In low-voltage power distribution systems, Mccb Circuit Breakers are essential electrical protection devices widely used in industrial, commercial, and civil power distribution projects. As a core component of Mccb Electrical systems, MCCBs fill the performance gap between miniature circuit breakers (MCB) and air circuit breakers (ACB), serving high-current equipment and circuits with reliable overload, short circuit, and undervoltage protection.
What Are MCCBs? MCCB is known as Moulded Case Circuit Breaker. The MCCB is used in places where adjustable tripping is required. It is essentially used for high current applications and features a manually operated switch for tripping the circuit.
Most conventional household breakers are fixed-trip MCBs, which cannot adapt to variable high-current industrial loads. In contrast, Ac Mccb products support adjustable tripping settings, flexible installation methods, and high short-circuit breaking capacity, making them the preferred protection solution for low-voltage main distribution circuits and heavy-duty equipment. Zhejiang C&J Electrical co., ltd. (referred to as C&J Electrical) launches the CJMM3 series dual adjustable MCCB, a high-performance Mccb designed for full-scenario low-voltage power distribution protection.
Basic Definition and Core Functions of MCCB
A Moulded Case Circuit Breaker (MCCB) is a mechanical switching device with molded insulation housing, dedicated to low-voltage AC power distribution systems. Different from small-capacity MCBs, Mccb Circuit Breakers focus on high-current circuit protection and support customizable tripping parameters, which can be adjusted according to actual load requirements[2][7].
The core functions of Mccb Electrical equipment include connecting and carrying normal operating current, as well as breaking abnormal current under overload and short-circuit faults. Some models support undervoltage protection through accessories, which can automatically cut off the circuit to protect lines and electrical equipment from damage caused by grid abnormalities[4][10]. Widely used in AC power distribution scenarios, Ac Mccb has become indispensable equipment for industrial power distribution, building electricity, and new energy supporting systems.
C&J Electrical CJMM3 Series MCCB Product Overview
The CJMM3 series dual adjustable moulded case circuit breaker developed by C&J Electrical is a new-generation high-performance Mccb complying with IEC60947-1 and IEC60947-2 international standards. This series is specially optimized for low-voltage distribution lines, supporting adjustable overload and short-circuit tripping parameters, adapting to complex and variable load environments.
As a professional Ac Mccb product, CJMM3 covers frame current grades from 125A to 630A, fully meeting the high-current protection needs of industrial equipment, building main power distribution, and commercial power systems. It supports multiple installation methods and tripping types, with complete specifications and strong scene compatibility. The whole series belongs to Utilization Category A, suitable for terminal power distribution protection without intentional short-time delay selectivity requirements[2][4][7].
Structural Characteristics
CJMM3 series Mccb Circuit Breakers have scientific structural design and stable mechanical performance, with outstanding advantages in line protection and equipment safety monitoring:
- Multi-Fault Protection Mechanism: It can connect, carry and break current under normal circuit conditions, and bear and break abnormal current within a specified time when overload, short circuit, and undervoltage faults occur, effectively protecting low-voltage distribution lines and terminal equipment.
- Complete Frame Current Specifications: Covering 125A, 160A, 250A, 400A, 630A frame grades, with a rated current range of 16A to 630A, realizing full coverage of medium and high current distribution scenarios.
- Wide Voltage Adaptation: Support rated working voltages of 400/415V and 690V, adapting to conventional low-voltage AC power grids and industrial high-voltage distribution systems.
- Hierarchical Breaking Capacity: Equipped with multiple breaking levels including 20kA, 36kA, 50kA, 70kA, 75kA, matching the short-circuit protection requirements of different power distribution levels.
- Flexible Tripping Types: Optional single magnetic type and thermal magnetic release types, meeting the protection needs of conventional resistive loads and motor inductive loads respectively.
- Diversified Installation Methods: Support fixed, plug-in, and drawer-type installation, adapting to different cabinet structures and on-site construction requirements.
- Wide Industry Adaptability: Widely applicable to low-voltage power consumption scenarios such as electric power engineering, construction industry, industrial production, and OEM supporting equipment.
Working and Installation Conditions
CJMM3 series Mccb Electrical products have excellent environmental adaptability and can operate stably in complex working conditions:
- Normal Operating Temperature: Standard working temperature ranges from -5°C to +40°C. It can also adapt to extreme temperatures of -40°C ~ -5°C and 40°C ~ 70°C; derating use is required when the temperature exceeds 40°C, referring to the temperature derating coefficient table.
- Storage Temperature: The allowable storage temperature is -40°C ~ +70°C. If stored at an ultra-low temperature beyond the normal working range, the product needs to be placed in the standard working environment for at least 24 hours before use to ensure stable performance.
- Humidity Adaptability: At a maximum ambient temperature of +40°C, the relative humidity shall not exceed 50%. Higher relative humidity is allowed at lower temperatures, for example, 90% humidity at +20°C, adapting to conventional humid working environments.
- Environmental Grade: Pollution Degree III, front-side IP40 protection grade, suitable for general industrial and commercial indoor distribution environments.
Core Technical Data
CJMM3 series Ac Mccb has standardized and complete technical parameters, fully complying with international industry standards:
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Technical Items
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Specifications
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Product Type
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CJMM3-125~630A
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Pole Number
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3P
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Rated Current Range
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16A~630A
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Rated Operational Voltage
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400V/415V/690V
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Rated Insulation Voltage
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800V/1000V
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Impulse Withstand Voltage
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8kV/10kV
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Operating Frequency
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50/60Hz
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Utilisation Category
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A
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Executive Standard
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IEC60947-1, IEC60947-2
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Electrical Life
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5000/3000 cycles
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Protection Grade (Front)
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IP40
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Pollution Degree
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Class III
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Release Type
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Single magnetic trip / Thermal magnetic trip
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Application Scenarios
With adjustable tripping function, high breaking capacity and wide environmental adaptability, CJMM3 series Mccb Circuit Breakers are widely used in various low-voltage AC power distribution scenarios:
- Industrial Power Distribution: Used for main circuit protection of factory workshops, mechanical equipment, and production lines, providing overload and short-circuit protection for high-power industrial equipment.
- Construction & Building Engineering: Applied to low-voltage distribution boxes and power distribution cabinets in commercial buildings, residential communities, and office buildings to ensure safe and stable power supply for buildings.
- Electric Power Supporting Projects: Suitable for terminal distribution protection of power grid low-voltage lines, supporting stable operation of power transmission and distribution systems.
- OEM Complete Equipment: Matched with automation equipment, power distribution complete sets, and electromechanical supporting equipment, providing standardized safety protection for terminal electrical equipment.
Product Advantages
Compared with ordinary fixed-trip Mccb products on the market, C&J Electrical CJMM3 dual adjustable MCCB has prominent comprehensive advantages:
- Dual Adjustable Protection: Supports adjustable overload and short-circuit tripping parameters, which can be flexibly set according to actual load characteristics, solving the problem of fixed protection parameters of traditional breakers and improving system matching accuracy.
- Strong Short-Circuit Resistance: Multiple breaking capacity grades are optional up to 75kA, which can resist instantaneous short-circuit current impact and effectively avoid equipment burnout and line fire accidents.
- Wide Specification Coverage: Complete frame and current specifications, covering 16A-630A full current range, adapting to low, medium and high power load scenarios.
- Flexible Installation & Strong Adaptability: Three installation modes optional, wide temperature and humidity adaptation range, stable operation in complex industrial environments.
- High Safety & Durability: IP40 front protection grade, Class III pollution resistance, long electrical service life, stable and reliable long-term operation.
- Customization Service Supported: C&J Electrical provides professional OEM/ODM brand customization services with multiple product specifications, meeting diverse customer application needs.
Contact Us
CJMM3 series dual adjustable Ac Mccb launched by C&J Electrical is a high-performance low-voltage protection device integrating adjustable protection, high breaking capacity and wide adaptability. It fully meets the safety protection needs of industrial, construction, electric power and OEM supporting low-voltage distribution systems.
If you have any questions about product selection, parameter matching, installation and use, or need to know more about OEM/ODM customization services, please feel free to contact us. C&J Electrical will provide you with professional technical support and thoughtful after-sales service.
Post time: Jun-01-2026