mccb over heating &noisy

MCCBs tend to be very reliable, but it could be an internal fault with the MCCB contacts. If you were to tell us the manufacturer of your MCCB, this would help in assessing just how likely this is.

My own experience is with GE MCCBs, and I have yet to see one overheat due to an internal fault, but other brands may have this problem.

I suggest checking the terminals. The only instances that I have seen of overheating was where one of the terminals has not been tightened sufficiently onto the cable lug. This melted the case around one terminal.

If it is not clear just where the source of the heat is, an infrared scan of the MCCB should easily pinpoint it.

pl. check the ambient temperature where the MCCB is installed.It should be within 45 Dcentigrade.

If there is noise, then it must be chattering of MCCB contacts. check voltage across the same terminals. The voltage drop should be Zero. If there is any voltage drop, then it is better to change the MCCB. can validate the controls also.

The reason?

It's knackered!

Replace it with a new one.