how to trip a MCB without short circuit or over load?
Anything that you do to the inside of the circuit breaker will either jeopardize or destroy at least some of the normal function of the MCB. Even just opening the case makes the future function of the MCB questionable.

You could conceivably use an external solenoid to push the lever.

You could connect a relay in series with the circuit breaker.

You could buy a circuit breaker with a built-in shunt-trip mechanism, but that would be a molded case circuit breaker that would be larger and more expensive.


  can you plz provide a circuit of "shunt trip coil"?


The trip coil shown in the picture could be converted to a shunt trip coil by disconnecting it and providing a new path for current through the thermal trip element. Then the 5 turns of heavy wire would need to be removed and replaced with many more turns of smaller wire. It you want to trip the breaker by supplying 2% of the present magnetic trip current, you would divide the original number of turns by 0.02 and use about 250 turns. The trip current multiplied by the number of turns needs to remain about the same.