As learnt in previous article, we use electric fuse as a safety device which is connected in series with the live wire which carries current. Excess current flowing through fuse wire gets heated up and melts immediately, which disconnects the main circuit that carrying current and we could save electric appliances from getting damaged. The fuse blocks all the input current and we face outage of electricity. Then we need to replace the fuse wire, only then restoration of electricity is possible, which is little bit tedious, hectic and time consuming process. Hence to avoid this inconvenience, alternative for electric fuse is used known as MCBs i.e. miniature circuit breaker, which too works on heating effect of electric current. You may have seen the following device fixed on wall which is shown in picture.
Miniature circuit breaker is a device which acts as an automatic switch when current flowing through the metals strips inside it is exceeded the permissible value. It has automatic shutting mechanism known as ‘tripping’. It does not contain any wire like fuse, but its working is also based on heating effect of electric current. The advantage of MCB over fuse is that it can reset to normal just by pulling/pushing the switch ON, unlike the fuse in which restoration can takes place only after replacing the fuse wire. Some of important advantages/importance of MCBs is as below.
- It automatically switches off the circuit during any unexpected/excess condition of current, or fault in the network.
- MCBs can be used separately for each portion of house, so that if any one among all the circuit has fault, tripping will takes place for that part of circuit only, so that the remaining part can work without any outage of electricity.
- It is more sensitive and reliable than fuse.
- It low/high voltage it works finely which gives surety for safety at all circumstances.
- Quick restoration of electricity can be achieved just by switching it ON.
Q. What is the principle of working of MCBs?
Ans: It works principle of heating effect of electric current.
Q. What are miniature circuit breakers?
Ans: Miniature circuit breaker is a device which acts as an automatic switch when current flowing through the metals strips inside it is exceeded the permissible value.
Q. On which mechanism MCBs work?
Ans:MCBs has automatic shutting mechanism known as ‘tripping’.
Q. State any two advantages of MCBs over electric fuse.
Ans: It is more sensitive and reliable than fuse.
It low/high voltage it works finely which gives surety for safety at all circumstances.
Quick restoration of electricity can be achieved just by switching it ON.