MCB (Miniature Circuit Breaker)

What is Miniature Circuit Breaker (MCB)?

MCB (Miniature Circuit Board) is a safety device with significant applications in both commercial and residential areas. This device is an electro-mechanical circuit protection device. Through an automatic safety mechanism, it prevents electrical circuits from being damaged by excessive current flow.
The MCB operates automatically, which means that if a short circuit or overcurrent occurs, the MCB will trip, interrupting the power supply and preventing any damages from occurring. Despite this, these devices are sensitive to even the smallest variations in current and can detect minute levels above the safety limit. An MCB interrupts a circuit when it is overloaded or shorted.

An MCB can be used as a substitute for a fuse in household applications. Over-fuses for MCBs have the advantage of being reusable even after an overload, or short circuit interrupts the circuit.

A Miniature Circuit Breaker (MCB) is a device that uses an electromagnetic device encased in a molded insulation enclosure. Its primary function is to switch the circuit, which means that it opens the circuit (connected to it) if the current passing through it (MCB) exceeds its setting. Like a normal switch, it can be manually turned on and off.

MCBs operate based on the overcurrent magnitude, determining how long they are active. As a result, they are operated whenever overloads are present for a long enough period to threaten the circuits they protect.

In this way, MCBs are not affected by transient loads such as surges in switch currents and motor starting currents. In addition, these devices are designed to handle short circuits within 2.5 milliseconds and overloads within 2 seconds to 2 minutes, depending on the current level.
In addition to single-pole MCBs, double-pole MCBs, three-pole MCBs, and four-pole MCBs are produced in various pole arrangements with different fault current levels.

In most cases, MCBs are linked into two-pole and three-pole versions, which ensure complete circuit isolation in case of a fault on one line. This feature will benefit three-phase motor protection with single phasing.

They are rated for DC supply at 220V and AC supply at 240/415V (single and three-phase) with different short-circuit current capacities. Single-phase devices can typically handle 100 A current loads. In some MCBs, the tripping current capacity can be adjusted; in others, it cannot since the load current or short circuit rating is fixed.

In addition to performing local control functions, MCBs are used to isolate switches from faults and provide overload protection for installations and equipment.

Types of MCBs

Various MCB types are available, including types A, B, C, D, K, and Z. Types B, C, and D are three essential variations. Each is built to respond to the potential power of electrical surges in various environments. These fluctuations may also be referred to as “tripping characteristics” or “overcurrent characteristics” and are commonly known as their “trip curve.”

Let’s see how each primary type differs from the others:

B-Type MCBs

• When the current passing through reaches three to five times the rated maximum, or “rated load,” Type B circuit breakers trip.
• This type of MCB is the most delicate and intended for use in low-voltage commercial and residential situations where current surges are most likely to be minor.

C-Type MCBs

• When using more powerful electrical equipment in areas where surges are anticipated to be more significant, such as in commercial and industrial settings, Type C circuit breakers are employed.
• Usually, they trip at five to ten times the rated current load. Small electric motors and fluorescent lighting are two examples.

D-Type MCBs

• The least sensitive MCBs are D-types, which only turn on when the current exceeds the acceptable maximum by ten to twenty times.
• Heavy-duty commercial and industrial devices that occasionally experience very large current surges are designed to use D-rated MCBs. Examples include X-ray machines, big motors, welding equipment, and uninterruptible power supply systems.

K-Type MCBs

• This type of MCB trips between 8 and 12 times the full load current. When the current reaches eight to twelve times its recommended maximum, these will trip. They are an excellent option for motors.
• In Type K MCBs, the circuits like motors, transformers, and auxiliary circuits are protected and controlled against overloads and shorts.

Z-Type MCBs

• These MCBs are extremely sensitive, tripping even when the current is just 2 or 3 times greater than the rated load. As a result, they are employed in more delicate, short-circuit-prone electronics like semiconductors.
• Type Z MCBs are used to protect electronic circuits from weak and long-term overloads and short circuits.

How Does an MCB Work?

Miniature circuit breakers utilize a moderately robust mechanical mechanism to reduce failures and false alarms. They are activated by overcurrent, which is an electrical current that exceeds a predefined safe current.

A bimetallic strip inside the MCB bends, heats up, and trips when too many current flows through it. During this process, a switch is flipped, separating the electrical contact points and thereby containing the arc (electrical discharge). Next, an arc chute divides and cools the arc by using an insulated metal strip. The contacts will close once the fault has been rectified and the MCBs reset.

The purpose of an MCB is to protect against both overloading and short-circuiting. Each of these detection procedures differs from the other. For example, the bimetallic strip uses thermal operation to offer overload protection, whereas the tripping coil uses electromagnetic operation to give short-circuit protection.

In the event of a particularly high discharge, the MCB will trip (activate) in less than one-tenth of a second. The component will take longer to react when the overcurrent is closer to safety limits.

So, where does MCB find its uses?

Miniature Circuit Boards are the most reliable solutions for maintaining electrical safety in residential, agricultural, and industrial settings. These industries include manufacturing, healthcare equipment, automotive electronics, and consumer products. The main reasons for their effectiveness are their ability to perform in extreme operating environments and withstand higher temperatures, vibrations, and humidity.

1. Residential Uses:  Miniature Circuit breakers effectively prevent damage due to power fluctuations in homes. They can be connected to electrical panels to safeguard home electrical systems from overheating.
2. Agricultural Uses: India is largely an agriculture-driven economy, with technology taking over traditional agricultural practices. In order to increase power consumption and irrigation efficiency, farmers are using new-age equipment. An MCB is an effective way to protect and enhance the performance of agricultural equipment.
3. Industrial Uses: MCB is vital for the efficient functioning and maintaining the safety of the electric equipment by optimizing the electrical flow.

What makes BCH MCB better than other options?

BCH has been instrumental in devising reliable Miniature Circuit Breakers that meet every safety standard. Our high-performing MCB conforms to all industry standards for effectual output and multiple commercial applications. MCBs are preferred due to their ease of use and relatively simple mechanism. This makes MCB the most reliable and safe alternative to traditional fuses. BCH ensures that all industrial and safety standards are followed while manufacturing these MCBs. Some of the essential benefits of BCH MCB are:

1. Easy mounting: BCH MCB can easily be installed either by mounting on DIN rails or directly fitting into the panels. Due to their accessibility in various sizes and shapes, it is relatively simple to integrate them into installations or electrical systems.
2. Ingress Protection: IBCH MCB provides a higher level of safety. They have a good IP rating of IP 20 and thus are safe to use and operate.
3. Wide range of Current Rating: BCH MBCs are available in a varying range (SP, SPN, DP, TP, TPN & FP) of current ratings ranging from as low as 0.5A to 63A..
4. High Performance: BCH MCB can interrupt the current of up to 10KA without incurring any damage and effectively handle an electrical arc. At the same time, they can withstand an impulse voltage of 4KV. It makes our MCB the most reliable choice for residential and industrial applications.
5. Longer Life Span: BCH MCB provides several years of efficient performance. With every pole in the MCB secured individually, these MCBs have a longer service life and ensure reliable performance throughout their life. The trip mechanism functions effectively for their entire life and provides safety against possible fire hazards if a fault occurs. Thus, increasing the lifespan of the equipment.
6. Compact and efficient design: BCH MCB has the most efficient design to accommodate two functions of current limiting and isolation in the same unit. Also, their compact design saves a lot of space.
7. Interchangeable outlets: BCH MCB is designed in such a way as to enable users to interchange the line and load terminals. Thus, making them suitable for reverse-feed applications.
8. Wide range Application: BCH MCB have a tripping curve of B & C type, thus making them suitable for both low and high current load applications where current surges are less, like lighting, residential use, electronic equipment, and industrial applications where higher voltage current surges may be experienced.
9. Adhering Industry Standards: BCH MCB are manufactured with adherence to standards IS/IEC 60898-1 for the range of 6A-63A and IS/IEC 60947-2 for the range of 0.5A-5A.

MCB is a circuit protection device that protects a circuit or a piece of equipment from damage due to faulty conditions such as overloads and short circuits. The meaning of using it in a circuit is not to stop overloads or short circuits from happening. Instead, it is to protect the circuits from more significant damages caused by them.

BCH Electric Limited is committed to delivering products that meet the higher industry standards in terms of safety, dependability, and performance. In addition, it assures higher service life and convenience of application. We promise the guarantee of secured electrical systems in all industries and households with our trusted MCB.