Thursday, 19 October 2017

What is MCB & How it Works?


MCB refers to (Miniature Circuit Breaker) is a device which protects the electrical system from the abnormalities due to overcurrents and protects the load connected to the system.
Now da days various ranges of MCB’s are used from 6A to 16KA in Various domestic, Commercial and Industrial Sectors.Sometimes MCB’s can be called as switches due to the ON/OFF operation, The switching has to be done by manually; under a faulty condition, the switch or the operating lever will trip automatically and after fault cleared the operating lever has to bring normal by manually.


The electromechanical device has 2 arrangements;
1.Thermal
2.Magnetic
The Thermal arrangement of the MCB is to protect from OverTemperature Faults, it has bimetallic strips which in turn actuates the contactor or latch to trip the supply.Generally, bimetallic strips are made from Brass and steel.Under the Faulty condition, the bimetallic strip got heated and bend from one side to other due to the difference in temperature and in turn trip the latch.The MCB while tripping will create arcs in order to suppress the arc the Arc Runner and Arc Splitter employed, below is the illustration.

                    
The Magnetic Arrangement of the MCB works when an overcurrent detected the solenoid get magnetized and in turn trip the latch to protect from the overcurrent.Once the contactor got separated the arc will produce and it will pass to arc runner and finally quenched after arc splitter(arc chutes), The arc chute consists of series of chambers which will cause the arc to split and losses the energy.
The MCB’s are made for different pole ranges from single, double, triple and four pole variants as the application demands.The tripping current capacity of the device also varies for a different application.
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