The rod in the circuit breaker is connected. The trip coil will be energized and it will start working like a magnet. The relay will sense that faulty current occur the relay coil will make mmf this coil work like a magnet it will pull the relay contacts and the joints will be close. When the faulty current occur the current in the primary coil of current transformer will be increased due to which current in secondary coil of current transformer will also be increased. For example we have 100A of current in the line of primary coil of current transformer while the relay operate on 5A current then the current transformer will convert 100A current to 5A current through secondary coil the relay will get 5A. The current transformer converts high current in low current. Now let us consider the above diagram in which current transformer is connected with circuit breaker. To remove this arc we use circuit breaker. This arc is dangerous for circuit if it is in huge amount. The medium oil or air which is present between them their ions will be ionized which will create conducting path due to which arc will be developed. When faulty current produce the moving contact trap energized moving contact separate from fix contact the area will be reduced due which its current density will be increased and heat will be generated due to which radiation will be produce. The moving contact is connected with fixed contact. A few days back I posted an article about “ electric motor tripping”, which explains the practical use of a circuit breaker with common issues solved.Ĭircuit breaker consists of two contacts one fixed and other is moving contact. When the fault in the system is removed it will be simply switched on they do not require replacing and can simply be reset. Circuit breaker operates automatically by measuring heat or current flowing through the circuit if the current exceeds a pre-set limit, the circuit breaker will ‘trip’ and sever the electricity supply as quickly as possible it will disconnect the electricity load. Difference between MCB and MCCB circuit breakersĬircuit breaker is very useful equipment for switching and protection of various parts of power system.Difference between fuse and circuit breakers:.Auxiliary switches for remote monitoring and/or control. A shunt trip coils that enabling remote tripping. By virtue of that a good discrimination can be achieved with accuracy about ☑0%.Įventually, MCCB/ICCB has advantages in the capability of accommodating further features which can be provided as The advent of electronic protection increased the use of them and the scope is widened like tolerances, range of time & current adjustment. MCCB and ICCB are almost the same and both are manufactured in accordance to NEMA AB1/AB3 to suit industrial and commercial purposes. MCCB – Molded Case Circuit Breaker & Insulated Case Circuit breaker are also current limiting devices but with high making/ breaking capacity and current ratings compared with MCB. MCBs available in different number of poles (SP, DP, TP,). Ii- MCB is of low breaking / making capacity as well as low current rating compared with MCCB/ICCB. Type D is suitable for application where a high in-rush current is expected. Type C is used in commercial & industrial applications. I- MCB is basically made in accordance to BS 3871, is now superseded by BS EN 60898 which recognizes type B, C & D. Used to protect final circuits from O/C such as Overload & Short Circuit. MCB – Miniature Circuit Breaker is suitable for domestic usage. It is operating characteristic addressing the overload by thermal action of the bimetal strip and instantaneously dealing with short circuit occurrences by electromagnetic action. Are defined as “Thermo-magnetic “ CBs, accordingly. The arc created by breaking contacts is extinguished in an arc chamber. MCB and MCCB/ICCB have a bimetal heater for overload which releases the Contact s while for short circuit the trip / electromagnet hammers itself against moving contacts. The aforementioned types of Circuit Breakers are used in LV System and generally based on the same operating principle.