elcb project

7/29/2019 ELCB Project

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ABSTRACT

The earth leakage circuit breaker or commonly called the ELCB is located inside the

home electrical panel or distribution board. This component of the home electrical

installation is designed to detect any leakage of electrical current. This so-called leakage

current occurs when there are some defects in the performance of some part of the

installation, which can be caused by faulty components or by injuries to the insulation of the

wiring, cables, electrical appliances or other accessories such as the switches and socket

outlets. When the current leakage occurs, the ELCB then trips the electricity supply within a

fraction of a second of the leakage being detected, before the magnitude of the current

reaches a lethal level. Therefore any possibility of serious injuries due to electric shock to

persons who are in contact with the electrical installation at that particular moment is

minimized.



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Problem identification:

o In fault finding first check in the power supply section of the ELCB.

o After checking the power supply section check the inbuilt circuit of the ELCB.

o Then check the circuit all component.

o Then check the input connector of the ELCB.

o After all component testing then check the inbuilt coil of the circuit. The coil

can be failed due to the over voltage of the power supply.

Specification of ELCB:

o Number of Pole: 2 Pole & 4 Pole.

o Rated Voltage: 22V For 1 & 440V For 3.50Hz.

o Earth Leakage Sensitivity: 3ma to 30ma.

o Earth Leakage Tripping Time: Less than 0.03 Second

o Over Voltage Cut Off: 290V, 50Hz, 5% Respect to Neutral.

o Over Voltage Cut Off Time: Less Than 0.1 Second



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Industrial process:

What is ELCB

The earth leakage circuit breaker or commonly called the ELCB is located inside the

home electrical panel or distribution board. This component of the home electrical

installation is designed to detect any leakage of electrical current.

This so-called leakage current occurs when there are some defects in the

performance of some part of the installation, which can be caused by faulty components or

by injuries to the insulation of the wiring, cables, electrical appliances or other accessories

such as the switches and socket outlets.

When the current leakage occurs, the ELCB then trips the electricity supply within a

fraction of a second of the leakage being detected, before the magnitude of the current

reaches a lethal level.

Therefore any possibility of serious injuries due to electric shock to persons who are

in contact with the electrical installation at that particular moment is minimized. The use of

ELCB in house wiring is required by law and omitting it is a serious offence.



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Component from the left, with the letters CLIPSAL on it. The left-most component is the

Shown in below figure of a typical home electrical panel. The ELCB is the second main switch

(in black color), while all other components on the right of the ELCB are the outgoing circuit

reakers.

Fault in ELCB:

o Problem in magnet

o Problem in coil

o Connector fails

o Inbuilt spring fail

o Fault in MCB switch

o Fault in power supply

COUNTER MACHINE



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Earth leakage protection

It is for protecting power distribution system, earth leakage devices are only for

protecting people from electrocution. An overload circuit breaker is designed to interrupt a

circuit when the current exceeds a preset limit. In a thermal type breaker, a small over-

current (due to overloading) can be tolerated for a prolonged period before tripping,

although a large over-current (due to a short circuit) will trip fairly quickly.

A magnetic type breaker will trip very quickly once its threshold current has been

reached. As the current necessary for fatal electrocution is less than a couple of Amp. For

duration of less than a couple of seconds, an overload breaker offers virtually no protectionfrom electrocution. Earth leakage protection devices are designed to trip for fault currents

between 10 ~ 100 am and for interrupt times between 40 and 100 milliseconds after a fault

current is sensed.

Earth leakage devices are based on the principle that the amount of current entering a

device should be exactly the same as the amount of current leaving the device and that any

discrepancy is due to current flowing somewhere that it shouldn't, which is a bad thing. If an

electrical appliance such as a luminaries is working properly all electrons entering the

luminaries will flow in down the active wire, around through the filament of the lamp and

out again down the neutral wire.



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If there is a fault in the wiring which somehow allows the body of the appliance to

become connected to the active line, then when someone touches the appliance, by being

electrocuted they provide a path to earth for the current which is not via the neutral; this is

the situation for which an earth leakage protection device is employed. An overload circuit

breaker will not care that a small, albeit fatal, additional current is now flowing.

In a protection device an earth leakage current is sensed by comparing the active and

neutral currents flowing through a circuit, usually by the simple means of measuring the

current induced in a coil through which both of the wires have been passed. Under normal

conditions, as there are identical currents in both wires and the currents will be flowing in

opposite directions, there will be no current induced in the coil. The current induced in the

coil by a fault condition can be used to trigger an interruption to the circuit.

You may meet them as RCDs (Residual Current Devices), ELCBs (Earth Leakage Circuit-

Breakers), CBRs (Core Balance Relays) or GFIs (Ground Fault Interrupts) but whatever your

background and whichever TLA[1] (Three Letter Abbreviation) you use, earth leakage

devices are not only a crucial component in your electrical safety scheme, they are

frequently also required by regulation. Let's look at what they do, how they do it and how

we can use them to improve safety without causing too many unnecessary disruptions to

what we do.

How to avoid a major production catastrophe? To place each device in your electrical

system on its own rather costly earth leakage protected circuit ensuring that only the faulty

device will be disconnected. A more cost-effective alternative may be to place devices with

known leakage on to a circuit which has an earth leakage protection device with higher

activation threshold or one designed specifically to work with the ballasts of discharge light

sources.



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Some devices may actually be so reduced in operational effectiveness that they are better

installed on circuits not fitted with an earth leakage device. These variations are often only

possible in fixed installations and must always be done in consultation with an electrician or

electrical engineer who is fully cognizant with the safety and operational requirements of

the situation.

Earth leakage protection is an important part of the electrical safety scheme for any

system, although it may present some implementation difficulties where there are conflicts

between the safety ideal and the operational reality. It is vital for us to make certain that

the system that we are using is configured to meet the best possible.

ELCB stands for core balance Earth Leakage Circuit Breaker and this device will break the

electrical circuit as soon as it detects any significant leakage. Once you have installed the

ELCB into the wiring system of your aquarium, it will continually monitor the current in both

the active and neutral wires in search of leakage. When it detects a large enough current

loss, the whole circuit will be cut off instantly, thus preventing electrical accidents from

happening. Since different appliances have different natural current losses, the cut of level

for ELCB:s normally varies from 10 milliamps to 30 milliamps. 30 milliamps is considered a

good level for aquarium use.



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Without an ELCB, a normal household switchboard with standard circuit breakers will

normally not cut off the circuit when a low magnitude leakage to earth occurs. The problem

is of course that even a low magnitude leakage can cause serious injury to humans. When

you hock up your aquarium equipment to a 240 volts outlet, a current of no more than 50

milliamps can be fatal, and no more than 10 milliamps is needed to give the aquarists a

serious, agonizing electrical shock.

Installing an ELCB is rather expensive and it is naturally tempting to spend the money

on more appealing aquarium thingamajigs. Setting some money aside to safeguarding

yourself, your family, your pets, and that kind neighbor who volunteered to care for your

fish during your vacation, from electrical accidents is however the best course of action in

the long run. Even a fairly insignificant electrical accident is a really agonizing experience

that no one should have to go through.



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Portable ELCB:s are self-contained units that you simply plug into the standard socket

before you plug in your aquarium equipment. It is normally a bit more expensive than the

wall mounted ELCB, but you can on the other hand plug it in yourself without having to hire

an electrician. You can also bring it along when you move to a new address or move your

aquariums to a new room in your house.

Earth bypassing

It is not unusual for ELCB protected installation to have a second unintentional

connection to earth somewhere, one that does not pass through the ELCB sense coil. This can

occur via in contact with the ground,



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Both RCDs and ELCBs are prone to one hand ELCBs are on average older, and hence

tend to have less well developed filtering against nuisance trips, and on the other hand

ELCBs are inherently immune to some of the causes of false trips RCDs suffer, and are

generally less sensitive than RCDs. In practice RCD nuisance trips are much more common.

Another cause of nuisance tripping is due to accumulated or burden currents caused by

items with lowered insulation resistance. This may occur due to older equipment, or

equipment with heating elements, or even wiring in buildings in the tropics where prolonged

damp and rain conditions can cause the insulation resistance to lower due to moisture

tracking. If there is a 30 am protective device in use and there is a 10mA burden from various

sources then the unit will trip at 20 am. The individual items may each be electrically safe buta large number of small burden currents accumulates and reduces the tripping level. This was

more a problem in past installations where multiple circuits were protected by a single ELCB.

Heating elements of the tubular form are filled with a very fine powder that can absorb

moisture if the element has not be used for some time. In the tropics, this may occur, for

example if a clothes drier has not been used for a year or a large water boiler used for coffee

etc has been in storage. In such cases, if the unit is allowed to power up without RCD

protection then it will normally dry out and successfully pass inspection.



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The problem solution out line analysis:

o The fault in magnet, when remove the magnet & replace the new magnet. And new magnet

is place and this problem is solved.

o The fault in inbuilt coil, when remove this coil & replace the new coil.& this problem will be

solved

o The fault in connector will be failed when this coil is replacing the new coil when this

problem will be solved.

o The fault in inbuilt spring when new coil is replaced & then this fault is solved.

o The MCB switch is fail the new MCB switch is replace & this fault is solved

Advantages

o They are less sensitive to fault conditions, and therefore have fewer nuisance trips.

o This does not mean they always do, as practical performance depends on

installation details and the discrimination enhancing filtering in the ELCB.

o Therefore by electrically separating cable armor from cable CPC, an ELCB can be

arranged to protect against cable damage only, and not trip on faults in down line

installations.

Application

o It can use in industrial area.

o It is used in home implies.

o It is used in office.

o It is used in over voltage protection.



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What is the difference between MCB, MCCB, ELCB, and

RCCB

MCB (Miniature Circuit Breaker)

Characteristics

Rated current not more than 100 A.

Trip characteristics normally not adjustable.

Thermal or thermal-magnetic operation.

MCCB (Moulded Case Circuit Breaker)

Characteristics

Rated current up to 1000 A. Trip current may be adjustable.

http://electrical-engineering-portal.com/download-center/electrical-software/circuit-breaker-tripping-settings





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Thermal or thermal-magnetic operation.

Air Circuit Breaker

Characteristics

Rated current up to 10,000 A.

Trip characteristics often fully adjustable including configurable trip thresholds and

delays.

Usually electronically controlled — some models are microprocessor controlled.

Often used for main power distribution in large industrial plant, where the breakers

are arranged in draw-out enclosures for ease of maintenance.

Vacuum Circuit Breaker

Characteristics

With rated current up to 3000 A,

These breakers interrupt the arc in a vacuum bottle.

These can also be applied at up to 35,000 V. Vacuum circuit breakers tend to have

longer life expectancies between overhaul than do air circuit breakers.

RCD (Residual Current Device / RCCB(Residual Current

Circuit Breaker)

Characteristics

Phase (line) and Neutral both wires connected through RCD.

It trips the circuit when there is earth fault current.

The amount of current flows through the phase (line) should return through neutral .

It detects by RCD. any mismatch between two currents flowing through phase and

neutral detect by -RCD and trip the circuit within 30Miliseconed.

If a house has an earth system connected to an earth rod and not the main incoming

cable, then it must have all circuits protected by an RCD (because u mite not be able

to get enough fault current to trip a MCB)

RCDs are an extremely effective form of shock protection

http://electrical-engineering-portal.com/comparison-between-vacuum-and-sf6-circuit-breaker



http://electrical-engineering-portal.com/types-of-electrical-power-distribution-systems






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The most widely used are 30 mA (milliamp) and 100 mA devices. A current flow of 30 mA

(or 0.03 amps) is sufficiently small that it makes it very difficult to receive a dangerous

shock. Even 100 mA is a relatively small figure when compared to the current that may flow

in an earth fault without such protection (hundred of amps)

A 300/500 mA RCCB may be used where only fire protection is required. eg., on lightingcircuits, where the risk of electric shock is small.

Limitation of RCCB

Standard electromechanical RCCBs are designed to operate on normal supply waveforms and cannot be guaranteed to operate where none standard waveforms are

generated by loads. The most common is the half wave rectified waveform sometimes

called pulsating dc generated by speed control devices, semi conductors, computers

and even dimmers.

Specially modified RCCBs are available which will operate on normal ac and

pulsating dc.

RCDs don’t offer protection against current overloads: RCDs detect an imbalance

in the live and neutral currents. A current overload, however large, cannot be

detected. It is a frequent cause of problems with novices to replace an MCB in a fuse

box with an RCD. This may be done in an attempt to increase shock protection. If a

live-neutral fault occurs (a short circuit, or an overload), the RCD won’t trip, and may

be damaged. In practice, the main MCB for the premises will probably trip, or the

service fuse, so the situation is unlikely to lead to catastrophe; but it may be

inconvenient. It is now possible to get an MCB and and RCD in a single unit, called an RCBO (see

below). Replacing an MCB with an RCBO of the same rating is generally safe.

Nuisance tripping of RCCB: Sudden changes in electrical load can cause a small,

brief current flow to earth, especially in old appliances. RCDs are very sensitive and

operate very quickly; they may well trip when the motor of an old freezer switches

off. Some equipment is notoriously `leaky’, that is, generate a small, constant current

flow to earth. Some types of computer equipment, and large television sets, are widely

reported to cause problems.

RCD will not protect against a socket outlet being wired with its live and neutralterminals the wrong way round.

RCD will not protect against the overheating that results when conductors are not properly screwed into their terminals.

RCD will not protect against live-neutral shocks, because the current in the live

and neutral is balanced. So if you touch live and neutral conductors at the same time

(e.g., both terminals of a light fitting), you may still get a nasty shock.



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ELCB (Earth Leakage Circuit Breaker)

Characteristics

Phase (line), Neutral and Earth wire connected through ELCB.

ELCB is working based on Earth leakage current.

Operating Time of ELCB:

o The safest limit of Current which Human Body can withstand is 30ma sec.

o Suppose Human Body Resistance is 500Ω and Voltage to ground is 230 Volt.

o The Body current will be 500/230=460mA.

o Hence ELCB must be operated in 30maSec/460mA = 0.65msec

RCBO (Residual Circuit Breaker with OverLoad)

It is possible to get a combined MCB and RCCB in one device (Residual Current

Breaker with Overload RCBO), the principals are the same, but more styles of

disconnection are fitted into one package

Difference between ELCB and RCCB

ELCB is the old name and often refers to voltage operated devices that are no longer

available and it is advised you replace them if you find one.

RCCB or RCD is the new name that specifies current operated (hence the new name

to distinguish from voltage operated).

The new RCCB is best because it will detect any earth fault. The voltage type only

detects earth faults that flow back through the main earth wire so this is why they

stopped being used.

The easy way to tell an old voltage operated trip is to look for the main earth wireconnected through it.



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RCCB will only have the line and neutral connections.

ELCB is working based on Earth leakage current. But RCCB is not having sensing or

connectivity of Earth, because fundamentally Phase current is equal to the neutral

current in single phase. That’s why RCCB can trip when the both currents are

deferent and it withstand up to both the currents are same. Both the neutral and phase

currents are different that means current is flowing through the Earth. Finally both are working for same, but the thing is connectivity is difference.

RCD does not necessarily require an earth connection itself (it monitors only the live

and neutral).In addition it detects current flows to earth even in equipment without an

earth of its own.

This means that an RCD will continue to give shock protection in equipment that has

a faulty earth. It is these properties that have made the RCD more popular than its

rivals. For example, earth-leakage circuit breakers (ELCBs) were widely used about

ten years ago. These devices measured the voltage on the earth conductor; if this

voltage was not zero this indicated a current leakage to earth. The problem is that

ELCBs need a sound earth connection, as does the equipment it protects. As a result,

the use of ELCBs is no longer recommended.

MCB Selection

The first characteristic is the overload which is intended to prevent the accidental

overloading of the cable in a no fault situation. The speed of the MCB tripping will

vary with the degree of the overload. This is usually achieved by the use of a thermal

device in the MCB.

The second characteristic is the magnetic fault protection, which is intended to

operate when the fault reaches a predetermined level and to trip the MCB within one

tenth of a second. The level of this magnetic trip gives the MCB its type characteristicas follows:

Type Tripping Current Operating Time

Type B 3 To 5 time full load current 0.04 To 13 Sec

Type C 5 To 10 times full load current 0.04 To 5 Sec

Type D 10 To 20 times full load current 0.04 To 3 Sec

The third characteristic is the short circuit protection, which is intended to protect

against heavy faults maybe in thousands of amps caused by short circuit faults.

The capability of the MCB to operate under these conditions gives its short circuitrating in Kilo amps (KA). In general for consumer units a 6KA fault level is adequate

whereas for industrial boards 10KA fault capabilities or above may be required.

Fuse and MCB characteristics

Fuses and MCBs are rated in amps. The amp rating given on the fuse or MCB body is

the amount of current it will pass continuously. This is normally called the rated

current or nominal current.

Many people think that if the current exceeds the nominal current, the device will trip,

instantly. So if the rating is 30 amps, a current of 30.00001 amps will trip it, right?

This is not true.



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The fuse and the MCB, even though their nominal currents are similar, have very

different properties.

For example, For 32Amp MCB and 30 Amp Fuse, to be sure of tripping in 0.1

seconds, the MCB requires a current of 128 amps, while the fuse requires 300 amps.

The fuse clearly requires more current to blow it in that time, but notice how much

bigger both these currents are than the ’30 amps’ marked current rating. There is a small likelihood that in the course of, say, a month, a 30-amp fuse will trip

when carrying 30 amps. If the fuse has had a couple of overloads before (which may

not even have been noticed) this is much more likely. This explains why fuses can

sometimes ‘blow’ for no obvious reason

If the fuse is marked ’30 amps’, but it will actually stand 40 amps for over an hour,

how can we justify calling it a ’30 amp’ fuse? The answer is that the overload

characteristics of fuses are designed to match the properties of modern cables. For

example, a modern PVC-insulated cable will stand a 50% overload for an hour, so it

seems reasonable that the fuse should as well.

EARTH LEAKAGE CURRENTS AND ELCBs

Poor insulation in electric devices and equipments is the cause of earth leakage currents.Earth

leakage currents are a major source of two very common electrical hazards :

Risk of fire

Risk of electrocution

In addition to the above, continuous undetected earth leakage currents also result in waste

of electricity.

Protective devices like fuses/MCBs seldom offer protection against earth leakage

currents.More often the magnitude of these are much below the operating level of the fuse

or MCB thus rendering them ineffective.

The only effective protection against earth leakage currents is provided by Earth Leakage

Circuit Breakers(ELCBs) which are also known as Residual Current Circuit Breakers

(RCCBs).An MCB + ELCB combination provides complete protection against not just

shocks and electrocution,but also fires due to overloads,short-circuit and earth leakage.It also

saves valuable energy.



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EFFECT OF ELECTRIC CURRENT ON HUMAN BODY

The effect of electric current passing through a human body depends upon the current

strength,the time for which the current passes through the body as well as the organs involvedin the path of current.

Current Effect

1 ~ 10 mA Mild sensation

10 ~ 20 mA Human body remains stuck to the conductor

20 ~ 30 mA Muscle contraction

70 ~ 100 mA The heart begins to vibrate

500 mA Death – Cardiac Arrest / Nervous breakdown

Safe value of current in amperes(rms) which a human body can tolerate is given by :

I = 0.165/ sq. root of t for t < 3 secs

And I = 9 mA for t > 3 secs

Where ‘t’ is the time duration in seconds of the flow of current.

The current values generally considered as safe limit are :

30 mA for time < 1 sec.

300 mA for time < 50 ms.

500 mA for time < 30 ms.

The above facts and figures clearly bring out the importance of ELCBs.

Table 1: Human resistance to electrical current

Body Area Resistance (ohms)

Dry skin 100,000 to 600,000

Wet skin 1,000

Internal body (hand to foot) 400 to 600

Ear to ear ~100



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The approximate effects of electric current on the human body:

AC Current DC Current Effect

10 milliamps 1 milliamp Threshold of sensation

>60milliamps

>10milliamps

Strong involuntary muscle contractions.

You may not able to release a live wire. You may be thrown

across the room by the contraction!

>500

milliamps

100

milliamps

Cardiac Arrest!!!!

The amount of current through the human body for a given voltage depends on the resistance

of the body. The interior of the human body is a good conductor due to the abundance of ionsin the body fluids. The main barrier to current flow is the skin. The resistance of the skin

decreases significantly when it is wet.

A new rule 61A, introduced in July 1985 in the Indian Electricity Rules,makes the use of

Earth Leakage Protective Devices mandatory for all medium voltage installations and all low

voltage (240 V) installations above 5 KW.

FIVE GOOD REASONS FOR USING ELCBs

1. PROTECTION AGAINST INDIRECT CONTACT : Due to internal fault or

insulation failure metal enclosures of electric appliances can become live and cause

electric shock to unwary persons touching them.ELCB trips instantaneously and thus

exclude possible risk from dangerous indirect contact.

2. PROTECTION AGAINST DIRECT CONTACT : Accidental contact with live parts

of electric appliances cause earth leakage currents to flow through the human body

resulting in shock that may be fatal.ELCB trips immediately under these

circumstances and saves human life.

3. PROTECTION AGAINST ELECTRIC FIRES : Earth leakage current of 500 mA and

above cause electric sparks which can spread into major fires.Such leakages are

quickly detected by ELCBs which isolate the faulty circuit.



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4. ENERGY SAVINGS : Non-productive earth leakage current is measured by the

energymeter as part of the total energy consumption.The ELCB detects these leakages

and trips,helping us to rectify the fault and thus save energy.

5. PROTECTION OF EARTHING AGAINST CORROSION : Earth leakage currents of

higher magnitude cause corrosion through electrolysis.The ELCB ensures that the

earthing remains intact.

ELCBs are generally available in the sensitivity range of 30 mA/100 mA /300 mA.

ELCBs of 30 mA sensitivity offer adequate protection against even direct touch with medium

voltage and are meant for personal safety,whereas ELCBs of 300 mA sensitivity are suitable

for the prevention of fire hazards and are crucial for protection of property.

30 mA RCCB

The current passing through human body is likely to be between 80 ~ 240 mA in case of

direct contact at 230 V.The protective device should operate within 50 ms at 240 mA and 240

ms at 80 mA to be within zone-2 (safe) of the IEC curves.Both these conditions are fulfilled

by the 30 mA RCCB and therefore it provides a very high degree of protection against

electrocution.



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CONCLUSION :

Thus we see that the money invested in ELCBs in industry as well as our home goes a long

way in saving our lives and property.The electrical consultants and common users shall,therefore, adopt this wonderful device to safeguard against the hazard of electric shock and

fire.

Appendices

o ELCB: Earth leakage circuit breaker.

o RCD : Residential current devices.

o MCB: Miniature circuit breaker.

o CBR : Core Balance Relays

o GFI : Ground Fault Interrupts



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elcb project

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