what is mcb and mccb？

Comparison of core differences
Rated current range

Molded case Circuit Breaker: usually 6-800A, some high-end products can reach 1600A

Frame circuit breaker (ACB): generally 630-6300A, suitable for large capacity main circuits

Structure and Installation

Plastic shell circuit breaker: using a plastic shell, compact structure, sealed internal components, mostly non repairable, flexible installation

Frame circuit breaker: Adopting a metal frame and modular design, supporting drawer style installation for easy maintenance and component replacement

Protection function

Molded case circuit breaker: equipped with long delay and instantaneous protection; Electronic models can be equipped with four stage protection, including short delay and ground fault protection

Frame circuit breaker: comes standard with four stage protection (long delay, short delay, instantaneous, ground fault), and some intelligent models support functions such as communication, measurement, and regional interlocking

Breaking ability and withstand current

The short-circuit breaking capacity and short-time withstand current (Icw) of the frame circuit breaker are significantly higher than those of the molded case circuit breaker, making it suitable for high fault current situations such as main incoming lines

Application scenarios

Molded case circuit breaker: commonly used for branch protection, such as distribution cabinet outgoing lines, motor control, etc

Frame circuit breaker: mainly used for primary distribution positions such as power main switch, bus tie, large capacity feeder, etc

Usage category

Molded case circuit breaker: usually Class A (no short delay, no Icw value).
Frame circuit breaker: usually Class B (with adjustable short delay and Icw value)