MCB (MINIATURE CIRCUIT BREAKER)
Miniature circuit breakers have precision formed moulded case and cover of flame retardant high strength thermo plastic material having high melting point, low water absorption, high dielectric strength and temperature withstand.
The switching mechanism is independent, manual, and is trip free, i.e. breaker trips internally even if the operating knob is held on position.
The Arc-Extinguishing device comprises of 15 plates arc chutes\. The arc under the influence of the magnetic field and arc guide is moved into the arc chute where it is rapidly split and quenched.
The tripping mechanism is Thermal Magnetic type.
Thermal operation provides protection from moderate overloads. Under over load condition a thermo metal element (bimetallic strip) deflects until it operates a latching mechanism allowing the main contacts to open.
Magnetic operation, large overloads or short circuit current actuates a solenoid causing a plunger to strike the latching mechanism rapidly opening the main contacts.
The Fault current breaking capacity -9KA. They may be used instead of fuses on individual circuits and are usually backed-up by fuses in the main feed to the distribution board.
Selection chart for house hold appliances-
Oven cum griller
Hot plate/room heater