Circuit breaker is a switching device which can be operated manually and automatically for controlling and protecting an electrical power system. Without circuit breakers, household electricity would be impractical because of the potential for fires from simple wiring problems and equipment failures. There are mainly three types of Electrical Circuit Breakers:
Miniature Circuit Breaker (MCB):
The Miniature Circuit Breaker is shortly termed MCB. It is a precision electrical cum mechanical safety device for the protection of an electrical circuit against short circuit and overload conditions.
The Miniature Circuit Breaker comes into action when the circuit current exceeds the maximum rated value of current and disconnects the electric supply line and thus saving the supply line from any sorts of fire hazards. The MCB can be used for the protection of the whole electrical installation as well as in the individual circuits protection.
For individual circuit protection, MCB will perform the duties of fuses in the main distribution board. MCB can be used in motor installation circuits as backup protection. The MCB can be available in 240 volts as well as 415-volt ratings. The current ratings are available 10A, 16A, 20A, 25A, 32A & 63A. Besides these low current ratings are also available in the market are 1A, 2A, 2.5A, 5A, etc. The operating current of a Miniature Circuit Breaker is 125% of the rating of the MCB.
Residental Circuit Breaker (MCB):
RCCD is a protection of the electrical installation. It is also termed Leakage Current Circuit Breaker (LCCB). This type of protection device is normally used for giving protection against fire hazards and electric shock. The leakage current flows through to the earth causing a fire.
As the intensity of the leakage current is very small, which will be unable to blow up the fuse and not be possible to operate the miniature circuit breaker. In that case, RCCB will operate to save the installation from damage. For the detection of the installation’s leakage current the residual current circuit breaker. Utilised the principle of current transformer of core balance type. The voltage rating of this type of circuit breaker is 240 volt/415 volt and current ratings are 16A, 20A, 32A & 48A.
Earth Leakage Circuit Breaker (MCB):
ELCB is extensively used in a medium voltage electrical installation. As an earth leakage circuit breaker is a safety device used in electrical installation with high earth impedance to prevent electric shock. ELCB interrupt the circuit if it detects a small number of stray voltages on the metal casing and enclosures of the electrical equipment.
With a connected load of approximately SKW and above, the connection of the earth leakage circuit breaker is a compulsory duty as per Indian electricity Rules. If the death leakage current flows then disconnect the electric supply instantly. The main purpose of earth leakage protectors is to prevent injury to humans and animals due to electric shock. There are mainly two types of ELCB:
i. Voltage Operated ELCB: A voltage-operated ELCB detects a rise of potential before the protected inter-connected metallic structure such as conduit, enclosures etc and a distant isolated earth electrode. The earth circuit is modified when ‘ELCB’ is used, the connection to the earth wire is passed through the ‘ELCB’ by connecting to its two earth terminals.
ii. Current Operated ELCB: Current operated ELCB gives protection against earth leakage using a different method of detection. It is also called Residential Current Device. Some reputed organizations use the term ‘ELCB’ to distinguish high sensitivity current operated 3 phase devices that trip in some milliampere range from the traditional 3-phase ground of earth fault devices that operate at much higher currents. The ELCB detects fault current from life to the ground wire within the electrical installation it protects.