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Saturday, 21 April 2012

MCB

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
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.
                                   

Colour identification-

Knob colour
Series name
Application
GREEN
L
Lighting
BLUE
G
Motors
BLACK
DC
DC circuit
RED
Isolator
Isolation


Selection chart for house hold appliances-

Application
Watt, 230V,AC
MCB rating
Series
Air conditioner
1.0 tonnes
1.5 tonnes
2.0 tonnes
10A
16A
20A
G’Series
Refrigerator
165 litre
350 litre
3A
4A
G’Series
Oven cum griller
1750W
4500W
10A
32A
L’Series
Hot plate/room heater
750W
1000W
2000W
6A
6A
10A
L’Series
Washing m/c
300W
1300W
2A
8A
G’Series
Water heater
1000W
2000W
3000W
6000W
6A
10A
16A
32A

L’Series
Electric iron
750W
1250W
6A
8A
L’Series
Toaster /kettle
1200W
1500W
8A
10A
L’Series






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