BACK-UP PROTECTION BY H.R.C. FUSES

For applications in which fault currents larger than the contactor's breaking capacity, or with peak values higher than those which cause the repulsion of the contacts are experienced, protection is entrusted to H.R.C. fuses that do not operate with currents within a limit which the contactor can withstand but that, on the contrary, with higher currents grant the full protection or a limited damage of the contactor itself. The table below shows for the different types of contactor the corresponding size of fuses recommended to obtain respectively the full protection or a damage limited to the contacts' welding.
(Table n. 6)

Contactor Type N   85 125 190 270 350 550 650 800 1000 1250
Max.Fuse c 100 125 160 225 250 355 425 500 630 1000
Rating
[Amps.]
b 125 160 200 300 355 500 630 800 1000 1200
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