Answer / nidal rafeeque

Specifically, these curves denotes the instantenous
tripping current, if fault current crosses the designated
mark.

B : 2-5 times the rated current.
C: 5-10 " " " "
D : 10-15 " " " "


C- curves type are used for heavy currents in normal
working.(e.g. Heaters, Gyesers, Irons)

D-curves types are used for heavy inrush currents.(Motors
etc)

Answer / antu paul

B,C,D Curves are characterised with instantaneous trimping
current and is as below
for B curve-above3*In-upto and include 5In
for C curve-above5In upto and include10In
for D curve-above 10In upto and include 20In
for Z curve 8In-12In for inductive loads
K curve for semiconducting devices

where In is the rated current of MCB.

Answer / raja

These curves denotes the instantaneous value of current

C curve is 5-10 times of rated current and D curve is 10-15
times of rated current.D is normally used with motor.

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