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MCB vs MCCB

What are the differences between MCB and MCCB?

These two circuit breakers serve a common purpose, to automatically open the circuit during short circuit fault. This article will tackle more about their differences in terms of construction and application.

MCB

MCB or Miniature Circuit Breaker. It’s a protective device that automatically cut off the power during abnormal conditions such as short circuit, over current and overload. It has a bimetallic strip that will react based on current passing through the circuit and will bend as current rises. It’s attached to a mechanical mechanism that will cause the breaker to trip.

ABB 2-Pole MCB

In industrial application, this type of breaker is commonly used for control circuits and small utility loads such as Air-conditioning unit, lighting, etc. It’s also commonly used for residential applications as it’s easy to use and don’t have maintenance cost.

MCB are smaller in sizes and can be orders with different numbers of poles. It is sized based on load with utility factor considered. Tripping curve and application must be checked on selecting your proper MCB.

It can be attached with disconnects switches and handles too. Some have provided holder to allow easy Lock-out Tag-out.

MCCB

MCCB or Molded Case Circuit Breaker is a type of electrical protection device that is commonly used when load currents exceed the capabilities of miniature circuit breakers to cut-off the circuit. MCCB have higher ampere-frame rating than MCB. Used switch on/off the circuit and to protect from overload and overcurrent. They are also used in applications of any current rating that require adjustable trip settings, which are not available in plug-in circuit breakers and MCBs.

ABB SACE Tmax

This type of circuit breaker is commonly used as main breaker for distribution boards, motor power circuit, etc. It’s also usually attached with disconnect switches or panel doors for safety.

It’s usually bigger in size as it is commonly used for Distribution Board Main Protection or for MCC Main Breaker.

It’s sized based on motor power rating based on nameplate and standard full load current. If it’s an Inverse-Time Circuit Breaker, there will be circuit breaker calculation where we will consider 250% as multiplier for your computed Full Load Current.

It also comes with different numbers of poles and can be attached with different accessories such as power disconnect switches, Lock-out Tag-out, etc. Tripping curve must be considered on selection. However, there are MCCBs where you there are adjustable current settings and timings for wide range of use.

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