Before proceeding further to other subject matters, we should know about what exactly is an electrical transformer. Do you know?
Well, a transformer simply is an electrical device that transfers electrical energy with modified voltage and current from one circuit to another through magnetic coupling with no moving parts. Transformers are one of the most common and simplest electric devices in the world. However, designs and materials used to build these machines keep on improving with the availability of newer technologies. Just like in all places, use of transformers in Nepal is also a very common. Yet people generally don’t have a lot of knowledge about transformers even though it is used to supply energy in their homes and offices.
Transformers basically compromises of a single tapped winding in most cases. In some cases, two or more coupled windings are also used. A magnetic core is always present in transformers to concentrate the magnetic flux. If you are wondering why these machines are used so popularly, it is because these devices are essential for high-voltage power transmission. It is due to the use of transformers that long distance transmissions have become practical.
Construction of a transformer
Basically, a transformer is built using the simplest construction techniques. A transformer basically consists of three parts, a primary winding set, secondary winding set and a core. Generally, an iron core is used while building a transformer as it has higher permeability for magnetic flux as heat transfers better in iron than in air and other materials. The core is the medium for passing the magnetic flux from primary to secondary winding, so a core is one of the most important parts of a transformer.
With air as the core of a transformer, the coupling is not possible. However, with iron and other ferromagnetic material, coupling can be effectively done so it is used. As the flux of iron core is confined to a definite, good quality path linking and winding can be done.
While building a simple transformer, the two windings are brought close together, thereby improving the magnetic coupling as well as the efficiency of the transformer. Also, the core of a transformer is designed in a way to prevent circulation of electric current within the core itself. These eddy currents are tried to be prevented as much as they can as it causes heating issues and energy losses which reduces the transformer’s efficiency and productivity.
The highly permeable thin plates are assembled together to provide the required path with minimum magnetic loss. Due to the high resistivity of iron/steel, eddy currents are reduced as much as possible. The variations of the lamination’s thickness varies from 0.25mm to 0.5mm depending on what is needed.
During the construction of the core of the transformer, silicon steel is the material that is used most popularly. It is because this material is available at a very affordable price and can be got in a cost effective range. Also, silicon steel has features like high permeability and high flux densities, which is suitable for use in the core of a transformer. Compressed powdered ferromagnetic alloys known as ferrites are also used in the core of small transformers that are used for communication circuits at high frequencies and low energy levels.
Use of Electrical Transformers
-To Change Voltage and Current Level
To most important task of transformers is to transfer electricity by changing the voltage and current level. When transformers pass electric energy by managing the voltage and current, it helps to reduce the transmission loss. This results in creation of lighter transmission lines with less copper, hence resulting in overall economic profit during the overall circuiting. Also, these machines are used to step up / down the voltage for protection and safety measures of the consumers.
-To Provide Matching Impedance
Power in transformers remain unchanged, it’s only the voltage and current that changes before the energy is transferred. These can be used to convert the impedance of a load to a different level. Impedance matching is mostly used in audio systems where the impedance of speaker and devices are mismatched. Laws of Maximum Power Transfer Theorem is which states that power is transferred when impedance is matched.
-To Provide Galvanic Isolation
Transformers are famously used for separating or isolating two circuits that don’t have any physical connection between them. In such cases, with the use of transformers, energy is maintained through electromagnetic induction. In this way, both circuits become safe and also different potential can be maintained.
Types of electric transformers
Electronic transformers can be differentiated on the basis of many different categories. Voltage change, cooling types and applications are the basis in which electric transformers are mostly characterized.
According to the voltage, the electric transformers are differentiated into two types: step-up and step-down transformers. The step-up transformers increases the secondary voltage and hence the secondary current is decreased. On the other hand, step-down transformers helps to reduce the secondary voltage and hence the secondary current is increased.
With respect to the field of use, transformers are categorized as power transformers, distribution transformers, phase shifting transformers, traction type transformers and rectifier or HDVC transformers. Power transformers are used all the way from power plants to the distribution networks. Then, distribution transformers are used further in primary or secondary distribution network, and is designed for consumer end and continuous service. Traction type transformers is used for railing purposes to supply electric power through the rails. Example of use traction type transformers can be found in tram or train circuits. HDVC transformers are used in high voltage DC networks where there is also an AC network present. These types of transformers are a combination of a regular transformer + rectifier circuit or a regular transformer + inverter circuit.
On the basis of cooling, a transformer is characterized into liquid type and dry type. In liquid type transformers, the oil is used as a di-electric medium and also as a cooling medium. These types of transformers are usually more affordable and cheaper than other types of transformers. In dry-type transformer, aluminum and resin is used as the main materials. The main advantage of these transformers is that they minimize environmental combination and fire hazards. Also, less space and civil work is required to build and set up dry type transformers. However, users will have to pay a bit more to enjoy the facilities of dry-type transformers.
Although transformers are a must for power distribution, not many people know its importance and in many cases, it is even found that people have very minimal knowledge about it. Transformers may not be needed in case of all particular homes but in case of a big plant or organizations, having a transformer will really help to ensure proper distribution of power. Hence, we should know all we can about transformers and use them in a way which is most effective and fruitful. Also, don’t forget to contact BN Mahto Group, who are one of the best distribution transformer companies in Nepal, if you are in need for a top-of-the-line transformer. If you want to learn further about transformers, Read more.