What is MCCB? Functions, Components and Applications of MCCB.

16 Jun.,2025

 

What is MCCB? Functions, Components and Applications of MCCB.

In today’s world, the need for electricity is increasing. Not only do we realize the value of electricity during its scarcity but should also ensure smart ways to save electricity. To counter this issue, electricity control devices are being installed to monitor the flow of current.  Sometimes, overflow of current and short circuits can potentially damage the circuit. Low voltage switchgear is used to protect the circuits in the events of uncertainty. In this blog, we will uncover what is MCCB? and the functions, components and specifications of MCCB.

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What Is MCCB? 

MCCB is the acronym used for moulded case circuit breakers used to protect the electrical circuit and its components from excessive current. If this current is not isolated at the right time, it will lead to overload or a short circuit. These devices have a wide range of frequencies which makes them suitable for multiple applications to protect the electrical circuits. They are available in current ratings ranging from 15Amps to Amps making them usable in both low and high-powered applications. You can buy ABB MCCBs at the best prices by visiting our website www.micronovaimpex.com.

Functions of MCCB

● Protection against overload 

● Electric fault protection

● Switching the circuits on and off 

The MCCBs can be disconnected automatically and manually and are prominently used as a replacement for MCBs (miniature circuit breakers) in PV systems. MCCBs are housed within a moulded case to protect them from dust, rain, oil, and other chemicals. 

As these devices deal with the high current, it needs proper maintenance from time to time which can be done by regular cleaning, lubricating, and testing. 

Protect your electrical equipment 

All your electrical equipment needs a steady flow of current to function better. It’s important to install MCCB or MCB depending upon the load current. By doing so, the delicate machine control systems can be protected by isolating the power supply during electrical fault. 

Prevent Fires 

MCCBs that meet industry standards and are of good quality are suggested to ensure maximum safety. These electromagnetic devices detect fault at times of electrical surge or a short circuit to protect it from fire, heat, and explosion.

Components and Specifications of MCCB 

The four major components of MCCB include

  • Frame
  • Operating Mechanism
  • Arc Extinguisher
  • Trip Unit

Frame 

It is also known as the moulded case, provides space for insulated housing to mount all the circuit breaker components. This is made of a thermoset composite resin or a glass polyester to provide high dielectric strength within its compact design. The designation is assigned depending upon the type of the size of moulded case and is further used to describe the breaker’s characteristics (maximum voltage and current ratings). 

Operating mechanism 

Open and closing of the contacts is done through the operating mechanism. The speed of opening and closing the contacts is determined by how fast the handle is moved. If the contacts are tripped, you will be able to see the handle in a midway position. It’s impossible to trip the breaker if it’s in the on position, this is also called “trip-free”.

When the breaker trips i.e., if the handle is in the midway, it has to be moved to the off position first and then to the on position. In the case of breakers mounted in a group such as panel boards, the different handle positions are useful to find out the faulted circuit. Few breakers come with a manual trip to test the mechanism. 

Arc Extinguisher 

Arc Extinguisher: An arc is generated when a circuit breaker interrupts a current flow. The function of an arc extinguisher is to limit and divide that arc, thereby extinguishing it. The arc extinguishing chamber is enclosed in a high-strength insulation box which is mainly composed of a stack of steel plates. When the contacts split due to an interruption, the current flowing through the ionized area of the contacts generates a magnetic field around the arc and the arc extinguisher.

The lines of the magnetic field created around the arc drives the arc into the steel plates. The gas is then deionized, and the arc separates, allowing it to cool. Standard MCCB’s use a linear current flow through the contacts and under short-circuit conditions, a small blow-apart force is generated, which helps to open the contacts.

The majority of the opening action is developed by mechanical energy stored in the trip mechanism itself. This is because the current in both contacts flows in the same direction and attracts each other. Newer breakers use a reverse loop with current flowing in nearly opposite directions. This creates a repulsive action and results in a greater blow-apart force. This force assists rapid arc extinguishing by causing the contacts to open faster. The force is directly proportional to the size of the fault current. The greater the fault, the greater the force, and the faster the contacts open.

Trip Unit

The Trip Unit is the brain of the circuit breaker. The key function of a tripping unit is to trip the operating mechanism in the event of a short circuit or a sustained overload current. Conventional moulded case circuit breakers use electromechanical trip units. Protection of a circuit breaker is provided by combining a temperature-sensitive device with a current-sensitive electromagnetic device, both of which operate mechanically on the trip mechanism.

Electronic trip units are now available and they can significantly provide much more advanced protection and monitoring. Most moulded case circuit breakers utilize one or more different trip elements to provide circuit protection for various applications. These trip elements prevent thermal overloads, short circuits, and arcing ground faults.

Conventional MCCB’s provide either a fixed or interchangeable electromechanical trip unit. If a new trip rating is required for a fixed trip breaker, the entire breaker must be replaced. Interchangeable trip units are also known as rating plugs. Some breakers offer interchangeability between electromechanical and electronic trip units within the same frame.

To ensure the efficiency of MCCB in its operation, regular maintenance including visual inspection, cleaning, and testing should be done. 

Applications of MCCB 

MCCBs are designed to handle high currents and are used widely in heavy-duty applications such as adjustable trip settings for applications with low currents, protecting motors, protecting capacitor banks, welding machines, protecting generators and electric feeders.

Specifications of MCCBs

  • Ue – Rated Operational Voltage.
  • Ui – Rated Insulation Voltage.
  • Uimp – Impulse withstand voltage.
  • In – Nominal Rated Current.
  • Ics – Service Short Circuit Breaking Capacity.
  • Icu – Ultimate Short Circuit Breaking Capacity.

Differences between MCB and MCCB 

How Micronova provides you the best solution for MCCB?

We supply 1Pole, 2Pole, 3Pole and 4Pole MCCBs at the best prices and discounts online. 

Micronvoa’s technical expert team assists in selecting the best products or alternatives to match the customer requirements. We also 

  • Educate customers about the in-built functions of the products 
  • Help customers to buy the product at a competitive price
  • Help customers with VC installation
  • Provide on-time delivery 
  • Supply genuine products

Ranges of MCCB offered by Micronova 

ABB MCCBs are known for their quality and reliability. We are the leading online suppliers and distributors for ABB MCCBs.

The company is the world’s best mccb supplier supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

Molded Case Circuit Breaker or MCCB | How They Work

What are Molded Case Circuit Breakers?

Molded case circuit breakers, also known as MCBs, are a type of electrical protection device that is used to automatically turn off electric circuits when excess current flows through them.

MCCB Design and Components

MCBs consist of both mechanical and electrical components (thermal and magnetic) encased in a molded insulating material such as plastic or porcelain. This molded case gives them their name and provides protection against electric shocks and environmental contaminants.

The main components inside an MCB are:

  • A current carrying conductor
  • A tripping mechanism
  • An arc extinguishing chamber
  • Auxiliary contacts and alarm switches

When excess electricity flows through the breaker, a mechanism automatically triggers the contacts to open or "break" the circuit. This prevents damage from overloads and shorts. An arc chute inside extinguishes the arc produced from breaking the electrical circuit.

Advantages of MCCBs

Molded case circuit breakers provide several key advantages:

  • Compact size - MCBs are smaller than other breaker types.
  • Fast reaction - They can trip quickly, in as fast as a few milliseconds.
  • Adjustable - Some MCBs allow users to set desired trip current levels.
  • Easy to reset - Simply flipping the switch restores power.
  • Protection - Prevent fires and damage by interrupting overloads.
  • Affordable - MCBs are an economical type of circuit protection.

These benefits make molded case breakers a popular choice for residential, commercial, and industrial electrical systems.

MCCB Applications

Common applications for molded case breakers include:

  • Power distribution boards
  • Motor control centers
  • Industrial machine tools and robotic cells
  • HVAC equipment
  • Appliances
  • Commercial lighting fixtures
  • Generators

They provide reliable overload and circuit protection for both power and lighting branch circuits ranging from 15 to 125 amps. Different frame sizes are available for any installation environment.

MCCB Specifications and Rating

Molded case circuit breakers have published specifications that users reference to select the properly rated unit:

  • Voltage rating - Compatible voltage such as 240V or 480V.
  • Interrupting rating - Maximum short circuit current handled.
  • Trip curve type - Response time characteristics.
  • Number of poles - Single or multi-pole configurations.
  • Amp frame size - Designed mechanism for protection and isolation.

Additional considerations are altitude, temperature extremes, and any applicable compliance standards. Always consult technical datasheets when choosing MCBs.

Common MCCB Industry Brands Eaton and More

  • Eaton CH Series
  • Schneider NSX
  • GE Spectra Series
  • Siemens WL Circuit Breakers

These major manufacturers provide reliable, certified products tested to global standards within the industry. 

MCCB Protection Features

Many modern molded case breakers now integrate supplemental features used to protect the electrical circuit:

  • Ground fault - Detect dangerous leakage electricity.
  • Arc fault detection - Recognize hazardous arcing signatures.
  • Zone selective interlocking - Cascade tripping sequence.

This expands safety and coordination while minimizing downtime. Communicating circuit breakers are also emerging with network connectivity.

How to Select an MCCB

Follow these key steps when specifying and purchasing molded case circuit breakers for reliability:

  1. Determine correct frame size by checking equipment nameplates for full load amps or MCA.
  2. Choose suitable voltage, poles, and interrupt rating.
  3. Define necessary response time and fault curve characteristics.
  4. Consider any needed supplemental protection features.
  5. Reference manufacturer breaker catalogs and published datasheets.
  6. Ensure regulatory and standards compliance.
  7. Order from reputable suppliers to avoid counterfeit products.

This process helps identify the optimal molded case breaker for the application.

MCCB Testing and Maintenance

Routine molded case circuit breaker care involves:

  • Testing function per manufacturer guidance.
  • Cleaning debris and dust buildup.
  • Checking wiring terminations are secure.
  • Verifying tightness of any bolted connections.
  • Monitoring contact wear with resistance tests.
  • Recording exercise data to identify aging breakers.

Periodic inspection and testing ensures trouble-free MCB protection.

Frequently Asked Questions

Here are answers to common questions about molded case circuit breakers:

How do MCBs detect overloads?

Bimetallic strips or electronic solenoids sense excess temperature rise from overload currents. This activates the overload or short circuit mechanism.

What is the difference between MCBs and MCCBs?

MCBs are used for smaller branch circuits, while MCCBs (molded case circuit breakers) handle higher electricity associated with distribution circuits.

Why choose MCBs over fuses?

MCCBs can also be easily reset, while fuses require replacement. This provides convenience while avoiding downtime.

What causes nuisance tripping of MCBs?

Loose connections, oversized breaker ratings, frequent surges, and load harmonics can cause unwanted MCB faulting.

Are MCBs reusable after interruption?

Yes, the range of molded case breakers available are designed for repeated interruption and resetting throughout their product lifetime.

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