Maximum No. of Trips

Depends on the current broken doesn't it?

At max short circuit current I_cu, an MCCB or ACB can do only two : one break shot and one make/break shot. At rated current, it may do thousands of operations.

When the CB opens, how do you know whether the current broken is I_cu, I_cs, I_n, 0 ... what?

Call the manufacture, they can advise you.

This is extremely controversial - many manufacturers will not quote you (particularly MCCBs which are built down to a price). I have experience years ago where Rockwell were asked this question, from someone who really wanted fuses. They did some tests on some MCCBs, at 50kA prospective (Icc) and tripped several different types 10 times in succession (Same MCCB each test). All passed. This was using our enclosures, and I have the certificates.

I have also seen an MCCB from another manufacturer destroyed completely on the first test (i.e. it tripped, cleared the fault, then died). Get the test certificates from the manufacturer, or replace after every major trip.

How do you know how big the fault? You probably don't unless you have expensive electronic trip units that can record it.

Exactly my point. i trust fuses more. Every time one blows, the new one is capable of whatever the max fault level, maybe 200kA. Not so CBs. But then, this is a debate going on for decades. So, when i am involved in the design of MCCBs, i try my best to do as good a current-limiting design as possible. Most of it has been done already by outstanding engineers in good companies....

This is something that the manufacturers are often very coy about, you probably won't find it specified in their technical documentation.

The standards regime in my part of the world for MCBs specifies that an MCB must be able to break 3 faults at the maximum rated fault current. This does not mean that it will still be good to go after those 3 trips, it will almost certainly need to be replaced. The markings on said MCB will include maximum fault current [6000] and underneath is [3], which reflects this.

What I get from a french manufacturer is

MCB small ones for full rated fault current 2--3

after that you will not be able to use them

For MCCB with trip units the detection is energy based so they disconnected before all that region but it is more then over load so safe side is 1000 .

also they mention type 1 and type 2

"For MCCB with trip units the detection is energy based so they disconnected before all that region but it is more then over load so safe side is 1000 ."

You are making a dangerous wrong assumption. In current-limiting MCCBs, there is no time for a trip unit to sense and act. The MCCB trips due to Reflex action, much like knee-jerk. With this extremely rapid trip, it may clear the fault in as low as 2 milliseconds. With this rapid tripping ability, it is still capable of only 3 shots O-CO or, at best, 5 shots O-CO-CO. Not 1000 for sure. Do not let the salesmen con you.