When should I use fuse , mcb(b,c,d,k) tybes , mccb ?

Fuse is old technology to break d circuit in fault. MCB is for low fault currents starting 6Amps to, 63Amps either 1Phase or 3Phase. And (b,c,d,k) are depends on the fault current and the location u r going to use. MCCB for higher currents more than 63 Amps that to in 3 Phase only.

MCBs have relatively low breaking capacity and sluggish compared to fuse. Fuse is used when cost of cable is a factor. If MCBs are used proper cable sizing must be done considering fault level and duration.