What is MCCB?

MCCB, or Moulded case circuit breaker, are essential devices that block the high electricity in a wiring to prevent damage caused by overcurrent, short circuits, and other problems. 

Thus, they’re used for larger industrial and commercial uses. 

Continue reading to learn more about these devices, such as their working principle, ratings, and so on.

MCCB Defined

MCCB or Molded Case Circuit Breaker is what is used to protect electrical systems from overloads, short circuits, and other electrical anomalies. They are a type of circuit protection designed to handle higher currents which is why they’re often used in industrial and commercial settings.

Here are the key characteristics of MCCBs:

1. Overload protection: MCCBs’ main design is to trip and disconnect the circuit when the current exceeds a preset value. This feature prevents overheating of conductors and equipment. Thus, reducing the risk of electrical fires and equipment failure.
2. Adjustable trip setting: Several MCCBs come with adjustable settings. The feature accommodates various types of overcurrent conditions. This gives users the freedom to customize protection based on specific requirements.
3. Manual reset: After tripping, a MCCB requires manual resetting to restore the circuit. This ensures all issues are addressed before restoring the circuit.
4. Short circuit protection: In the event of a short circuit, MCCBs quickly interrupt the circuit to protect the electrical system. Failure to do so can cause an extremely high current surge.

Integrated design: The molded case design of MCCBs houses all internal components. This includes the tip mechanism and durable contacts, within a durable casing.

MCCB Working Principle and Definition

MCCBs (Moulded case circuit breakers) are devices that protect electrical systems from errors, including overloading. Therefore, they are capable of handling high electric currents and provide quick tripping when a fault arises in the system. It has numerous components that contribute to its working principle, which are: 

• Plunger
• Trip unit
• Solenoid
• Moulded case
• Arc extinguishing device
• Bimetallic strip and contacts

This device uses both thermal and magnetic trip systems. The trip mechanism is triggered when the amount of electricity flowing through the circuit surpasses its maximum rating for a long time. The bimetallic strip’s bends and moves the two contacts apart from each other, interrupting the flow. 

Meanwhile, the solenoid creates a magnetic field that pulls the plunger connected to the trip system when there’s a short circuit. Thus, the contacts will open instantly in response. Furthermore, the arc extinguishing device will ensure that it will reduce hazardous electrical sparks when the contacts separate.

Components of MCCBs

MCCBs have several key components that make them work the way they do: the trip mechanism, contacts, and thermal and magnetic elements. 

The trip mechanism is responsible for activating the circuit breaker when an abnormal current condition is detected. Contacts ensure efficient current interruption. They are typically made of high-quality materials like silver alloys. Thermal and magnetic elements work in tandem to detect overloads and short circuits.

Types of MCCB

Standard MCCBs

Standard MCCBs are the most common of all. They are designed for general-purpose applications and are widely used in commercial and industrial settings.

Electronic Trip MCCBs

Electronic trip MCCBs incorporate advanced electronic components for more precise and adjustable trip settings. They provide additional features such as adjustable trip curves and communication capabilities for more sophisticated protection and monitoring.

1. MCCB Type B: This class of MCCBs is designed to trip when they detect a current that is 3 to 5 times higher than their rated value. Type B MCCBs generally trip within 0.04 to 13 seconds, depending on the breaker’s rating.
2. MCCB Type C: The type C trips at faults between 5 to 10 times their rated value. MCCBs in this category can trip within 0.01 to 5 seconds. These MCCBs are suited for systems with motors and other inductive loads.
3. MCCB Type D: Tripping within 0.04 to 0.3 seconds, Type D MCCBs are designed to trip at higher fault currents, between 10 to 20 times their rated value.
4. MCCB Type K: These MCCBs trip when the current reaches 8 to 12 times the rated value. It takes 0.04 to 5 seconds for these MCCBs to trip. Type K MCCBs are well-suited for applications requiring protection against significant inrush currents.
5. MCCB Type Z: These MCCBs are highly sensitive. They will trip when they detect currents between 15 to 20 times their rated value.

Thermal Magnetic MCCBs

This type of MCCB combines both thermal and magnetic trip mechanisms. The thermal element responds to prolonged overcurrents, while the magnetic element reacts to sudden short circuits. 

Ground Fault MCCBs

Ground fault MCCBs or Ground Fault Circuit Interrupters (GFCI), are designed to protect against ground faults by quickly disconnecting the circuit when a ground fault is detected. They are commonly used in areas where electrical equipment might come into contact with water.

MCCB Features: What to Look For

When choosing MCCBs, these are some features to look for:

1. Current rating: Ensure that the MCCB is rated for the maximum current you expect it to handle.
2. Trip characteristics: Buy MCCBs that have adjustable trip settings. This is important if your application requires custom protection levels.
3. Breaking capacity: This feature refers to the maximum fault current the device can safely interrupt.
4. Auxiliary contacts: Some MCCBs come with auxiliary contacts for remote monitoring and control, adding convenience and flexibility.

Moulded Case Circuit Breaker’s Ratings

These devices have multiple ratings that determine their type and how much electrical current they can handle, which are some of the following:

Moulded Case Circuit Breaker Applications

Performance in Extreme Conditions

They are highly susceptible when exposed to severe conditions. According to Young-Maan Cho et al.’s studies, exposing them to higher temperatures, such as 45°C, can have a negative impact on their performance. This is because they’re prone to overheating due to the large electric currents they carry.

Furthermore, their materials insulation resistance can degrade under high humidity. This possibly leads to electric current flowing through unintended pathways, creating hazards such as electric shocks and fire. 

This explains why some manufacturers, like iALLWay, have MCCB requirements that state that when the ambient air temperature is +40°C, the relative humidity shall not exceed 50°C. 

Hence, they need regular checking and maintenance to maintain their excellent performance. Also consider looking for ones with a high IP rating or using anti-corrosion coatings and dehumidifiers in highly corrosive environments.

MCCB Circuit Breaker vs. Traditional Circuit Breaker

MCCB are capable of managing higher electric current flowing in the circuits, which ranges from 100 amps to 2500 amps. While a traditional circuit breaker can usually handle 800 amps only.

Thus, MCCBs are more preferable to larger commercial and industrial environments. On the other hand, traditional circuit breakers are appropriate for use in small commercial and residential settings. 

However, this increases the cost and space requirements of MCCB in comparison to traditional circuit breakers

Introducing iALLWay: Your Trusted Supplier of MCCBs

For high-quality Molded Case Circuit Breakers, iALLWay is a brand that you can rely on. The company offers a wide range of MCCBs that cater to different needs. These include commercial and industrial applications.

With their expertise and commitment to quality, iALLWay ensures that you have access to top-notch MCCBs that meet the highest standards of safety and performance.

An Indispensable Component of Electrical Systems

MCCBs are indispensable components of electrical systems. But if it’s quality MCCBs you’re looking for, look no further than iALLway MCCBs.

We offer a wide range of premium MCCBs you can rely on to protect your electrical system. Whether you’re looking for an MCCB with adjustable settings, current ratings, and high breaking capacity, iALLway has it.

Contact us today for a quote or visit our website for more information!

Resources:

DC Molded Case Circuit Breaker (MCCB) Applied for Solar Photovoltaic Systems

MCCB vs MCB: Understanding the Key Differences in Circuit Breakers

Analysis of Short-Circuit and Dielectric Recovery Characteristics of Molded Case Circuit Breaker according to External Environment

Insulation Resistance Testing and Humidity