COMPARISION BWTWEEN MCB, ELCB,
RCCB, RCBO & RCD
Type of protection |
MCB |
ELCB |
RCCB |
RCBO |
RCD |
Over-current |
yes |
no |
no |
yes |
no |
Short Circuit |
yes |
no |
no |
yes |
no |
Earth Fault |
no |
yes |
yes |
yes |
yes |
S.No |
MCB |
MCCB |
1 |
It stands for
Miniature Circuit Breaker. |
It stands for
Molded Case Circuit Breaker. |
2 |
Rated current not
more than 125 Ampere. |
Rated Current up
to 1600A |
3 |
Its interrupting
current rating is under 10KA |
Their
interrupting current ranges from around 10KA -85KA |
4 |
Judging from
their power capacities, MCB is mainly used for low Breaking capacity
requirement mainly domestic. |
MCCB is mainly
used for both low and high Breaking capacity requirements mainly industrial. |
5 |
Its trip
characteristics are normally not adjustable since they basically cater to low
circuits. |
Its trip current
may be fixed as well as adjustable for overload and magnetic setting. |
Difference between RCCB and
ELCB
S.No |
RCCB |
ELCB |
1. |
RCCB refers to
ear stands for Residual Current Circuit Breaker. |
ELCB stands for
Electric Leakage Circuit Breaker. |
2. |
It is a new name
and refers to current operated devices. |
ELCB refers to
voltage operated earth leakage device. |
3 |
It ensures 100%
detection of leakage current& is available to sense the AC as well as DC
leakage current. |
It is not
preferable as it can only detect current that flow back through the main
earth wire. |
4 |
RCCB has no
connection with the earth wire and that’s why it can trip when both currents
(phase and neutral) are different and it withstands up to both the currents
are same. |
ELCB is working
based on Earth leakage current. These devices measured the voltage on the
earth conductor; if this voltage was not zero this indicated a current
leakage to earth. |
Difference between MCB, MCCB,
ELCB, RCCB and RCD
The MCB, MCCB, ELCB, RCCB and RCD are more often
controversial most of the time to select from and to install in homes,
commercials or instead industries too, and the reason is simple as neither the
user nor the electrical contractor knows their difference precisely, resulting
in investing money in an excellent electrical installation without enjoying
it’s right functioning, making user vulnerable to electrical shocks, fire
hazards, dark outs, and malfunctioning of electrical gadgets.
Difference between MCB, MCCB, ELCB, RCCB
and RCD
The worst occurs when after installation some
incompetent person tries to fix them, with his experience or little knowledge,
gathered from here and there without any academic learning of how these gadgets
operate, and why they trip and create a nuisance.
The circuit breakers are otherwise designed to break
and extinguish the arc safely flowing at the breaker terminals to prevent any
sparking at the terminals or fire in the circuit breaker while disconnecting
the supply from the live load.
Here, we will discuss them threadbare in the most
convenient way to read them and understand their terminology
What are these MCB, MCCB, ELCB, RCCB and
RCD called?
All these electrical gadgets belong to electrical
circuit breaker category to connect the incoming electrical supply to equipment
during regular operation and to immediately provide protection to personnel,
equipment and the entire electrical installation from malfunctioning, damage,
electrical shock, or even fire by disconnecting the electrical supply from the
equipment by triggering the inbuilt protective system in them depending upon
the nature of the fault.
Depending upon the cause and the nature of the fault
different circuit breakers operate in the installation at different places
whether the localized one that is directly connected to the equipment or the
one that is connected close to the incoming supply to take care of the entire
electrical installation. Here follow their descriptions –
MCB –
Miniature Circuit Breaker
MCCB – Moulded Case Circuit Breaker
ELCB –
Earth Leakage Circuit Breaker
RCCB –
Residual Current Circuit Breaker
RCD –
Residual Current Device
These circuit breakers are installed at
different-different places in the electrical installation for specific
applications depending upon the type of protection required.
What is Short Circuit?
A short circuit occurs when two or more wires
supplying electrical supply to the equipment come in contact with each other
making the current flow from the unintended path.
In other words when the phase and neutral wire come
in direct contact with each other without any load connected in between them,
it leads to short circuit.
During normal operation, the current flows from one
wire say ‘Phase’ and returns through the other wire say ‘Neutral’, after
supplying the required voltage to the equipment connected in between these two
wires.
What is Short Circuit?
Why Short Circuit Occurs?
When the two wires Phase and Neutral come in contact
somewhere on the way or get shot, the point of contact at the short wire
provides a low impedance path to the current resulting in an excessively huge
current immediately flowing through the system with a potential to damage the
equipment in addition to blazing the electrical system as well as damaging and
blazing the equipment.
Therefore, short circuit protection is a must to all
electrical gadgets without distinction or segregation.
How does Short Circuit Protection work?
Short Circuit is immediately realized by a
magnetically operated protective system (solenoid), which trips the MCB without
fail in a fraction of second or the scheduled time specified by the
manufacturer or as per the settings are done on the MCB to operate.
What would happen in case the short
circuit protection doesn’t work?
Immediate Fire! The excessive current would lead to
sparking and direct fire in the electrical system and the equipment within a
second without giving any chance to operate the protection manually.
And, above all the fire will not get restricted to
the concerned equipment or circuit but will immediately get into nearby
surroundings and remaining electrical system as these wires are highly
combustible.
What is Overload?
Electrical circuits and equipment are designed to
handle a specific range of current and voltage at a particular frequency.
When equipment draws heavy current due to any
reason, it is termed as overloading of the equipment and the system.
Why Overloading Occurs?
When the electrical equipment is made to work more
than specified as per their manufacturing, they start drawing a heavy current
depending upon the nature of the equipment and creates electrical stress on the
electrical system as well as the equipment itself.
This electrical stress leads to deterioration of
equipment as well as wiring insulation, causing insulation rupturing anywhere
in the circuit leading to either earth leakage fault or even a short-circuit
fault.
This fault can lead to severe electrical shock or
even fire, if not appropriately protected to trip the incoming electrical
supply.
No doubt, overloading takes a considerable time
depending upon the equipment, and the application varying from 30 minutes to
few hours but is equally dangerous as short circuit discussed earlier, though
not that instant.
How can overloading be detected?
Broadly, the overloading can be detected in advance
before it reaches the triggering level to trigger the protection. The four
significant conditions or warning signs can easily realize the overloading.
Flickering
of Lights – The flickering of light could be because of overloading of the
equipment or the lighting circuit whose rating is generally kept lower than the
sockets or the wiring supplying the equipment.
Burning
smell – The insulation while deteriorating at a higher temperature caused by
overloading causes a burning smell either from the equipment or the wiring
supplying power to the equipment.
Malfunctioning – At higher temperature, the equipment starts
malfunctioning in one way or the other, for instance, the motors start creating
a different louder noise than usual.
Unusual
tripping – The unusual tripping of protective system signals overloading of the
circuit as the protection tries to disconnect the equipment from the electrical
supply
How does overload Protection work?
The overload protection works on the thermo
electrical effect wherein a bimetallic strip bends. It triggers the overload
protection depending upon the excess current that builds extra voltage at the
protection mechanism.
What would happen in case the Overload
doesn’t work?
In case the overload protection fails to operate, it
could lead to fire or even a short circuit.
What is MCB?
MCB, defined as the Miniature Circuit breaker, is
the most prominent protection almost used by all. It is an electromechanical
device that guards the electrical circuit against Short Circuit, System
Overloading beyond installed capacity or Imperfect Design of the equipment
itself.
For convenience it can be assumed as a replacement
of traditional fuse used to install earlier which need to change whenever there
is a fault no matter whatsoever, thus adding to cost every time there is a
fault in the system.
While on the other hand, the MCB doesn’t require to
be changed whenever there is a fault rather requires a simple switching ON
after rectifying the present fault in the system. Even a kid can handle it
under your supervision or guidance.
What type of protection does MCB provide?
MCB provides Short circuit protection and Circuit
Overloading protection in addition to switching ON and OFF manually as and when
required during normal functioning while going for some modification or
rectification in a particular circuit guarding a specific gadget or group of
small equipment.
How are MCBs rated?
MCBs are available in the different number of poles
depending upon the application and the requirement. They could be single pole,
double pole, triple pole & four poles with neutral poles if desired. Their
rating varies from 0.5-63 A with a short circuit breaking capacity of 3-10 KA
at 230V or 240V.
What are the Characteristics of MCBs?
The MCBs come in three different characters –
The rated
current of the MCB should not be more than 100A rather 63A is a safe figure. The MCBs are usually designed for specific
ratings and are not adjustable to make their protection suitable for different loads.
The MCB usually come with a bimetallic strip to trigger the overload protection
and a magnetic solenoid to trigger the short circuit protection.
What is an MCCB?
The MCCB is also an electromechanical device,
similar to an MCB with a difference that it is designed for higher current
ratings and come with an adjustable protection system making them suitable to
work on different current ranges as per the adjustment made by turning the knob
provided on them.
What type of protection does MCCBs provide?
Similar to MCBs, the MCCBs provide short-circuit and
overload protection, which can be adjusted as per the requirement and the
application connected to it.
How are MCCBs rated?
MCCBs protect the electrical system from 63A to
3000A.Their rating varies from 63A-3000 A with a short circuit breaking
capacity of 3-10 KA at 230V or 415V.They could be single pole, double pole,
triple pole & four poles with neutral poles if desired.
What are the Characteristics of MCCBs?
The MCCBs can be operated manually, or automatically
from remote locations; otherwise, they get operated during fault conditions
when the fault current triggers their protection mechanism. Like MCBs, they
also come with Short-Circuit and Thermal Overload protection.
What are the Characteristics of MCCB?
The MCCBs comes with the following main
characteristics –
The rated
current of the MCCB should not be more than 3000A rather 2500A is a safe
figure.
The MCCBs
are usually designed for specific ranges and are adjustable to make their
protection suitable for different loads
The MCCB
usually come with a bimetallic strip to trigger the overload protection and a
magnetic solenoid to trigger the short circuit protection.
For highly
sensitive loads, the MCCBs with electronic protection is also available.
What is an ELCB?
The ELCB stands for Earth Leakage Circuit Breaker
and protect from Electrical current leakage. The ELCBs are installed in the
electrical systems as high Earth impedances to avoid electrical shock. They
detect the stray voltage on the body of the ELCB and interrupt the circuit in
case some unusual unsafe voltage is detected. The ELCB otherwise are special
kind of latching relay which disconnect power from the system on sensing an
electrical shock.
What type of protection does the ELCB provide?
The ELCB trips and disconnect the electrical supply
within 0.1 Sec when someone gets an electrical shock and thus protects the
person, equipment, and electrical system from being getting a significant
electrical shock occurring later in the electrical system due to short circuit
or Overload. It detects the fault and disconnects the system while providing it
with a high impedance path to restrict the fault current within lower limits.
How are ELCBs rated?
They ELCBs are rated as MCBs from 0.5-63A with a
short circuit breaking capacity of 3-10 KA at 230V or 240V.They could be single
pole, double pole, triple pole & four poles with neutral poles if desired.
What are the Characteristics of ELCB?
The ELCBs generally come with these characteristics
–
The Phase,
neutral and main earth is to be connected to the ELCB.
It
operates on the amount of leakage current flowing in the system.
What is RCCB?
RCCB stands for Residual Current Circuit Breaker and
is essentially current sensing equipment to guard low voltage electrical
circuits which operates when it detects a fault in the system.
What type of protections RCCB provides?
Like ELCBs, the RCCBs also protect from the
electrical shocks with a single difference that they are current sensing devices
while ELCBs are voltage sensing and takes slightly higher time to activate
during the fault.
How are RCCBs rated?
They are rated similar to ELCBs
What are the Characteristics of RCCBs?
The RCCBs come with following characteristics –
In them,
only Phase and neutral are connected through it, unlike the main earth being
connected in ELCB.
It
operates in case of ground fault only to trip the circuit while disconnecting
the load from the electrical power supply.
It ensures
that the current passing through the Phase should be the same as passing
through the neutral. In case of any discrepancy it operates and trips the
circuit.
They are
more effective than the ELCBs and operate in a shorter time.
What is RCD?
RCD stands for Residual Current Device and keeps a
check on the current entering in an electronics device through Phase and the
current coming out of it through neutral. In case of deviation between two, the
RCB triggers the protection disconnecting the device from the electrical
supply.
How are RCDs rated?
They are rated similar to ELCBs and RCCBs.
What type of protections does RCDs provide?
RCDs provide earth fault protection and protection
against receiving an electrical shock.
What are the Characteristics of RCDs?
RCDs come with following characteristics –
They are
rated from 30mA to 10mA and typically operates within 30m Sec in case of a
fault.
Both Phase
and Neutral are connected to it unlikely earth as connected in ELCB
It
triggers during an earth fault and is effective for electric shock protection.
All
individual circuits should be guarded with RCD to let MCBs operates properly;
the otherwise adequate amount of current significant to trigger MCB will not be
generated, resulting in malfunctioning.
Conclusion – The MCB, MCCB,
ELCB, RCCB and RCD are all protective gadgets designed for protecting
electrical systems, circuit wiring, equipment, human life, and property from
various faults occurring in the electrical system and should be installed as
per the type of protection required besides selecting the correct rating of
these protection gadgets to disconnect the electrical supply from the
electrical system and provide requisite protection.
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