eot presentation for mcbs
Post on 02-Jun-2018
238 Views
Preview:
TRANSCRIPT
-
8/9/2019 EOT Presentation for MCBs
1/20
MINIATURE CIRCUIT
BREAKERS .
SUBMITTED TO :
MR. SHAKEEL IQBAL
SUBMITTED BY :
VAISHNAVI SINGH
MAHAK RAITANI
KAJAL KUKI PATWARI
-
8/9/2019 EOT Presentation for MCBs
2/20
-
8/9/2019 EOT Presentation for MCBs
3/20
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
-
8/9/2019 EOT Presentation for MCBs
4/20
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
-
8/9/2019 EOT Presentation for MCBs
5/20
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)
-
8/9/2019 EOT Presentation for MCBs
6/20
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
-
8/9/2019 EOT Presentation for MCBs
7/20
THREE POLE COMMON TRIP BREAKER FOR SUPPLYING A
THREE-PHASE DEVICE. THIS BREAKER HAS A 2 A RATING
-
8/9/2019 EOT Presentation for MCBs
8/20
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.
-
8/9/2019 EOT Presentation for MCBs
9/20
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
-
8/9/2019 EOT Presentation for MCBs
10/20
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..
-
8/9/2019 EOT Presentation for MCBs
11/20
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.
-
8/9/2019 EOT Presentation for MCBs
12/20
A MINIATURE
CIRCUIT BREAKER
-
8/9/2019 EOT Presentation for MCBs
13/20
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.
-
8/9/2019 EOT Presentation for MCBs
14/20
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.
-
8/9/2019 EOT Presentation for MCBs
15/20
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.
-
8/9/2019 EOT Presentation for MCBs
16/20
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.
-
8/9/2019 EOT Presentation for MCBs
17/20
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.
-
8/9/2019 EOT Presentation for MCBs
18/20
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
-
8/9/2019 EOT Presentation for MCBs
19/20
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.
-
8/9/2019 EOT Presentation for MCBs
20/20
top related