Miniature Circuit Breakers (MCB): Functions, Working Principles, Types and Advantages
Nobody likes living in a dark room; electricity is crucial even though some might love the dark. Avoid a power outage with the best Miniature Circuit Breaker (MCB) in your home.
What is Miniature Circuit Breakers (MCB)?
Miniature Circuit Breakers (MCB) are electrical switches that automatically operate to protect the electrical circuit damage from current overflow, overloads, or short circuits. It is the electromechanical device used as a safety major in case of sudden overload or the current overflow.
MCB quickly detects the excess current and is designed to trip whenever there is an inevitable overload with chances of enormous damage. MCB interrupts the current flow as soon as the problem is detected. It breaks the supply of current whenever it exceeds the rated point.
MCBs are more sensitive towards faults and reusable even when there is an interruption from the circuit.
Functions of Miniature Circuit Breakers (MCB)
The primary function of the MCB is to break the circuit when the high voltage of the current is flowing from the conductor. It protects the appliance or the installation against short circuit faults and sustained overloading.
Miniature Circuit Breakers can be used for local control switching as an isolating switch. It is widely used for fuses in domestic installation as it is a more convenient option. MCB is designed in a tripping mechanism where the power circuit trips down whenever it exceeds the safe limit.
Also Read: THINGS TO KNOW BEFORE HIRING ELECTRICIAN
Working principle of Miniature Circuit Breakers (MCB)
Miniature Circuit Breakers (MCB) have three different mechanisms and two different effects.
MCB uses the Bi-metallic strip that causes the circuit to open in overload protection. It has an Electromagnetic strip for the case of short circuit protection.
Effects on which working principles of MCB are based are:
1. Thermal effect
2. Electromagnetic effect
Three different mechanisms of overload and short circuit protection are:
1. Bi-metallic strip
Whenever there is a situation of overload in the circuit, the Thermal effect of the Bi-metallic strip always takes over in the situation. Bi-metallic strips are arranged where a constant overload reigns over a long time, making the bi-metallic strip heated.
As the Bi-metallic strip overheats, it starts bending and releasing the mechanical latch. In such cases, displacement of the mechanical latch attached to the operating system causes a miniature circuit breaker to open.
2. Magnetic-Trip coil
Magnetic Trip Coil is used as protection in the cases of short circuits. The magnetic trip unit works on the mechanism of the Electromagnetic effect when a sudden wave of current flow in the short circuit through the magnetic trip coil activates the trip coil inside the MCB.
The plunger inside the coil starts to deflect because of it. In turn, it attracts upward and releases the latch inside the operating mechanism. The plunger hits the latch point and creates displacement because of the Magnetic Motive Force (MMF). The attached spring gets released, and the moving contractor results in the circuit's opening due to the latch point's displacement.
3. Manual Switching
Miniature Circuit Breaker also has the ON/OFF switch on the outer part. Such a switch helps to manually break the circuit and stop the current flow, which helps repair and maintain electrical activities.
It can manually happen even in the same cases as the displacement of the latch point. It occurs from the deformation of the bi-metallic strip or the increment in Magnetic Motive Force (MMF) in the trip coil. When we switch it back on, it automatically resets the operating system that has been displaced to its previous position.
Also Read: WHY SHOULD YOU HIRE A PROFESSIONAL OVER A LOCAL TECHNICIAN?
Advantages of Miniature Circuit Breakers (MCB)
Miniature Circuit Breakers are sensitive to the overcurrent flow and automatically cut off the power supply during faulty situations and overloads. When the MCB trips down, it automatically makes the switch operating knob go OFF. It makes us much easier to identify the faulty zone in the circuit.
1. Miniature Circuit Breakers (MCB)s are safer than fuse
The electrical circuit system is generally complicated. MCB is mainly used in low voltage electrical networks, which is much more convenient than the fuse and offers more protection and safety.
2. Offers better protection against electrical faults and is reliable
MCB is more reliable and is worth investing in them. It has a better way of protection than any other electric mechanical device.
3. Quick restoration of power supply
MCB operates via a switch which is an efficient way to allow quick restoration of the power supply by switching the knob ON in the operating knob.
4. Maintenance of MCB is much easier
MCBs are electrical switches that are automatically operated with the switches, making them easier to use and handle as per the situation.
Types of Miniature Circuit Breakers (MCB)
Every MCB has different tripping characteristics. It makes us easier to evaluate it for different applications.
According to their tripping mechanism, there are five types of Miniature Circuit Breakers (MCB).
1. Type B
Type B of MCB is mainly used in light commercial or residential applications. The connected loads are mainly domestic appliances and lighting fixtures with resistive elements in those applications.
Type B MCB has the trip level between 3 to 5 times according to their thermal rating. These are only useful to the normal resistive loads, not the high inductive current loads. The tripping of Type B MCB can occur in case of use of it in the high inductive appliances.
2. Type C MCB
Type C MCB has trip loads between 5 to 10 times at full current loads. It is used in industrial or commercial-type applications with higher chances of short circuit currents.
The connected loads are mainly fluorescent lighting and are inductive. Type C MCB is to control and protect the circuits against the inductive and resistive overloads with the low inrush currents.
3. Type D MCB
Type D MCB is used in higher-level industrial or commercial applications that use a very high current range. This type of MCB has high magnetic trip points, which prevent unusual tripping in high inductive applications. This type of MCB trips between 10 to 20 times of total load current.
The Type D MCB is to protect the overload against the high inrush current at the circuit closing.
4. Type K MCB
Type K MCB starts tripping when the current overload exceeds between 8 to 12 times the recommended point. This type of MCB is very suitable for the motor loads or the high inductive loads with the high inrush currents.
The Type K MCB controls and protects the overload of the current of the circuits like a transformer, motors, etc.
5. Type Z MCB
Type Z MCB trips between 2 to 3 times of total load current. This type of MCB is susceptible and used to protect sensitive devices like semiconductor devices.
The function of Type Z MCB is to control and protect the electronic circuits against weak and long-term overloads.
Types of MCB based on the numbers of poles
1. Single Pole (SP) MCB
Single Pole (SP) MCB is used to protect and switch for only one single phase of the current.
2. Double Pole (DP) MCB
Double Pole (DP) MCB protects and switches for both a phase and a neutral current.
3. Triple Pole (TP) MCB
Triple Pole (TP) MCB provides switching and protection only to the three phases of the circuit and not to be neutral.
4. Three Pole with Neutral [TPN (3P+N) MCB]
Three Pole with Neutral [TPN (3P+N) MCB] has protection and switching to all three phases of the circuit and the neutral as its part with a separate pole.
4. Four Pole (4P) MCB
Four Pole (4P) MCB is very similar to Three Pole with Neutral [TPN (3P+N) MCB]. It also has the protective release for the neutral pole.
Hope the post was informative. Let us know which types of MCB you are using in your home. Also, remember khoj sewa if you want the best electrician service in Nepal.