What is MCB breaker: Full Form of MCB in Electrical, Working, Types, Applications

Hello, fellows, I hope all of you are enjoying your life. In today’s tutorial, we will have a look at the Full form of MCB in Electrical its construction, applications, and uses. The full form of MCB is Miniature Circuit Breaker, any type of circuit breaker is a switch that operates automatically in case of excessive current flow through the circuit due to overloading or short circuit. The operation of the breaker is similar to the fuse to break the circuit as some non-favorable conditions occur in the circuit like over current flow when fault removed it again restore the circuit normal condition.

There are numerous size and design of breakers are exits in the market according to circuit requirements. Small size circuit breakers used to provide protection such circuits where less value current is used and if any circuit breakers are assembled in a large array or board then this assembly called switchgear is used to protect large circuits. Switchgear are installed at the grid stations to protect incoming and outgoing feeders. There are numerous types of circuit breakers according to current ratings and applications. In today’s post, we will have a detailed look at a miniature circuit breaker and its related parameters. So let’s get started with the Full Form of MCB in Electrical.

Full Form of MCB in Electrical

• The word MCB stands for miniature circuit breaker like other circuit breakers this breaker also trip the circuit as large amount of current flows due to short circuit or overloading conditions.
•  In older small circuits that take less current used fuse to provide protection but nowadays fuse has been replaced with the miniature circuit breaker in these less current consuming circuits.

• The use of a miniature circuit breaker is more beneficial than the fuse as it restores current normal current flow as fault removed.
• But in case of fuse it the normal operation of the circuit takes time until the wire of fuse with the new wire.

Construction of MCB

• These are some parts of the miniature circuit breaker that used to design the MCB. Let’s discuss them with the detailed.

External Casing:

• The exterior casing of MCB is constructed with the any insulating material or plastic. It provides interior elements protection and assembles them at their respective places.

Contacts:

• There are numerous contacts are available in the form of pairs and one pair is immovable and others are not fixed.

Knob:

• The knob is used to on and off the circuit breaker operation.

Mechanical Latch:

• During on position force applied on the spring and compresses it in this condition to hold contacts in normal position, latching is used in the miniature circuit breaker.

Bimetallic strip:

• During overloading conditions, the current flowing is larger than the rated value of current then these bimetallic strips used to provide protection.

Solenoid:

• A solenoid is a coil used to provide protection in the short circuit occurrence by releases the mechanical latches.
• The solenoid operates only when the current flowing is three times the rated current of a breaker.
• Solenoid only operates in the case of the short circuit, not for overloading.

Arc Chutes:

• These chutes are used to quench the arc.

Operation of MCB

• There are main 4 functions performed by the miniature circuit breaker.

Switching

• The MCB can be on and off manually which makes it most effective during repairing the breaker.
• The exterior latching structure controls the immovable contacts as the knob press for the on of breaker.
• When the knob is pressed for on the breaker then the pressure given by the operator’s finger latch becomes free and opens the contacts of a breaker.

Overcurrent Protection

• Due to overloading a large amount of current flows through the breaker this current heated the bimetallic strip.
• Due to this heating shape of bimetallic strip changes that presses the latch and contacts of breaker gets off and current stops to flow.

Short Circuit Protection

• Due to the short circuit, an abrupt increment in current generates magnetomotive force so strong that it operates the latches and off the contacts of a breaker.

Arc Quenching

• Due to overloading conditions arc is created among the non-movable and movable contacts of breakers.

The design of contacts is such that they move the arc towards the arc quenchers or chutes that will remove the arc in the breaker.

Working Principle of MCB

• When the excessive current flows through the circuit due to overloading and short circuit the bimetallic strip of breaker gets heated and its shape changes.
• The shape variation of the bimetallic strip displaces the latching arrangements.
• The moveable contacts of the miniature circuit breaker are attached with the latching point any variation in the latching position also causes the movable contacts to open the circuit.

Types of MCB

• The types of circuit breakers are discussed here with the detailed.

Type B MCB

• The operating speed of miniature circuit breaker is 3 to 5 times of the value of rated current.
• The type of breaker is used in such circuits where resistive or inductive loads are used.
• Due to this, these are normally used in homes.

Types C MCB

• The operation speed of this breaker is 5 to 10 times the value of its current rating.
• These breakers are normally used in highly inductive loads such as motors.
• In these loads switching surges are large and these MCBs is the best option for these circuits.
• These breakers are so installed in industries for inductive loads like induction motors.

Type D MCB

• The operation speed of these breakers is 10 to 25 times the value of rated current.
• They are preferred for high inductive loads the use of these loads produces the large numbers of surges after a small-time interval of frequently.
• These breakers are used in X-ray machines, UPS, larger motors, etc.

Rating of MCB

• The current rating is the value of current over which breaker gets tripped. The rating of MCB is fixed and its operating range is between one ampere to one hundred amperes.

Difference Between MCB, MCCB, ELCB, RCCB

MCB

• Miniature circuit breaker provides protection to the circuit from the high value of current caused by the overloading, short circuit, and improper designing.
• It is the best replacement of fuse as after fault detection fust must be replaced but it removal of fault start operation again.
• So MCB is cost-effective while fuse used only for a single time.
• This breaker is also available in different types of poles arrangements such as one, two, three-pole and 4 poles with the neutral pole as well if required in any circuitry.

Features of MCB

• These are some features of the miniature circuit breakers.
• Its current rating is a hundred amperes.
• It operates thermally.
• Usually, its tripping is not controllable.

MCCB (Molded Case Circuit Breaker)

• A molded case circuit breaker is used to provide protection to any circuitry from the short circuit and overload current.
• It can use to handle the current of sixty-three amperes to three thousand amperes. This breaker can break the circuitry in case of fault manually and automatically.

• It also replaces the fuse as it can use again after removal of fault but the fuse can not be used again.
• As fuse to be purchased again but the breaker just reset for operation and it makes cost-effective over the fuse.

Features of MCCB

• These are some features of MCCB.
• Its current rating is up to one thousand amperes.
• Its tripping current can be adjusted while in MCB not adjusted.
• It operates thermally.

ELCB (Earth Leakage Circuit Breaker)

• To protect electrical circuits from the electric leakage the earth leakage circuit breaker is used as it can be guessed from its name.
• If someone intentionally touches the live wire and gets an electric shock, this breaker breaks the circuit in a time of 0.1 seconds and provide protection from serious damage.
• It used in grids station where high voltages are controlled and minor leakage current can be detected with the breaker and control electric shock due to current leakage.

Features of ELCB

• These are some features of ELCB described here with the detailed.
• For the interlinking of neutral, earth and phase wire ELCB is used.
• Current leakage in any circuitry defines the operation of ELCB.

RCCB

• The RCCB is stands for residual current circuit breaker used to provide protection to the circuit having less voltage flow.
• It has switch to break the circuit when a fault occurs. It also provides protection to the person from getting an electric shock.
• MOstly this circuit preferred for these circuits where a sudden electric fault occurs and electrical shock.
• To operation a practical understanding of the operation of this circuit, let’s assume that a person touches unintentionally a live wire he gets shock suddenly but if the circuit contains this breaker as he touches the wire breaker breaks the circuit suddenly.

Features of RCCB

• These are some features of RCCB.
• Neutral and phase wire also can be attached to the residual current circuit breaker.
• In the presence of a ground fault, it breaks the circuit.
• To protection from electrical shock, these breakers are mostly preferred.

So that is the detailed post about the full form of MCB in Electrical if you have any questions about MCB ask in comments. See you in another interesting post. Have a good day. Thanks, for reading.