eot presentation for mcbs

8/9/2019 EOT Presentation for MCBs

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MINIATURE CIRCUIT

BREAKERS .

SUBMITTED TO :

MR. SHAKEEL IQBAL

SUBMITTED BY :

VAISHNAVI SINGH

MAHAK RAITANI

KAJAL KUKI PATWARI


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Unlike a fuse, which

operates once and then has

to be replaced, a circuitbreaker can be reset (either

manually or automatically)

to resume normal operation.

Circuit breakers are made invarious sizes, from small

devices used to protect an

individual household

appliance up tolarge switchgeardesigned to

protect high voltage circuits

to supply an entire city.

A FUSE

A CIRCUIT

BREAKER


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TYPES OF CIRCUIT

BREAKERS

Types of Circuit breakers as follows:-

MV(medium voltage circuit breakers) :

MVs are operated by current sensingprotective relays operated through current

transformers.

They are further divided into:

1.Air Circuit Breaker (ACB)2.Vaccum Circuit Breaker (VCB)

3.Oil Circuit Breaker

4.SF6 Circuit Breaker


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LV(low voltage circuit breakers) :

Low voltage (less than 1000 VAC) types arecommon in domestic, commercial and

industrial application, and include:

1.Air Circuit Breaker (ACB)2.Moulded Case Circuit Breaker (MCCB)

3.Earth Leakage Circuit Breaker (ELCB)

4.Miniature Circuit Breaker (MCB)

5.Motor Protection Circuit Breaker(MPCB)


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HV(high voltage circuit breaker) :

High-voltage breakers are nearlyalways solenoid-operated, with current

sensing protective relays operated

through current transformers. They include:

1.Bulk oil

2.Minimum oil

3.Air blast

4.Vacuum5.SF6


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THREE POLE COMMON TRIP BREAKER FOR SUPPLYING A

THREE-PHASE DEVICE. THIS BREAKER HAS A 2 A RATING


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MINIATURE CIRCUIT

BREAKERS

MCB means Miniature Circuit Breaker which

are small capacity ( low voltage ) breakers and

these too are moulded . So MCB is a breakerbut moulded (sealed). The breaker is the term

used to a unit which breaks (opens) the circuit

above its rated flow of current. It has the

characteristic and ability to self operate andisolate (break) the circuit if there is a fault

down the line.


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Miniature circuit breakers (MCBs) are fitted

in newer consumer units in place of fuses.

They have the advantage that they can bemanually reset without having to replace wire

as in the case of the traditional fuse.

The MCBs have either a button or lever that

can be flicked to reset it.The MCB tripping is an indication either

that the circuit has been overloaded or that a

short circuit has occurred somewhere in thesystem


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Before resetting the MCB

it is important to identify

what has caused it to trip.First switching off the

main switch on the

consumer unit is very

important.Reset the MCB by either

pushing the button or by

flicking the lever.Finally flick the mainswitch of the consumer

unit back on.If the MCB immediately resets itself once

power is restored, a fault is still occurring..


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WHY ARE MCBs

IMPORTANT??

The miniature circuit breaker is an absolutely

essential device in the modern world, and one of

the most important safety mechanisms in your

home. Whenever electrical wiring in a buildinghas too much current flowing through it, these

simple machines cut the power until somebody

can fix the problem. Without circuit breakers (or

the alternative, fuses), household electricity

would be impractical because of the potential for

fires and other mayhem resulting from simple

wiring problems and equipment failures.


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A MINIATURE

CIRCUIT BREAKER


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HOW DO MCBS WORK??

The basic idea behind a circuit breaker is to

create a switch that will automatically turn

itself off if too much current flows through it. The most common way to accomplish this is to

use an electromagnet.

When too much current flows through the

electromagnet, it generates enough magnetic

force to trip the circuit breaker and cut the

power.


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MINIATURE CIRCUIT

BREAKER

1.Cable terminals

2.Bi-metal thermo

element

3.Contacts4.Arc chamber

5.Solenoid

6.Operating handle - used

to manually trip andreset the circuit breaker.

7.Din rail mounting.


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CONSTRUCTION

BREAKER DESIGN: BASIC

The basic circuit

breaker consists of a

simple switch,connected to either a

bimetallic strip or

an electromagnet.

The diagram shows atypical electromagnet

design.


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The hot wire in the

circuit connects to the

two ends of the switch.When the switch is

flipped to the on

position, electricity can

flow from the bottomterminal, through the

electromagnet, up to the

moving contact, across

to the stationarycontact and out to the

upper terminal.


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The electricity magnetizes the

electromagnet . Increasing current boosts theelectromagnet's magnetic force, and

decreasing current lowers the magnetism.

When the current jumps to unsafe levels, the

electromagnet is strong enough to pull downa metal lever connected to the switch

linkage. The entire linkage shifts, tilting the

moving contact away from the stationary

contact to break the circuit. The electricityshuts off.


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BREAKER DESIGN:

ADVANCED

One of the newer

circuit breaker devices

is the ground fault

circuit interrupter,or GFCI. These

sophisticated breakers

are designed to protect

people from electricalshock, rather than

prevent damage to a

building's wiring4-OUTLET GFCI

POWER BOX


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APPLICATIONS

Miniature circuit breakers are designed foruse in residential and light industrial

settings.They are electrical devices that regulate the

flow of electricity in order to protect peopleand equipment from the effects of power

surges or overloads.The breakers operate in one of three

positions: on, off, or tripped. In the tripped

mode, the breaker interrupts the flow of

electricity in order to protect the system.


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eot presentation for mcbs

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