Transformer Basics and Types

What are Transformers?

Transformers are electronic devices which transfer energy between two or more circuits through the process of electro magnetic induction. Scientist Faraday designed few laws which can be explicitly applied to transformers to efficiently change AC voltages from one voltage level to another voltage level within the same power networks. A transformer varies in sizes starting from a RF transformer which is less than a cubic centimeter in volume to very large power grids weighing hundreds of tonnes. Since it's inception in the year 1885, it has become a reliable source for the efficient supply and conservation of electrical energy. 


Working Principle

Transformers work on the Faraday’s law of electromagnetic induction which says “Rate of change of flux linkage with respect to time is directly proportional to the inducted electromagnetic force in a coil or a conductor”. Basically, the mutual induction between two winding is accountable for the transformation action in an electronic transformer. A transformer basically carries out the functions that are listed below-

  1. It transfers electric power from one circuit to the other.
  2. It transfers electric power without changing the frequency.
  3. It transfers by making use of the principle of electromagnetic induction.
  4. It links two electrical circuits using mutual induction.



Construction of transformers

Construction of Transformer

For the construction of a transformer, two coils that have mutual induction capacity are needed along with a laminated steel core. Both the coils are then insulated from each other and later from the steel core.  A suitable container may be required by the device so as to assemble the windings and core. It will work as a medium for the insulation of winding and core. Apt bushings made out of capacitor or porcelain must be used in order to bring out the terminals of the winding from the tank. For all the commercially used transformers, the core is made of steel laminations that offer a constant magnetic path with a lesser air-gap. The steel must be highly permeable and must be made out of high silicon content and shall also be heat treated. When the core is effectively laminated the rate of current loss can be reduced. The lamination may be done using an oxide layer or plate varnish on the surface.

Different types of Transformers

Depending on the requirement and the usage, various electrical transformers are designed and executed. Let us now see some of the different types of transformers and their usage in detail: 

1. Current Transformer- The current transformers are basically used in electric sub-stations for transforming the high magnitude voltages to low magnitude voltages and currents that are apt for the purposes of protection and metering.  This transformer is basically two types- wound core type and ring type. The wound core type has a primary winding of one or more turns on the core while the ring type does not have a primary winding.     

Current Transformer    Power Transformer

2. Power transformer: There are strict international guidelines in place when it comes to the use design and location of distribution transformers. As the name suggests, the application of this type of transformer is to distribute the electrical energy from the source of production to the different other sub stations. Similarly a power transformer is used in the transfer of electrical energy from the generator i.e. the production plant to the other primary circuits in a smooth and safe way.

3. RF transformer- It is also known as the Radio-frequency transformer that is used for describing VHF, RF and UHF frequencies. The construction of these transformers varies at each frequency.

RF Transformer                  Instrument Transformer

4. Instrument Transformer-  These instrument transformers are basically high accuracy devices that are used for the isolation or transformation of current and voltage levels. These are commonly used to operate instruments and may sometimes be used in isolation transformers as well.

Other types of transformers

5. Auto transformers: the basic and the first type of transformer is the auto transformer. In this type, the wiring is common to both primary and secondary circuits. Hence it doesn't require a seperate wiring for the sources. 

6. Capacitor voltage transformer: it is the second type in which capacitor device is used to reduce high voltage before its use in the primary winding. It is usually applied in the domestic consumption of electricity to counter the fluctuation of current and to maintain uniformity across the spectrum. 

7. Phase angle regulation transformer: The 3- phase current is the best example of a phase angle regulation transformer. It is a specialized transformer which is used to control the flow of electrical current on 3 phase electrical transmission networks. One of the phase acts as a regulator and the other phase depends on it for the transmission of energy. 

8. Scott T- transformer: this type of transformer is used to phase out the power from a 3- phase transformer to a 2-phase transformer and vice versa.its application is used in the upgrading and down grading of the phase. It is a temporary transformer involved in the change of phases only and its use is limited. 

9. Polyphase transformer: it is the name given to any of the transformer with more than one phase. It is a generalized name used for many transformers. 

10. Grounding transformer: These types of transformers are used in the grounding of the three phase circuits to create a neutral wire in the 3-wire system. A zig zag grounding wiring system is used in order to create a neutral current for safety and maintainance concerns. 

11. Leakage transformer: it is a name given to those transformers which has loosely coupled windings. This type of setting provides it with an inherent current limitation due to its loose winding. It is generally used for arc welding and high voltage discharged lamps. 

12. Resonant transformer: transformers which use the property of resonance to generate high voltage currents. Fluorescent lamps are an example of a resonant transformer. 

13. Audio transformer: as the name suggests, it is used in the transmission of audio generally an amplifier or a powerful music system. 

Applications of Transformers

Now that we have learned about the different types of transformers, let's see some if the common applications of the transformers. 

  1. The basic use of it is to increase the voltage in order for it to transfer high voltages from the unit to long distance power stations through copper wires. 
  2.  Economical transfer of power is possible only with the use of transformers as wires have high resistance and a lot of energy is wasted in the process of transmission. 
  3.  It is Because of the transformers that energy can be supplied to remote areas without the actual station of the power plant in the nearby vicinity. 
  4.  It acts as a medium of seperation of the power station from the end consumer. Hence, reducing the risk factors associated with the supply and usage of current.