Full form of MCB:- full forms of MCB include the following
#1 Full form of MCB= Miniature Circuit Breaker
An MCB (Miniature Circuit Breaker) is a mechanical switching device that is capable of generating, transporting and breaking currents under normal circuit conditions and also performing, transporting for a specific time and breaking currents automatically under specific abnormal circuit conditions, such as those of short-circuit. In summary, MCB is a device for protection against overloads and short circuits. They are used in residential and commercial areas.
Actuator lever; It is used to trip manually and reset the circuit breaker. It also indicates the state of the circuit breaker (on or off / tripped). Most breakers are designed so that they can trip even if the lever is held or locked in the “on” position which is sometimes called the “free trip” or “positive trip” operation.
– Actuator mechanism: It actually forces the contacts together or apart.
– Contacts – Allow current by touching and breaking the current when separated.
– Bimetallic strip.
– Calibration screw: After assembly, it allows the manufacturer to precisely adjust the trip current of the device.
– Arc Divider / Extinguish
Types of trips
A situation of slow and small overcurrent that causes the ampacity and the temperature of the circuit to gradually increase over time. This type of occurrence is categorized by a slight increase in the load (ampacity) in the circuit and is interrupted by the thermal trip unit of the switch.
Thermal trip units;
An electromechanical trip unit (thermal magnetic ) to open the breaker contacts during an over current event. The magnetic trip unit is current sensitive as well the thermal trip unit is temperature sensitive. Both units act independently and mechanically with the trip mechanism of breakers to open the breakers contacts.
The thermal trip unit protects against continuous overload. The thermal unit consists of a bimetallic element located behind the breaker trip bar and is part of the circuit’s current transport path. When there is an overload, the increase in current flow heats the bi metal and causes it to bend. When the bi metal bends, pull the trigger bar that opens the breakers contacts.
The time required for the bi metal to bend and trip the switch varies inversely with the current. Because of this, the tripping time becomes faster as the current increases in magnitude.
Overload protection is applicable to any installation, conductor or component that may be subject to over current’s of low magnitude but prolonged. Low magnitude, Over current’s of long time can be dangerous because they reduce the life of the conductor of the electrical installation and the components and, if left unchecked, could cause fires.
A situation of rapid and intense over current that increases the capacity of the circuit. This type of event is characterized by a dramatic increase in the load (current) in the circuit and is interrupted by the magnetic trip unit of the breaker.
Short circuit protection (magnetic trip units):
The magnetic trip unit protects against short circuits. The magnetic trip unit consists of an electromagnet and an armature. A large amount of current passes through the coils creating a magnetic field during short circuit that attracts the mobile armature to the fixed armature. The tripping of the hammer is pushed against the moving contact and the contacts are opened. The opening of the breakers contacts during a short circuit is completed in .٥ milliseconds.
B type MCB
This type of MCB will trip instantly at a speed of three to five times its nominal current. They are normally used for restive or small inductive loads where switching surges are very small.
They are used for the protection of restive loads such as light bulbs, heaters, etc., generally suitable for domestic applications. Therefore, these are suitable for light residential or light commercial installations.
C type MCB
This type of MCB will trip instantly at a rate of five to ten times its nominal current. They are normally used for high inductive loads where switching over voltages are high, such as small motors and fluorescent lighting.
In such cases, type C MCBs are preferred to handle a higher value of short-circuit currents. These types of mcb are used for the protection of inductive loads, such as motors, air conditioners, etc. are the devices which are the normal option for commercial and industrial applications.
D type MCB
This type of MCB will trip instantly at a speed of ten to twenty-five times its nominal current. They are normally used for very high inductive loads where high input current is very frequent. These are suitable for specific commercial and industrial applications.
They are mainly used for the protection of cables and highly inductive loads that have a high starting current, such as, for example, large battery charging systems, transformers, x-ray machines, winding motors, and some types of discharge lighting.
For High Current Device (MCCB)
The molded case circuit breaker (MCCB) is similar to the MCB family, which is portable and related to safety. The inequality in them is mounted in a shooting device toolbox. The housing acts both as an outer housing and to keep the internal components of the circuit breaker in the correct position.
These housings are made of various types of flame retardant and electrically insulating plastics. MCCB can automatically cut off the power supply in case of overload and short circuit. It is intended for higher nominal currents and is often used in industrial applications.
MCCBs are used generally in power distribution and protect low voltage distribution circuits, as well as motor loads. MCCBs can protect motors against overloads and short circuits. MCCBs can also provide under voltages, ground and phase errors. However, these functions are offered with additional accessories. MCCBs are used for general circuit protection. The overload, short circuit and trip delay time can be set according to the application.
The MCCBs are selected based on the maximum load current and the maximum short-circuit current that must be safely broken. When an MCCB is used as a backup protection for an engine, it can break the circuit when selected based on its full load current. When selecting the MCCB fuse for a motor, it must be selected based on the motor starting current.
The over current value of the MCCBs can be adjusted from 40% to 100% of their nominal value. Overload relay is required. When used in motor protection circuits, MCCBs can only protect against short circuits. Therefore, additional contractors and overload relays are required. Schultz is essential in these cases.
The difference, unlike MCB, is that MCCBs can be of the thermal / ferromagnetic / electronic trip type. Second, mainly protection against over current and short circuit. It can also provide protection against earth faults, residual currents, under voltage, etc.
They are available up to a nominal power of 2500 A. The activation level can be varied in MCCB adjustable trigger. Control from Remote place for its on / off is possible with additional accessories. MCCBs are commonly used for loads above 100 A and MCB below this level, as well as for motor protection circuits. Some MCCBs rely on micro controllers. Available in one, two, three and four pole versions.
Select the correct MCB:
The decision to use miniature circuit breakers type B, C or D for final circuit protection in residential, commercial, industrial or public buildings can be based on a few simple rules. However, understanding the differences between these types of devices can help the installer overcome unwanted tripping problems or make an appropriate selection where the demarcation lines are less clearly defined. It should be noted that the main objective of circuit protection devices, such as miniature circuit breakers and fuses, is to protect the cable downstream of the device.
The essential distinction between Type B, C or D devices is based on their ability to handle over voltage currents without tripping. These are typically input currents associated with fluorescent and other forms of discharge lighting, induction motors, battery charging equipment, etc.
It is important that equipment that has high input currents does not cause the circuit breaker to trip unnecessarily, and however, the device should trip in case of a short circuit current that could damage the circuit wires.
#2 Full form of MCB= Molecular Cell Biology
Molecular cell biology is the place where three scientific disciplines are meet: biochemistry, cell biology and genetics. The field explores the relationships between cellular processes and reactions, macro molecules and gene control pathways to answer a wide variety of scientific questions.
As, there is progression in the development of the biology tools, especially with the introduction of cutting-edge technology such as compound microscopes and electron microscopes, scientists began to explore the infinitely small components that make up the living world.
They discovered that organisms are made of cells and that those cells are made of even smaller components such as organelles and bio molecules. Thanks to these discoveries, biology quickly branched out into many sub disciplines. Three of these were essential for MCB to emerge as its own field of study.
– Cellular biology, which studies the structure and function of the basic unit of life.
– Biochemistry, which explores the chemical reactions and processes that make life possible.
– Genetics, which analyzes the way in which organisms inherit traits and regulate gene expression.
Molecular Medicine Emerges
Scientists can understand how programs and cellular reactions normally work, as well as the relationships between these processes and gene expression all due to the study of molecular cell biology. It can also reveal the reasons for the dysfunction in those programs, which can cause diseases. If scientists can find out why a disease occurs, they could discover how to reverse or prevent it.
This is the role of molecular medicine, which uses the information obtained through molecular cell biology to create new treatment options, including pharmaceuticals. Molecular medicine is closely related to personalized medicine.
This medical specialty investigates the genome of the patient to discover diseases for which the patient is at risk. Then, the health care provider can focus interventions to help the patient avoid or overcome these diseases.
By observing cellular programs and the reactions that take place within the cell, as well as the ways in which the cell regulates gene expression, molecular cell biology is one of the most promising areas of scientific study. From the perspective of the medical and healthcare consumer, the advances made in the MCB field are more than intellectually exciting. They point to a completely new way of looking at human health and disease.
#3 Full form of MCB= Master Cell Bank
An MCB is defined as an aliquot of a single set of cells that has generally been prepared from the selected cell clone under defined conditions, dispensed in multiple containers and stored under defined conditions. The MCB is used to derive all functioning cell banks (WCB). The test performed on a new MCB (from a previous initial cell clone, MCB or WCB) must be the same as for the MCB unless justified.
Biological products such as monoclonal antibodies and recombination proteins are produced in cultured cell lines of humans, lower mammals, insects and bacteria. These therapeutic producing cells are usually created through a process that involves:
- Gene Transfected or Transformation
- Expression screening
- Cellular expansion and characterization
While they are in culture, these cells must be passed regularly, which increases the possibility of genetic alterations, contamination or expression loss constructs as the cells divide. Therefore, for optimal drug production, it is essential that the cells pass as few times as possible and that the original high production clone is not lost or altered.
A Master Cell Bank (MCB) is produced from the original therapeutic producer cell line. It is preserved in multiple vials to avoid genetic variation and possible contamination by eliminating the total number of times a cell line is passed or handled during the manufacturing process.
These cell banks must be well characterized and tested to detect contaminants such as bacteria, fungi and cytoplasm before regulatory submission.
Cellular banking procedures
Manufacturers must describe the type of banking system used, the size of the cell banks, the container (vials, ampules or other appropriate containers) and the closure system used, the methods used for the preparation of cell banks, including the protectionists and the means used, and the conditions used for crop reservation and storage.
The procedures must be described by manufacturers in order to describe the procedures used to prevent microbial contamination and cross-contamination by other types of cells present in the laboratory, and the procedures that allow cell bank containers to be traced.
The description of the documentation system, as well as that of a labeling system must be included that can support the process of conservation, storage and storage recovery without loss of labeling information in the container.
General principles of characterization as well as testing of cell banks
The characterization and testing of stored cell substrates is a critical component of the control of biotechnological and biological products. The characterization of the MCB allows the manufacturer to evaluate this source with respect to the presence of cells of other lines.
Adventitious agents, endogenous agents and molecular contaminants (for example, toxins or antibiotics of the host organism). The objective of this test is to confirm the identity, purity and suitability of the cell substrate for use in manufacturing. In some cases, additional tests such as carcinogenicity or cardiology may be useful.
Proof of identity
Appropriate tests should be performed to determine that the stored cell is what is represented. Phenotype or phenotype characteristics can be used in identity tests. It is not considered necessary to do all possible tests. Identity tests are usually performed at the MCB. In addition, limited identity tests are usually performed at each WCB.
In most cases, the analysis of isoenzymes is sufficient to confirm the species of origin of cell lines derived from human or animal sources; Other tests may be appropriate depending on the history of the cell line. Other technologies can be substituted to confirm the species of origin, which include, for example, the cytogenetics of bands or the use of species-specific antisera.
For most microbial cells, growth analysis in selective media is usually adequate to confirm the identity of the host cell at the species level for the host cell bank and the transformed cell bank. For E. coli, where a variety of strains can be used, biological characterization methods such as phage typing should be considered as complementary identity tests.
A critical aspect of cell development and storage is the assessment that MCBs are biologically pure, that is, they do not contain adventitious microbial agents or adventitious cellular contaminants. The impact of selective agents and antibiotics on the detection of adventitious microbial contaminants should be considered when planning and conducting these tests.
Stability of the cell substrate
Another dimension of cellular characterization is the suitability for the intended use in production. There are two concerns for the stability of the cell substrate: consistent production of the desired product and retention of production capacity during storage under defined conditions.