Insulated case circuit breakers (such as MCCB) differ from air circuit breakers in structure, function, application scenarios, etc., as follows:
I. Definition and Classification
Molded Case Circuit Breaker (MCCB)
Definition: A low pressure protective device with a high strength plastic casing, containing contact system, arc extinguisher, buckle release device and operating mechanism.
Classification: 1P, 2P, 3P and 4P by pole number; thermal-magnetic (basic protection) and electronics (high precision adjustable) by stroke unit type; standard, high interruption and restricted flow type by ability.
Air Circuit Breaker (ACB)
Definition: circuit breaker with air as an arc extinguishing medium whose contacts open and close in air at atmospheric pressure.
Classification: Includes box circuit breakers (large capacity, for power circuits) and die shell case circuit breakers (small capacity, for load circuits).
Note: Molded case circuit breakers (MCCBs) are commonly referred to as "air switches" because they use air to extinguish an arc. Strictly speaking, however, there are more types of air circuit breakers (such as framework circuit breakers).
ii. Core differences
Comparison Dimensions: Molded Case Circuit Breaker (MCCB) Air Circuit Breaker (ACB)
Structure and size: plastic shell, small size, light weight, compact structure. Steel frame, small size, large capacity.
Rated current range: 6A to 1600A, suitable for low and medium voltage applications. Generally above 630A, suitable for high current circuits.
Cracking Capacity: Cracking ability is strong, but lower than frame circuit breakers. High breakability, suitable for high short-circuit current applications.
Protection Functions: provides overload, short circuit, undervoltage protection, and can be equipped with electronic tripping device. More comprehensive protection features, including support for intelligent controls and communication interfaces.
OPERATIONS: Manual or electric with support for remote control. Manual or electric operation to support automation system linkage.
Application: Industrial motor control, commercial distribution, residential lighting, etc.. Large power system, main switch of industrial equipment, power plant, etc.
Price: relatively low, good value for money. Higher prices, but more reliable.
III. Comparison of functions and applications
Molded Case Circuit Breaker (MCCB)
Functions:
Overload Protection: Thermal stroke detects the thermal effect of current to prevent the device from overheating.
Short-circuit protection: electromagnetic travel can quickly interrupt short-circuit current.
Undervoltage Protection: Automatic tripping when voltage is below rated.
Application:
Industry: Factory power system, motor control.
Commerce: Distribution system for shopping malls and office buildings.
Residential: Lighting and socket protection for homes and apartments.
Air Circuit Breaker (ACB, Framed Example)
Functions:
High-volume interruptions: short-circuit currents capable of interrupting dozens of kilowatts.
Intelligent control: Integrated electronic vehicle departure device to support remote monitoring and fault diagnosis. Multi-level protection: Supports ground fault protection, inverter power protection, etc..
Application Scenarios:
Large industrial equipment: such as steel mills, chemical plants, such as the main power switches.
Power plants and substations: control and protection of high voltage transmission systems.
Data centers: Ensure reliability and security of power supply.
IV. INTRODUCTION Selection highlights
Molded Case Circuit Breaker (MCCB)
Rated voltage: Match circuit voltage (e.g. AC 400V).
Rated current: Maximum working current of a ≥ circuit.
Cutoff capacity: Anticipated short circuit currents in ≥ circuits.
Type of stroke unit: Thermal or electronic according to protection requirements.
Extremes: Single-phase circuits choose monopoles or bipoles, and three-phase circuits choose tripoles or quadpoles.
Air Circuit Breaker (ACB)
Rated current: Choice based on load capacity (e.g., 1600A, 3200A).
Crushing capacity: Prefer high breaking capacity (e.g. 100kA).
Smart features: Choose whether to support communication interfaces and remote controls as needed. Installation method: fixed, drawers or plug-ins, selected according to the installation space.
