occurrence and a typical factor for consideration when designing in primary fuses. Pulses can arise individually (Surge), or recurrently (e.g. timed circuits). With individual pulses, the I²t value of the fuse wire becomes quite important. This is because the higher the i²t value the greater the pulse tolerance; with pulse-shaped continuous currents, the calculation of the rms value is crucial, and generally the displacement of the rated current should be taken into account as a result of a possible increase in aging (diffusion).