Explain how the 4 pole MCB is different from Triple pole and neutral
TPN= Thripple pole + neutral. Three (Triple) contacts make and break but neutral is closed contact.
Whereas 4P (3 phases +Neutral) all 4 contacts make and break together.
TPN means Triple Pole(TP)+ Neutral(N)which is 3 phases and neutral, but the protection is given for three phases only and in 4 pole MCB protection is given to all 3 phases as well as neutral. In the case of 4 pole MCB, the purpose is not to protect the neutral but it is rather to isolate the neutral.