The flow of current from the live conductor to the earth throughout an unintended lane is known as earth leakage. So it may supply in between their poor insulation (or) throughout a person’s body & cause electrical shock. The effect of this electrical shock causes damage to a device or a person if the leakage current goes beyond 30mA. So, protection devices like ELCB or earth leakage circuit breakers are used to separate the power source whenever current leakage is noticed. Earth leakage mainly occurs because of many reasons like broken conductors, live conductor’s damaged insulation, and whenever the live conductor approaches the equipment body, etc. This article provides brief information on ELCB or earth leakage circuit breaker, their working, and their applications.
What is an Earth Leakage Circuit Breaker?
Earth leakage circuit breaker definition is; a type of circuit breaker or safety device that is used to protect the circuit from leakage current and disconnect the power supply to the electric load whenever it detects the leakage current. These devices are mainly used for protecting the circuit or device against electrical shock.
The main function of ELCB is to avoid electrical shock and it checks the leakage current that supplies out from the circuit throughout any unintended path. They cannot defend against short circuit currents or overloading. So, these devices must be utilized in series with a miniature circuit breaker or MCB.
The ELCB working principle mainly depends on detecting leakage currents or ground faults and interrupting the power supply of the circuit rapidly to avoid harm. The flow of current from the source in normal conditions supplies into the load throughout the live wire & flows out from the load throughout the neutral wire but these two currents are equivalent in amount. If the flow of current leaks throughout any unintended path then an imbalance in between the live & neutral wire happens. The ELCB detects the imbalance with a current transformer & breaks the contacts with an electromagnetic relay.
An ELCB helps in protecting equipment and people from electrical shocks. These protection devices also detect & stop an electrical current that leaks to the ground. For electrical safety, ELCBs must be checked frequently to make sure they are correctly working or not.
The specifications of ELCB include the following.
- The rated voltage of this circuit breaker is typically 120V (or) 240V for higher voltages in industrial and residential applications.
- The rated current of this circuit breaker is from 5 to 50A @ 240VAC.
- The sensitivity of ELCB is typically 30 mA or below.
- The trip time of this circuit breaker typically ranges from 0.1 sec to 0.3 sec.
- This circuit breaker should be capable of withstanding repeated operations in fault conditions without losing its capability in tripping.
- The ELCB can detect both AC & pulsating DC leakage currents.
- The ELCB is mounted onto the electrical panel directly or onto a DIN rail.
- The ELCB must have a test button to allow the users to test the functionality of the device.
- This circuit breaker must meet relevant security & performance standards like; UL943, CE Mark & IEC 61008.
Earth Leakage Circuit Breaker Circuit Diagram
The earth leakage circuit breaker circuit diagram is shown below. This circuit includes a double pole switch which is connected to the supply & load sides. This switch is connected internally to a solenoid trip coil wherever this trip coil is connected between Earth & the exposed metal frame.
In the above circuit, the ‘E’ terminal of the trip coil is simply connected to the Earth electrode, and Terminal F is connected to the metallic enclosure. The double pole switch in normal operation is closed & the flow of current is from supply to load side throughout the two lines like Phase & Neutral. So in this period, there is no flow of current to earth between E & F terminals. Thus the voltage supply between the E & F terminal is almost Zero, so it is negligible.
In the fault condition case, the voltage on the ‘F’ terminal is connected simply to exposed metal work which rises up & the voltage supply at the E terminal is at zero potential. So there is an increase in potential variation between terminals E & F and causing the attached trip coil to function. After that, the trip coil movement opens up the double switch & therefore breaks the circuit.
The test button in the circuit is useful for testing the ELCB operation. Whenever this test button is pushed, then it connects the F terminal to the line through the test resistor temporarily. It detaches the supply reverse to the metal enclosure to keep away from hazardous electrical current supply back toward the metallic enclosure.
Earth Leakage Circuit Breaker Wiring Diagram
The earth leakage circuit breaker wiring diagram is shown below. In this wiring diagram, we use a single-phase energy meter, an SP MCB & an ELCB.
A single-phase energy meter is a type of watt-hour meter that includes two electromagnets. In single-pole miniature circuit breakers, switching & protection are simply affected only in a single Phase. This circuit breaker is normally used with 120V circuits & 6 to 20 amps MCB. These are designed with one Line Wire & one Neutral wire.
ELCB is an earth leakage circuit breaker that works simply on earth leakage production. Generally, this circuit breaker includes two cables; Phase & Neutral if any electric load is connected directly to the earth without using a neutral from the circuit breaker then this CB will trip automatically.
Initially, we need to provide an input power supply to the energy meter, and after that need to provide an input phase to the miniature circuit breaker from the energy meter. Afterward, we need to give a phase connection from MCB to ELCB & input a neutral connection to ELCB from the energy meter. After that, the input neutral & phase wire from ELCB to the load. Now it is ready to use.
Types of ELCB
There are two kinds of ELCB; voltage-operated and current which are discussed below. These types of circuit breakers simply detect the current leakage although their protection level & sensitivity provide are different.
Voltage Operated ELCB
A Voltage Operated ELCB is an electrical safety device, used to monitor imbalances of voltage within a circuit. This type of circuit breaker is used to trip the circuit whenever it notices leakage current and it protects the devices from electrical shocks and fire hazards caused by insulation breakdown or faulty wiring.
The advantages of voltage-operated ELCB mainly include; these are less expensive, less sensitive, they do not trip unnecessarily and they help in safety against electrical shocks. The disadvantages of voltage-operated ELCB include; that they cannot detect the leakage of current from phase to other earthed bodies. It avoids electrical shock when the phase conductor touches directly. It needs an additional connection through the body of the earth & equipment.
Current Operated ELCB
A current-operated ELCB is an electrical safety device that is used to monitor the flow of current throughout a circuit. This circuit breaker simply detects current leakage by simply contrasting the incoming & outgoing currents. This circuit breaker trips the electric circuit to avoid fire hazards & electrical shocks caused by ground faults or faults.
The advantages of current-operated ELCB include; that it is very reliable, more sensitive and it doesn’t need an earth connection. This circuit breaker breaks the circuit whenever the current leaks from any element of the circuit. It checks the residual current continuously & breaks immediately whenever it goes above its rated limit.
The disadvantages of the current operated ELCB include; these are expensive, it doesn’t have any overload protection, it doesn’t give protection from short circuit current and these are expensive.
Earth Leakage Circuit Breaker vs Residual Current Circuit Breaker
The difference between an earth leakage circuit breaker and a residual current circuit breaker includes the following.
Earth Leakage Circuit Breaker
Residual Current Circuit Breaker
|The term ELCB stands for “earth leakage circuit breaker.
|The term RCCB stands for “ residual current circuit breaker.
|ELCB device is directly connected to an earth cable thus it detects earth leakage current.
|RCCB device detects a fault current by simply measuring incoming & outgoing currents within the live & neutral wires.
|These safety devices are more efficient at direct leakage current detection to earth
|These devices are suitable for detecting various kinds of earth fault currents.
|It is a voltage-operated circuit breaker.
|It is a residual current-operated breaker.
|ELCB mainly depends on the voltage that is developed on its coil whenever there is a fault current supplied to Earth.
|RCCB works simply by comparing electric currents within its two line conductors.
|The ELCB has a single coil that is simply connected to the earth cable, the phase & neutral wires. Whenever there is a fault situation, this coil simply generates a voltage, thus helping the circuit breaker to detect the issue & trip the circuit.
|RCCB has two separate coils which help measure the flow of current within every conductor & a separate coil for operating the tripping mechanism.
|ELCBs are rated normally in tripping voltage, so they will trip at 50V.
|The RCCBs are rated typically in mA that ranges from 5 mA – 100 mA.
|MCCBs are expensive.
|RCCBs are less expensive.
|These circuit breakers are old devices, used in electrical installations for protecting the devices from electric shocks.
|These circuit breakers are new devices that are used nearly in all wiring systems for protecting from earth leakage currents.
What Does an Earth Leakage Circuit Breaker Do?
ELCB prevents electrical fires & electrical shock that are caused by a short circuit (or) overload within the control panel through an automatic shut-off whenever leakage is noticed.
What is the Difference between Circuit Breaker and Earth Leakage?
The main difference between a circuit breaker and earth leakage is; that the circuit breaker (CB) trips on overload (or) fault current whereas an earth current is a current that supplies within the earth conductor.
How Does an Earth Leakage Toroid Work?
The earth leakage toroids’ main job is to detect the fault current value continuously. If any fault is noticed, then it supplies a signal toward the residual current relay. Further, it switches its o/p connections to the shunt-trip for opening the circuit breaker.
What is Earth Leakage Current?
Earth leakage current is whenever the current supplying in a system discovers another return path other than neutral & active conductors. So, the term “earth leakage” is simply associated with a residual current of tiny magnitude & is usually measured in the order of mA (milli ampere).
Advantages and Disadvantages
The advantages of earth leakage circuit breakers include the following.
- This circuit breaker is not sensitive to electrical faults.
- It is very efficient and very efficient.
- These circuit breakers protect humans & animals from electrical shock.
- This circuit breaker is less sensitive.
- This circuit breaker doesn’t trip unnecessarily.
- These protection devices provide high protection against electrocution & electric shock by tripping the electric circuit very quickly in the event of an earth leakage.
- These circuit breakers protect equipment from any damages caused by electrical faults.
- ELCBs are fairly easy to install & can be retrofitted for existing electrical systems.
- These devices improve the security of an electrical system.
The disadvantages of earth leakage circuit breakers include the following.
- ELCBs cannot detect low leakage currents.
- These are less sensitive as compared to other types of circuit breakers like RCDs.
- They may not trip very quickly in the incident of a fault.
- It needs an extra connection.
- These protection devices need a sound earth connection mainly for load protection.
- These circuit breakers will fail to respond to certain conditions.
- These circuit breakers introduce extra resistance & additional points of breakdown into sufficient voltage to make it trip.
- It cannot detect any leakage from phase to any other earthed body.
- They do not notice any fault that doesn’t allow current throughout CPC to ground rod.
- ELCBs are mainly designed to be used in AC systems.
- These are not appropriate to use within DC systems.
- These circuit breakers provide security only against earth leakage & do not give safety against short circuits or over-currents.
- These devices may be tripped through the exterior voltage from something allied to the earthing system like a metal pipe, TN-S earth, TN-C-S combined neutral, etc..
- These protection devices can trip unnecessarily because of factors like high resistance within the earth connection (or) high resistance within the load.
- These devices do not permit a single building system to split easily into several sections through independent fault safety because the earthing system is connected to the pipe work.
The applications of earth leakage circuit breakers include the following.
- The ELCBs are used in many applications to avoid electrical fires & electrical shock that occur by an overload or short circuit within the control panel by an automatic shut off once leakage is noticed.
- This security device is used in electrical systems for detecting and avoiding the risks of electric shock & other hazards that occur by leakage of current to the earth.
- The ELCBs are used in commercial & residential buildings.
- These are used in construction sites, industrial applications, and medical and marine applications.
- ELCBs are very simple and effective security devices that can be utilized in different applications to defend equipment & people from the hazards of electrical current leakage.
Thus, this is an overview of ELCB or earth leakage circuit breakers. This is a safety device, used within electrical circuits including high Earth impedance to avoid the hazard of electrical shock. ELCB device is a voltage-operated device that detects little stray voltages across metal areas of electrical installations & also it interrupts the circuit if the level of voltage exceeds the hazard threshold. Therefore, the main function of ELCB is to notice Earth leakages & avoid harm to humans from electrical shocks. Here is a question for you, what is MCB?