MCCB: Molded Case Circuit Breaker is a type of electrical protection device which is used when the load current exceeds the limit of a miniature circuit breaker. The MCCB provides protection against overload, short circuit faults and is also used for switching circuits. It can be used for higher current rating and fault levels even in domestic applications. The wide current ratings and high breaking capacity in MCCB find their use in industrial applications. MCCB can be used for the protection of capacitor bank, generator protection, and main electric feeder distribution. It offers adequate protection whenever an application requires discrimination, adjustable overload setting, or earth fault protection.
MCB: Miniature Circuit Breaker automatically switches OFF electrical circuit during any abnormal condition in the electrical network such as overload & short circuit conditions. However, the fuse may sense these conditions but it has to be replaced through MCB can be reset. The MCB is an electromechanical device that guards the electric wires &electrical load against overcurrent so as to avoid any kind of fire or electrical hazards. Handling MCB is quite safer and it quickly restores the supply. When it comes to house applications, MCB is the most preferred choice for overload and short circuit protection. MCB can be reset very fast & doesn’t have any maintenance cost. MCB works on a bi-metal respective principle which provides protection against overload current & solenoid short circuit current.
Types of MCB: It is important to know about the types of MCB trip curves to decide what type to use for different appliances for the correct electrical system. This is the selection chart or the criteria to make a call on one of the MCBs. But before that, it is vital to understand what a trip curve means. Trip curves are essentially nothing but the maximum current that a particular MCB can withstand. Once the ideal current loading is breached, the circuit automatically cuts off.
There are about six different types of MCB, which are A, B, C, D, K, and Z. Firstly,
a. Type A, trips off the circuit when the current exceeds 2-3 times the actual current rating. Since this type is highly sensitive to short circuits, it is better suited for semiconductor devices.
b. Type B, which trips off when the current flow is 3-5 times the actual flow and finds a use for cable protection.
c. The best-suited type of MCB for domestic appliances, where the current load is medium, type C. Type C MCB trips off when the flow of current is 5-10 times more than normal.
d. Type D MCB has a high resistance as they can withstand up to 10-20 times the current rate. If you are looking for circuit breakers for devices with a high starting current load like a motor, then type D is the ideal choice.
e. The type K MCB withstands up to 8-12 times the initial charge and thus can be used for bulky load devices.
RCCB: Residual Current Circuit Breaker is basically an electrical wiring device that disconnects the circuit whenever there is leakage of current flow through the Human body or the current is not balanced between the phase conductors. It is the safest device to detect and trip against electrical leakage currents, thus ensuring protection against electric shock caused by direct contacts. RCCB is generally used in series with an MCB which protects them from over current and short circuit current. Both phase and neutral wires are connected through an RCCB device. These are an extremely effective form of shock protection & widely used for protection from a leakage current of 30,100 & 300mA. It is essential lifesaving equipment used to protect the human body from electrical and is mandatory in many states for domestic installation.
ELCB: Earth Leakage Circuit Breaker has the same function as RCCB but is a voltage sensor devise. However, this is an old technology & is not in common use. RCCB being a current sensitive device has a better advantage over ELCB.
Contractor: Contractors are electrically controlled switches (relays) used for switching an electrical power circuit. A contactor is typically controlled by a circuit that has a much lower power level than the switched circuit, such as a 24-volt coil electromagnet controlling a 220-volt motor switch.
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