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elcb and rccb

                                    ELCB AND RCCB

ELCB : (EARTH LEAKAGE CIRCUIT BREAKER) 


        The ELCB, which normally operates based on voltage, is a simple ELCB.  The way the Voltage ELCB works is simple.  A terminal of the Relay coil is attached to the metal body of the equipment to be protected.  Next to Relay Coil. If any insulation fails, or the phase wire in the electric supply touches the metal body of the equipment, a voltage difference occurs between the relay coil connected to the equipment and the earth.  When this voltage difference exceeds a certain limit, the relay coil becomes larger and the relay becomes operable.  So the circuit breaker attached to the relay operates and disconnects the supply to the equipment.

RCCB : (RESIDUAL CURRENT CIRCUIT BREAKER) 


        Residual current circuit breaker is more sensitive than ELCB.  The ELCB, based on the current, is called the RCCB. it contain 2 primary windings and 1 secondary winding which is connected to relay . The phase and neutral residual flux are normal in the normal condition.  The resultant flux caused by these two co-efficients is zero, since both are equal and opposite.  So no passes through the secondary winding of the CT.  Thus the relay attached to the secondary winding of the CT will not operate.

        In the event of a earth leakage current in the instrument, the partial current of the phaser span passes through the leakage path to the earth instead of the neutral. now the resudual flux in upper primary winding and lower primary winding will become unequal to the phase current.  So a resullant flux occurs in the core of the CT.  This causes a current flow  in the secondary of the CT.  So the relay operate connected to the secondary of the CT and trip the circuit breaker.  

TEST CIRCUIT :

        To test the RCCB, a test tag is attached.  This test circuit is on the load side with the line conductor and the supply side.   The current goes through the test circuit.  The size of this current depends on the resistance that is set in the circuit.  The current passes through the phase side coil along with the load current. That is, bypass.  Therefore the current passing through the RCCB's phase side and the neutral side is not equal.  So RCCB trips the supply even at normal.

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