Difference Between MCB, MCCB, ELCB and RCCB

The most dependable and prominent power source for humankind for many years was electricity. At the time of this period, the demand for the usage and applications of electricity was extremely enhanced and developed as GDP all across various nations. With the enhancement of demand for power, many nations took it as a challenge and provided good infrastructure and extensive production. Behind the technicality of this, man has to be aware of the situations like power overloading and this led to the rise of electrical breaker which was generally termed as a circuit breaker. Today, the concept is all about these circuit breakers and knowing the difference between MCB and MCCB.

What is Circuit Breaker?

An electrical circuit breaker is 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 the designing of the circuit breaker to secure a break of the arc produced during the process of the circuit breaker. This was the fundamental definition of circuit breakers. These have been divided into various types based on special categories they have been subdivided into they are MCB and MCCB, ELCB & RCCB.

Difference Between MCB and MCCB, ELCB, and RCCB

Let us start with knowing each type of circuit breaker and then move ahead to know the difference between MCB and MCCB and their comparisons.

MCB – Miniature Circuit Breaker

A miniature circuit breaker is shortly named MCB which is the electromagnetic instrument that represents the entire compound in a molded insulating type of material. The crucial function of MCB is circuit switching which means that to make a circuit in an open condition.

This clearly means than when a circuit is connected to an MCB and when there happens the condition of excess current flow through MCB rather than the specified value, then it opens the connected circuit. Even this might be manually made to ON and OFF the switch if required just like a general switch.

It is also defined as the electromechanical device that guards an electrical circuit against an overcurrent, that may affect by a short circuit, overload, or imperfect design. This is a better option to a Fuse since it doesn’t require alternate once an overload is identified. An MCB can be simply rearranged and thus gives better operational protection and greater handiness without incurring huge operating costs. The operating principle of MCB is simple.

This kind of circuit breakers comes under the classification of delay tripping machines where the overcurrent level magnitude regulates the functional time. This clearly means that these devices will function when the overload takes place for a long period to generate complications for the circuit which is being safeguarded. So, miniature circuit breakers provide a response for the transient loads like motor initiation current supplies and switch rises. Usually, MCB’s are constructed to function minimally than 25 msec at the time of short circuits and 2 sec – 2 min while overloading conditions.

An MCB function by interrupting the stability of electrical flow through the circuit once an error is detected. In simple conditions, this circuit breaker is a switch which routinely turns off when the current flows through it and passes the maximum acceptable limit. Generally, these are designed to guard against over current and overheating.

MCB is substituting the rewirable switch-fuse units for low power domestic and industrial applications in a very quick manner. In the wiring system, the MCB is a blend of all three functions such as protection of short circuit, overload, and switching. Protection of overload by using a bimetallic strip & short circuit protection by a used solenoid.

These are obtainable in different pole versions like single, double, triple pole & four poles with neutral poles if necessary. The normal current rating ranges from 0.5-63 A with an asymmetrical short circuit breaking capacity of 3-10 KA, at a voltage level of 230 or 440V.

MCB Rating

The ampere rating states that the maximum value of current where the MCB  withstands without moving to trip condition. In the general MCB circuits, the current rating ranges from 2 Amp to 125 Amp. Whereas in the commercial applications, single-pole type of breaker circuits safeguard 20V branched circuits and double pole breaker circuits safeguard up to 240V branched circuits. Whereas the voltage rating in this miniature breaking circuit might be more than that of the circuit voltage but it will not be less than the circuit voltage.

The other type of MCB rating is faulted current disconnection rating which is also called a disconnection rating at the time of the short circuit. This is stated as the maximum offered fault current value which might be anticipated either from the overhead or pad installed distribution transformer external to the location.

For instance, when the transformer has the ability to generate 10,000 amps of current, then every breaker circuit that exists in the load center has to be rated for a minimum of 10,000 amps.

The MCB circuit diagram and the detailed working principle can be explained as below:

The functionality of this circuit breaker comprises two phases one in short circuit and the other is thermal functionality. The first one is dependent on the thermal impact of the overrated current whereas the second phase is dependent on the electromagnetic impact of the overrated current.

As there exist various kinds of miniature circuit breakers, every type functions on the air-break theory. It means the arc that exists in between the contacts is forcibly pushed into the splitter plates via arc runners. This triggers the arc to get divided into multiple series of arcs and then snuffs the arc by the extraction of energy from the arc and then by cooling it. Using a bimetallic strip, thermal functionality can be attained in the overload scenarios. When there is the flow of overloaded current from this breaker circuit, then the bimetallic strip will be warmed up and then this causes deflection.

In this process, it shows a movement in the trip lever and then opens up the latch process where the contacts get opened under the spring method.

And in the short circuit cases, the extended amount of fault current boosts up the solenoid and then the solenoid’s magnetic field attracts the plunger. This causes a change in the trip lever and so this shows a quick release of the latch process. At the time of contact separation, there will be the generation of arc both in the short circuit and overloaded cases. Then the developed arc will be moved towards the arc-cute stack under the magnetic fields’ impact. Thus because a single arc will get splitter into many arc chutes, but they will not exist for a longer period as because of their voltage drop

Characteristics of MCB

The characteristics of an MCB mainly include the following

• Rated current is not more than 100 amperes
• Normally, trip characteristics are not adjustable
• Thermal/thermal-magnetic operation

MCCB – Molded Case Circuit Breaker

The MCCB is used to control electric energy in distribution n/k and is having short circuit and overload protection. This Circuit Breaker is an electromechanical device which guards a circuit from short circuit and over current. They offer short circuit and over current protection for circuits ranges from 63 Amps-3000 Amps. The primary function of MCCB is to give a means to manually open a circuit, automatically open a circuit under short circuit or overload conditions. In an electrical circuit, the overcurrent may result in a faulty design

The MCCB is an option to a fuse since it doesn’t need an alternate once an overload is noticed. Unlike a fuse, this circuit breaker can be simply reset after a mistake and offers enhanced operator safety and ease without acquiring operating costs. Generally, these circuits have thermal current for over current and the magnetic element for short circuit release to work faster.

Overload safety is even offered by a molded case circuit breaker through a temperature-sensitive device. This device is mainly a bimetallic connection where the connection is that includes two metals that get enlarged at distinct rates when those are subjected high range of temperature values. In the general functional conditions, the bimetallic connection will permit the flow of electric current via MCCB. Whereas when the current value reaches more than the tripping voltage, then the connection will initiate to get heated up and then get molded because of the various thermal rating of heat enlargement inside the connection. And finally, the connection will bend over to the point of manually that pushes the tripping bar and unlocking the connection. This leads to circuit interruption.

The thermal safety of the molded case circuit breaker will usually have a time delay period where this permits a minimal period of overcurrent that is generally observed in few device functionalities, like that of inrush currents which can be observed in the initiation of motors. This time delay permits the circuit to remain to function in these conditions without tripping the device.

People who are constructing molded case circuit breakers need to specify the functional parameters. Few of those are

• Rated Current – This is the value that measures that when the breaker circuit trips because of overload security. This is a varied value where it can be modified up to the rated frame current value. It is represented in In.
• Rated Frame Current – This is the maximum amount of current that MCCB is rated to manage. It also specifies the maximum varied value of the trip current and also specifies the circuit frame size. It is represented in Inm.
• Rated Working Voltage – This is the rated amount of voltage when the circuit functions continuously. This is almost equal or near to the value of system voltage. It is represented as Ue.
• Rated Insulation Voltage – This is the value that specifies the uppermost voltage when the molded case circuit breaker can withstand in lab circumstances. In general, the rated voltage is less than that of the rated insulation voltage. This is represented as Ui.
• Functional Breaking Capacity – This is measured in short circuit conditions. A maximum fault current where the device can manage without causing permanent destruction for the device. These are normally reusable even after fault disruption functionality offered that they will not surpass this value. The increased value of Ics, the greater reliability for the circuit breaker.
• Impulse Withstand Voltage – This is the maximum voltage value where the circuit breaker can tolerate even in lightning strikes and switching rises. This value measures the device capability to maintain peak voltages. In general, the size for impulse testing is of 1.2/50 microseconds.
• Ultimate Breaking Capacity – This is the maximum value of fault current where MCCB can tolerate. The higher this value, the device will not be able to trip. Then, an additional security approach having maximum breaking capacity needs to function which means the functional reliability of MCCB. This is represented as Icu. The other crucial thing to be noted here is when the fault current is more than Ics but not Icu, then this states that the device can hold the ability to remove the fault. But in some cases, it might get damaged too.
• Electrical Life – This specifies the highest number of times that the device gets tripped before failing.
• Mechanical Life – This specifies the highest number of times that the device gets functioned before failing.

Characteristics of MCCB

The characteristics of an MCCB mainly include the following

• The range of rated current us up to 1000 amperes
• Trip current may be adjusted
• Thermal/thermal-magnetic operation

With the above-mentioned current ratings and comparisons, the difference between MCB and MCCB can be known clearly and this helps for the correct selection of the device as per an individual’s requirement.

ELCB – Earth Leakage Circuit Breaker

The ELCB is used to protect the circuit from the electrical leakage. When someone gets an electric shock, then this circuit breaker cuts off the power at the time of 0.1 secs for protecting the personal safety and avoiding the gear from the circuit against short circuit and overload.

ELCB is a security device used in electrical systems with high Earth impedance to avoid shock. It notices small stray voltages on the metal fields of electrical gear, and interrupt the circuit if an unsafe voltage is detected. The main principle of Earth leakage protectors is to stop injury to humans and nature due to electric shock.

This circuit breaker is a specialized kind of latching relay that has structures incoming mains power connected through its switching contacts so that this circuit breaker disconnects the power supply in an unsafe condition.

The ELCB notices fault currents from the life to the ground wire inside the installation it guards. If enough voltage emerges across the sense coil in the circuit breaker, it will turn off the supply, and stay off until reset by hand. A voltage-sensing earth leakage circuit breaker doesn’t detect fault currents from existing to any other ground body.

Characteristics of ELCB

The characteristics of an ELCB mainly include the following

• This circuit breaker connects the phase, earth wire, and neutral
• The working of this circuit breaker depends on current leakage

RCCB (Residual Current Circuit Breaker)

An RCCB is essential current sensing equipment used to guard a low voltage circuit against the fault. It comprises a switch device used to turn off the circuit when a fault occurs in the circuit. RCCB is aimed at guarding a person against the electrical shocks. Fires and electrocution are caused due to the wrong wiring or any earth faults. This type of circuit breaker is used in situations where there is a sudden shock or fault happening in the circuit.

For instance, a person suddenly enters in contact with an open live wire in an electrical circuit. In that situation, in the absence of this circuit breaker, a ground fault may occur and an individual is at the hazardous situation of receiving a shock. But, if a similar circuit is defended with the circuit breaker, it will tour the circuit in a second, therefore, avoiding a person from the electric shock. Therefore, this circuit breaker is good to install in an electrical circuit.

Characteristics of RCCB

The characteristics of an RCCB mainly include the following

• Both wires phase and neutral are connected through RCCB
• Whenever there is any ground fault occurs, then it trips the circuit
• The number of current supplies through the line should go back through neutral
• These are a very effective type of shock protection

Difference Between MCB and MCCB

The below tabular column clearly shows the key difference between MCB and MCCB circuits.

Difference Between RCCB and ELCB

The question that can be raised was also discussed in this article and it is why we use MCCB instead of MCB?

When we observe the difference between MCB and MCCB, both these devices are assessed in their power abilities, MCB is mainly employed for minimal current necessities like home wiring connections and minimal electronic circuits. But MCCB is the most recommended circuit breaker for high power applications. MCCB is a kind of electrical switch that safeguards the device from either short-circuiting or overloaded conditions.

And also, in MCB the interrupt rating is only 1800 amperes whereas MCCB interrupts rating values range from 10k – 200k amperes. To go with detailed current ratings and all, various organizations provide current rating charts based on their development.

So, this is all about what is a circuit breaker, the difference between MCB and MCCB. It also describes ELCB, RCCB, and their characteristics along with differences. Furthermore, any queries regarding this concept or to implement electrical projects, please give your suggestions, ideas, and feedback by commenting in the comment section below. Here is a question for you, what type of miniature circuit breaker is employed for alternating currents?

 Photo Credits:

• Miniature Circuit Breaker parkerhydraulics
• Earth Leakage Circuit Breaker diytrade
• Residual Current Circuit Breaker maharashtradirectory