What is MCCB? | Types | Operation and Mechanism - Electrical C & V


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01 May 2020

What is MCCB? | Types | Operation and Mechanism

What is MCCB?

The full name of the MCCB (Molded Case Circuit Breaker). Molded case circuit breaker is a type of Electrical Protection Device. MCCB is most commonly used when the load current is increased or decreased, or exceeds the circuit breaker's capabilities. They are also used in an application of an existing rating that requires adjustable trip settings, which are not available in Plug-in Circuit Breakers and MCBs.
What is MCCB? | Types | Operation and Mechanism
MCCB It works in both (50 Hz, 60Hz) Frequency range The main difference between a molded case and a mini circuit breaker is that the MCCB can have a current rating of 2,500A, and its trip settings are normally adjustable. An additional difference is that the MCCB is much larger than the MCB.



There are five different types of MCCB:

1. Type B
2. Type C
3. Type D
4. Type K
5. Type Z

1. Type B MCCB has the range of operating current which trips between three and five times in the overall rated current along with the operating response with 0.04 seconds of minimum and maximum limit of 13 seconds. Which is very much suitable for domestic applications along with the resistive load application with a lower amount of surge current.

2. Type C MCCB trips between 5 and 10 times the rated current input with response time from a minimum limit of 0.04 seconds and maximum limit of 5 seconds combining the application suitable for commercial or industrial purpose with inductive load applications for moderate surge current.

3. Type D MCCB trips between 10 and 20 times the total rated current input along with a response time of a minimum 0.04 seconds and maximum limit of 3 seconds combining the purpose of commercial or industrial applications along with the suitability of inductive capacitive load applications such as forms or motors or large vending motors.

4. Type K and Type Z MCCB trains between two and three times of the rated current input along with the response time of a minimum 0.04 seconds to a maximum limit of 5 seconds which is basically highly sensitive to short circuit and are mostly used for the production of highly sensitive devices such as semiconductor device is making it suitable for medical instruments along with the surge current level of very low at the subsidiary of distribution board for IT equipment.

The wide range of current ratings available from the Molded Case Circuit Breaker allows them to be used in a wide variety of applications. MCCBs are available with current ratings ranging from low values ​​ranging from 15A to industrial ratings such as 2,500A. This allows them to be used in both Low-Power and Hight-Power applications (Application).

Operation and Mechanism of MCCB

It works on the principle of thermal-magnetic circuit breakers. The MCCB has a bimetallic contact that contracts and responds as the temperature changes. Under normal operating conditions, the contact allows electric current through the MCCB. However, as the excess is reached, the contact heat and expansion will begin until the circuit is interrupted. Thermal protection against overload is designed with time delays to allow short duration overcurrent, which is a normal part of operation for many devices. However, any overlapping conditions that are higher than normally expected represent an overload, and MCCBs travel to protect equipment and personnel.

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