MCB is the acronym used for the miniature circuit breaker and is commonly used in our day to day lives. Its primary function is to break the circuit when the current flowing through the circuit reaches past a certain set limit. In conditions such as short circuit or overload, these devices trip by themselves hence saving the house by the damages caused by a short circuit or overload or as the case may be. The mechanism of MCB has 3 possible positions, ‘ON’, ‘OFF’, and ‘TRIPPED’, hence the breaker provides manual means of opening and closing of the circuit. MCB is a kind of a better version of a fuse.
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MCBs work on a time-delay tripping mechanism. This means that they function whenever there is an overload or higher flow of current for a longer duration of time, the duration which can hamper the normal functioning of the circuit. The time duration if exceeds a certain value the MCB trips and breaks the circuit thus rendering the overload dysfunctional in damaging the appliances and further circuit.
What is MCCB?
MCCB is the short form for a moulded case circuit breaker. It is used to protect the electric circuit from the flowing of excessive current which can further cause damages such as overload and short circuit. They are being used for a wide range of frequencies with the current rating up to 2500A and adjustable trip settings. MCCB provides overload protection via the temperature-sensitive component. These are usually used in PV systems in place of miniature circuit breakers. These work on principles of electromagnetism and cam also be disconnected manually. MCCB’s are subjected to high current, therefore they need proper maintenance and can be maintained by regular cleaning, lubricating, and testing.
MCB’s trip characteristics may not be adjusted since they are mostly provided to low circuits with the MCB rated 100 amps with an interrupting rating of under 18000 amps. Whereas MCCB has the characteristics of the adjustable trip which is used in higher models. MCCBs provide amps between 2500-10 and their interrupting rating ranges from 10,000 amps to 200,00 amps. Hence this states that MCB is usually used for low energy requirements such as home wiring or small electric circuits, on the other hand, MCCB is more suited for high energy requirements.
MCB being rated under 100 amps doesn't come with the feature of the adjustable trip, hence they always cater low current circuit. Whereas MCCBs being rated from 10 to 2500 amps comes with an adjustable trip feature so they can cater for high current circuits
Although an MCCB possesses a higher capacity than an MCB, both are classified under low voltage circuit breakers and should respond to standards set by the IEC 947. For the sake of convenience, MCCB is equipped with a special feature of being tripped only by remote as their units have electrical motor operators. Whereas MCB lacks this feature.
MCCB is said to be more suited for higher energy due to the possession of better capacity than MCB, whereas MCB is usually provided for low energy requirements, hence they are best suited for them.
Obviously, when it comes to home use or some light work, the MCB is better preferred due to low energy requirements. On the other hand, when it comes to industrial use or any other heavy-duty requirements, MCCB is the best suited.
Did You Know?!
The miniature circuit breaker was invented by Stotz-Kontakt, a company that was established in Mannheim, Germany, in the year 1891.
1. How is MCB better than a fuse?
Nowadays MCBs are much more commonly used in low voltage electrical requirement networks instead of fuses. The MCB has many advantages compared to a fuse, following are some of them: -
MCB switches off the electric circuit automatically in case of short circuit, overload or any abnormal conditions as it is more sensitive to change in current.
It is much easier to detect a fault in MCB rather than a fuse. When the operating knob comes to it’s off position while tripping, the faulty zone of the electrical circuit can easily be identified. Whereas in the case of a fuse, the fuse wire has to be checked by opening the fuse grip (often called cutout) from the fuse base, to confirm the blow of the fuse wire.
To handle an MCB is safer than to handle a fuse, there are more chances of getting hit by an electric shock while operating a fuse than that in MCB.
2. What are the advantages of MCCBs as a back-up protective device?
MCCBs are necessary for making, carrying and breaking currents between separate contacts under normal circuit conditions and also under abnormal circuit conditions (like overload or short circuit). Following are some of its advantages: -
MCBs are ‘compact’, Hence it provides a significant space for panel design.
The device’s maintenance fee is absolutely free and recurring costs are also very less.
MCCB prevents a device from failure in faulty or abnormal conditions such as short circuit or overload or as the condition may be.
MCCB usually takes much less time to reset and to switch on when it trips down during the faulty/abnormal condition.
MCCB has the ability to clear several faults, before it is due for replacement.