Electrical Knowledge

What is the difference between MCB and MCCB?

Publish Time: 2023-05-19 14:56:21     Author: DELIXI

MCB (Miniature Circuit Breaker) is an operational electronic device that prevents electrical circuits from overheating or causing a fire. Electrical problems resulting from overcharging or a short circuit are called short circuits. 

MCCB (Molded Case Circuit Breaker). It is implemented as another form of electrical equipment when the total voltage exceeds the limit of the miniature circuit breaker. Here's how it works: one for overheating and one for overpressure. It has a bimetallic copper-nickel contact that expands and contracts when the temperature changes outside the normal range. Under typical operating conditions, the contacts allow current to flow through the circuit. However, if the current exceeds a preset limit, the connection will heat up and stretch until it breaks. As a result, circuits are isolated from the power system, preventing damage to equipment and infrastructure.

MCB and MCCB. Both are commonly used low-voltage circuit breakers. They both play an important role in circuit protection and electrical safety. Although their functions are similar, there are some differences in construction design, Current rating, application and lifespan test.

Current rating: MCB is mainly used for short-circuit and overload protection of low current (usually below 100 amps, up to 18000 amps), while MCCB is mainly used for high current, used to disconnect larger circuits in industrial applications (usually in Above 100 amps, current range up to 200000 amps) short circuit and overload protection. This is due to the different structural designs and materials of MCB and MCCB to accommodate different currents and loads. MCCBs are designed for higher current ratings, ranging from several tens of amperes to thousands of amperes. They are used in industrial and commercial applications where larger electrical loads are present.

Construction: MCBs are compact and typically have a modular design, making them easy to install in distribution boards. They are generally rated for lower short-circuit breaking capacities. MCCBs, on the other hand, have a larger size and are often mounted on a DIN rail or bolted to switchgear panels. They are designed for higher short-circuit breaking capacities and can handle larger electrical systems.

Lifespan: MCBs usually use electronic components such as magnetic reeds and thermal relays for protection, while MCCBs use mechanical devices such as thermal magnetic protectors for protection. This is why they differ in mechanical life tests. When conducting mechanical life tests, both MCB and MCCB need to test their opening and closing times, contact resistance and protection functions and other parameters. The difference is that due to the small working current and rated current of MCB, their tests should be carried out under lower current and load, usually below 100A. However, the working current and rated current of MCCB are relatively large, and their tests should be carried out under relatively high current and load, usually above 100A.

When selecting and applying circuit breakers, MCB or MCCB should be selected according to specific circuit and load requirements, and corresponding mechanical life tests should be carried out to ensure its performance and reliability.

Adjustability: MCBs usually have fixed trip settings and are not adjustable by the end-user. MCCBs often provide adjustable trip settings, allowing users to customize the current levels at which the circuit breaker will trip. This adjustability provides flexibility to match specific requirements.

Applications: MCBs are commonly used in residential, small commercial, and light industrial applications. They are suitable for protecting circuits with lower current loads, such as lighting, small appliances, and domestic wiring. MCCBs are used in industrial plants, commercial buildings, data centers, and other applications where higher current levels and enhanced protection are required. They are capable of handling larger-scale electrical systems and protecting heavier loads.

Trip Characteristics: MCBs are available with different trip characteristics to suit specific applications. These characteristics determine the response time of the MCB to an overcurrent situation. The most common trip characteristics are B (for general purpose), C (for motor loads or applications with moderate inrush currents), and D (for applications with high inrush currents, such as transformers).

Resettable: Unlike fuses, which need to be replaced after tripping, MCBs are resettable. Once the fault is rectified or the overload condition is resolved, the MCB can be manually reset to restore power to the circuit.

Modular Design: MCBs are designed to be modular, allowing for easy installation in electrical distribution boards or consumer units. They are typically DIN-rail mounted and can be easily inserted, removed, or rearranged within the panel.

MCBs are an essential component of electrical safety systems as they protect against electrical faults that can lead to equipment damage, electrical fires, or electric shocks. They provide reliable and convenient circuit protection and are widely used in electrical installations worldwide.

We are a distributor of China DELIXI. Major in Power Distribution and Electrical Components. As a leading company in China's electrical industry, Delixi has five production bases, electrical products in China with more than 40,000 sales outlets, product and service support network covering more than 60 countries and regions. While gathering the main business of intelligent electric power, Delixi also actively deployed strategic emerging industries such as environment protection, exchange of things, millitar, and strived to promote the harmonious coexistence of economic growth, eco-friedliness, good life and national construction.


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