Breaking capacity and melting I²t — the real selection numbers
The 1206SFF075F/63-2: The 50 A breaking capacity at the rated 63 VDC means the fuse can safely interrupt a fault current up to that level without rupturing or sustaining an arc — critical for DC bus protection where the available short-circuit current can exceed the fuse's interrupt rating. The cold resistance of 0.513 Ohms and melting I²t of 0.0052 A²s define the inrush energy the fuse absorbs before opening. A downstream capacitor bank charging through this fuse must stay below that I²t budget, or the fuse will nuisance-blow on power-up.