They are there to protect the WIRING. To protect the motor, use a motor overload protective device as well.
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"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
To protect your load motor you should use an overload for protection and not MCB or MCCB.
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Management is just like a bunch of Monkey sitting on a tall tree. Some climb to the highest branch and some at the lowest branch. The highest Monkey look down and see a lot of happy faces but the lower Monkey looks up and see nothing but all the....