Breaker Explanation

4 x 20A -> 4Pole 20Amps

mg curve C -> Magnetic trip CURVE C

PCC 10KA-> its prospective short circuit current capacity (breaking capacity) .It is the important factor to be considered when choosing an MCB and this must always be greater than the prospective short-circuit current (PSCC) at the point where the MCB is installed.

What is the difference between Curve C and Curve D

the difference is in operating range of their magnetic trip unit. Its 3-5 times the rated nominal current (In) in B curve, 5-10 times in C curve & 10-14 times in D & K curve, 2.4-3.6 in Z curve, 9.4-14.4 times in MA trip curve.

detailed info.

Type B MCBs react quickly to overloads, and are set to trip when the current passing through them is between 3 and 4.5 times the normal full load current. They are suitable for protecting incandescent lighting and socket outlet circuits in domestic and commercial environments, where there is little risk of surges that could cause the MCB to trip.

Type C MCBs react more slowly, and are recommended for applications involving inductive loads with high inrush currents, such as fluorescent lighting installations. Type C MCBs are set to trip at between 5 and 10 times the normal full load current.

Type D MCBs are slower still, and are set to trip at between 10 and 15 times the normal full load current. They are recommended only for circuits with very high inrush currents, such as those feeding transformers and welding machines.

for more on trip curves download this software from Schneider electric

schneider trip curves

While I appreciate your explanation to the question, I fear your detailed infor on B, C & D MCBs isn't correct. It is mentioned that Type B MCBs are set to trip between 3 to 5 times the rated current. Does that mean that these MCBs would not react fore overloads. The statement should have been "set to trip 'instantaneously' when the current is 3 to 5 times the ratec current".

And, it is also mentioned that Type C & Type D MCBs are slower. Please note that as per IEC, there no change - I repeat - no change, in the overload charecteristic curves of all these three type sof MCBs and as such all three would behave exactly in similar manner for a given overloda.

The difference, then, is in their instantaneous or magnetic trip current settings, which is correctly mentioned by you.