• What Is The Difference Between Elcb And Rcbo
• Difference Between Elcb And Rccb

General catalogue. System pro M compact®. Technical guide. Protection against earth faults with Residual Current Devices. RCD block + MCB. Three-phase frequency converter. ABB asynchronous motor. Cooling system. (including single phase inverter). Electrical circuit breaker is a one kind of switching device which can be activated automatically as well as manually to control and protect an electrical power system respectively. As the current power system deals with vast currents, the special notice should be given throughout designing of circuit breaker to secure break of.

RCD (Residual Current Device / RCCB(Residual Current Circuit Breaker) Characteristics. 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 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 lighting circuits, 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 neutral terminals 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. 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:. The safest limit of Current which Human Body can withstand is 30ma sec.

Suppose Human Body Resistance is 500Ω and Voltage to ground is 230 Volt. The Body current will be 500/230=460mA. Hence ELCB must be operated in 30maSec/460mA = 0.65msec.

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 wire connected through it. 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 characteristic as 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 circuit rating 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. 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.

About Author Jignesh Parmar - Jignesh Parmar has completed M.Tech (Power System Control),B.E(Electrical). He is member of Institution of Engineers (MIE),India. Membership No:M-1473586.He has more than 13 years experience in Transmission -Distribution-Electrical Energy theft detection-Electrical Maintenance-Electrical Projects (Planning-Designing-Technical Review-coordination -Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. He has published numbers of Technical Articles in “Electrical Mirror”, “Electrical India”, “Lighting India”, “Industrial Electrix”(Australian Power Publications) Magazines.

He is Freelancer Programmer of Advance Excel and design useful Excel base Electrical Programs as per IS, NEC, IEC,IEEE codes. He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & Knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics. Dear Jigneshbhai, I stay at Mangalore and I am a layman as far as Electricity is concerned, earlier I was staying at Ahmedabad where the electricity was of good quality. Your article was very informative.Here in Mangalore many times I have noticed that after a power outage when the power returns, there is current in the neutral line. It may be due to faulty re-connection by the electricity linesman.

At this time if any appliance is on, it gets fried, also we get a shock on touching the appliance. Some of my appliances were destroyed because of this. I would like to know if I can use Residual circuit device(RCD) to prevent damage to appliances or will a 3 pin adapter with fuse will help.

Or is there any other device that can help prevent damage to appliances when there is current in Neutral( as tested with a screw driver tester). Power outage occurs here at least 3 times a day!! Thanks in advance. 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.

The RCCB will operate and cut off supply to the load if there is an unbalance (or difference) in the currents flowing thru the Phase (Line or Live) wire and the Neutral wire. In the Malaysian system, all equipment and utensils ( esp. Those made of metal), the body or casing is connected to an Earth wire, which originates from the Main Switch Board.

In the unlikely event of the Phase wire coming into contact with the body of the appliance (e.g. A bread toaster), a leakage current will flow from the body of the appliance to Earth, causing an unbalance in the RCCB and forcing it to trip and isolate the load. If an Earth wire system is not provided, the RCCB will trip only when a human touches the appliance, causing a current to flow thru him to Earth or Ground, resulting in an unbalance in the RCCB. An efficient RCCB needs to be sensitive to about 30mA leakage current and operate fast enough to avoid any hazard to the human. I believe this is not dangerous as when we use a Test Pen on the Phase wire, a small current does flow thru our body to Earth causing the lamp to light.

The doubt is whether the current thru our is the same in both instances. Thank you and hoping for some clarification on this matter. Thank u v.much Sir. I’ve few doubts. V r constructing a 2BHK house in Chennai.

Can i re-use a 4yr old (was working) 40A AUTO PHASE CHANGER? I also have 25A Rotary phase changers (say RPC) in a box, and in same DB box, 12 LeGrand MCBs (2x c20,4x c16, 2x c10, 4x c6) r there. Shall i connect 3 parts/places(AC1, AC2, & Kitchen) to these RPCs via 63A RCCB in DB & again take back to DB & connect with MCBs?!! So that i can connect confidently all remaining divisions with AUTO-PHASE CHANGER.

Also i’ll be glad if i get a chance to talk with you rgdg it. Am not comfortable in txting Thank u Sankar TL. Hi Jignesh I was following through ur various posts on meter bypass. I have a scenario on which I would like ur valuable expert comments.

I live in a multi storied government quarter. I would like to know how to bypass the single phase electronic meter. It is giving me sleepless nights. Presently both the live and the neutral from the meter goes to a MCCB which then terminates in our flats DP.One option I am considering is like using 2 wires from one live phase from main connection. One goes through the meter and other directly to the house.

Since distance from the meter to our house is considerable I cannot discreetly lay a new line to the flat I plan to disconnect the neutral in the MCCB and connect the unmetered live wire to the neutral port of the MCCB. In this way 2 wires both having the same phase would be coming to my flat from a single MCCB. We have 2 separate earth connections to the flat. For neutral I plan to use the earth wire.

The second earth will be used for the three pin connections so that they are secured. The metered live phase could be used for some very low load to ensure meter running for atleast the minimum units. The unmetered phase will be used for rest of the loads.

My query is- 1) Will the MCCB allow 2 live connections through it (both would of same phase so no 440 volts chance)? 2) Can I install a MCB with the earth which I would using as neutral. Dolph chebyshev array.

IF so, of how much rating. 3) What safety precautions should I take for preventing electrical shocks and equipment safety. Pse reply fast. With regards. @Meter Manager answers to your query: 1) don’t even try to do that. You can’t connect 2 feeder cables to one MCCB.

What Is The Difference Between Elcb And Rcbo

One of the resons is electric shock at the start point of cable although its feeding circuit breaker is disconnected. But, you can connect 2 cables from MCCB and supply 2 or more consumers. 2) you can’t do that neither. If there is a RCD it will trip in that case, and earth conducter must not carry current in normal regime, only in case of fault. 3) use appropriate protection (MCB, MCCB, RCD, RCBO, etc), cable sizing to match equipment needs, and use of appropriate IP rating for environment where equipment is installed.

March 20, 2011 MCB/MCCB/ ELCB /RCBO/ RCCB: MCB (Miniature Circuit Breaker). Rated current not more than 100 A. Trip characteristics normally not adjustable.

Thermal or thermal-magnetic operation. MCCB (Moulded Case Circuit Breaker):. Rated current up to 1000 A. Trip current may be adjustable. Thermal or thermal-magnetic operation.

Air Circuit Breaker:. 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:.

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 breakers tend to have longer life expectancies between overhaul than do air circuit breakers. RCD ( Residual Current Device ) / RCCB( Residual Current Circuit Breaker):. 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). 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 lighting circuits, where the risk of electric shock is small. RCDs are an extremely effective form of shock protection 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 neutral terminals 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. ELCB (Earth Leakage Circuit Breaker):. Phase (line), Neutral and Earth wire connected through ELCB. ELCB is working based on Earth leakage current. Operating Time of ELCB:. The safest limit of Current which Human Body can withstand is 30ma sec.

Suppose Human Body Resistance is 500Ω and Voltage to ground is 230 Volt. The Body current will be 500/230=460mA. 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).

Difference Between Elcb And Rccb

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 wire connected through it. 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 characteristic as 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 circuit rating 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. 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. Typical methods of provision of the main earthing terminal: Supply type code: TN-S.

Supplier provides a separate earth connection, usually direct from the distribution station and via the metal sheath of the supply cable. Supply type code: TN-C-S. Supplier provides a combined earth/neutral connection; your main earth terminal is connected to their neutral Supply type code: TT. Supplier provides no earth; you have an earth spike near your premises. About Jignesh.Parmar Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical) from Gujarat University.

He has more than 14 years experience in Power Transmission-Power Distribution-Electrical energy theft detection-Electrical Maintenance-Electrical Projects(Planning-Designing-coordination-Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. He is Freelancer Programmer of Advance Excel and design useful Excel Sheets of Electrical Engineering as per IS,NEC,IEC,IEEE codes. He is technical Author for 'Electrical Mirror' and 'Electrical India' Magazines. He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics.

Hi, I want to ask some basic thing that do we consider fault current for LV cable sizing? Fault current on LV bus remains approx. 50 kA for 1 sec., so if we are using outgoing MCB/MCCB and the fault current remains in the circuit for 100 ms. Then fault current will apprx. 16 kA so we have to go for min.

But we even use 2.5/4/6 sq.mm. Cable in LT circuit for lesser load demand.

MCB is available for 10 kA so it is also difficult to use MCB’s in this circuit, even MCB can’t be use in LDB’s for substation lighting as the fault current will not drop to 10 kA up to these LDB’s. Dear Sir, Greetings! Thank you for the informative article Some of the equipment terms are relatively new to me, though am aware of the MCB I have a couple of queries if you could kindly help me out with them that would be of great help 1. Where can I find these devices – ELCB and RCBO since some of the electric device dealers and electricians included were unaware of the same other than MCBs – Am from Bangalore any info of the Brand and dealer would be much appreciated 2. I have 3 Large MCBs installed at the Meters location for each of the Lines (3Phase) and indoors smaller MCBs that control the internal layout in terms of sections.

I had a 6ft Pit dug out and installed a GI Pipe with Copper plate at the bottom and screw and the required Copper wire and had them filled with Salt and Charcoal. Yet some time back had the MCB at borewell starter burn out without any of the MCBs tripping we identified the burnout by smell the electrician did change the MCB to a smaller capacity and the problem was resolved a few days back we had an issue with the TV and again the Technician blamed the fluctuation as the culprit. Jignesh parmarji, We are constructing housing quarters. The conducting is of concealed type. ALl our power,Telephone wiring,Inetnet wiring & Cable TV Wiring goes on the roof and comes down through the walls and ends at specified heights. Now our client wants that the Telephone,TV,Internet wiring to be below the floor (Below the tiles.).In this matter I want to know wheather it is permissible according to IndianTelegraphic Rules.Kindly guide me.

If you give me your mobile number it will be more helpful. Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical). He is member of Institution of Engineers (MIE),India. Membership No:M-1473586.He has more than 16 years experience in Transmission -Distribution-Electrical Energy theft detection-Electrical Maintenance-Electrical Projects (Planning-Designing-Technical Review-coordination -Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India.

He has published numbers of Technical Articles in “Electrical Mirror”, “Electrical India”, “Lighting India”,”Smart Energy”, “Industrial Electrix”(Australian Power Publications) Magazines. He is Freelancer Programmer of Advance Excel and design useful Excel base Electrical Programs as per IS, NEC, IEC,IEEE codes.

He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & Knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics.