The transformer is the electric device which transforms electric energy between two and more circuits through the means of electromagnetic induction. The varying current is induced in the primary coil of a transformer which produces the varying electromotive voltage in the secondary coil of the transformer. The power induced in the primary coil of the transformer can be transferred between two coils by magnetic field.it is done without any metallic connection between the coils. The principle of the transformer operation was discovered in 1831 by Faraday where he develops Ferriday’s law of induction that explains the effect of electromagnetic induction. Base on the Faraday law of induction, transformer are used to decrease and increase the alternating voltage in the electric power application. From the moment of the invention of the transformer, it has been important in the distribution, transmission and the utilization of the alternating current of electrical energy. There is a wide range of the electrical transformer designs is seen in the electric power and electric application. It has a different size that ranges from RF transformer that is less than the cubic centimeter in the capacity of volume to power grid transformer that weighs hundreds of tons.
The varying current in the primary coil or winding it create the varying magnetic flux in the transformers core and the varying field of the magnetic impinging on the secondary coil or winging. The magnetic field at a secondary coil normally induces the varying voltage of EMF in the secondary coil because of the electromagnetic induction. Both coils, secondary and primary coils are winded around the core of endlessly magnetic permeability. Therefore all the magnetic flux passes the secondary coil and primary coil. Transformer current flow in the indicated direction depending on the polarity. The transformer coil voltage ratio is directly proportional to the number of coils that is winded on the core. Therefore if the number of coils in the primary winding is less than that of the secondary, the current induced in the primary coil will be less than that one produced by the secondary coil. Otherwise, if the secondary coil turns is less than the turns in the primary coil. The current induced in the primary coil will be more than that produced in the secondary coil. This is according to the law of the conservation of energy.
Types of the transforms
Electric transformers are of a different type depending on the design purpose. Despite the different transformer design that all transformer employ similar basic principles as it was discovered in 1831 by the scientist Michael Faraday and they share several main functional parts. The following are the type of the transformer:
Laminated core transformers: It is the common type of the transformer that is widely used in the transmission of electric power. It is applied to convert the primary voltage to lower voltage to that power that is efficient for an electronic device. This transformer is available in power that ranges from mW to MW. The insulator in the lamination reduces eddy current from being lost in the iron core. The transformer can be used in the split bobbin.
Toroidal transformer: it is the transformer which is ring-shaped, it is winded on the ring-shaped core. It takes minimal space of the device. It has a low magnetic field as compared to the rectangular transformer.
Autotransformer: it is a transformer that is tapped at various points in the windings. Voltage produces in the transformer varies depending on the point connected to the coil. The voltage produced increase with an increase of the turns of the winging at that particular point.
Polyphaser transformer: it is single build transformer but has multiple winding inside it. For example, the three-phase transformer has the three winding of the primary coil that induces its electromagnetic field to three winding of the secondary coil which is connected. Connection example of the transformer is wye-wye, delta-delta, delta-wye, and wye-delta.
Grounding transformer: It is the transformer that is connected to the delta form that is in the more polyphase system with supply accommodate phase to the neutral load by giving the return path of the currents to neutral. This transformer incorporates the single coiling transformer with the zigzag coiling configuration, but can also be created through wye-delta isolated coiling transformer connection.
Resonant transformer: it is the transformer that has the capacitor on both the winding or single winding across the coil that functions as tuned circuit. It is a transformer that is used at radio frequencies and electronic ballasts.
However, the other type of the transformer is as follows like ferrite core transformer, planar transformer, constant voltage transformer, stray field transformer, oil cooled transformer, and isolated transformer and many others that are designed base on different purpose to its functioning.
How the transformer works
Transformers is based on the simple fact of electricity. When alternating electric current travel through the wire, it normally generate the magnetic fields which are also known as the magnetic fluxes (it is the invisible pattern of the magnetism) all around. The strength of the magnetic flux density is always directly proportioned to the amount of the electric currents. Therefore the stronger the magnetic field is caused by, the bigger size of the current. Also when the magnetic field alternate around the piece of the wire. It normally generates the electric current to the wire. Therefore if we put secondary winding next to the primary coil, it automatically induces the current in the secondary wire. The current in the primary winding is known as the primary current, and that in the secondary winding is known as secondary current. The current from the primary coil is induced in the second coil through space, which is known as electromagnetic induction. The current in the primary coil induces magnetic field then magnetic field induces the current in the secondary coil. Electric energy can pass efficiently from primary coil to the secondary coil by wrapping the wire on the soft iron bar or core. The number of the turns on both coils determine the amount of the current that can be produced. It turns on the secondary and primary are the same number, current in primary coil will be the same size to the current to secondary coils, this is same as connecting direct secondary coil with the primary coil. If the secondary coil more turns than the primary coil, there will increase the current produced in the secondary coil. It is the application that is used in the step-up transformers where the current that entered the transformer (primary coil) will be less than currently produced by the transformer (secondary coil). On the other hand, when the secondary coil turns less than the primary coil is turns lead to a decrease of the current produced by the transformer as compared to the current taken in. It is the basic application of the step-down transformers where the current taken by the transformer (primary coil) is more than the current produced by the transformer (secondary coil). This is applied to the induction charger where the current absorbed by the charger from main is more than the size of the current produced by the charger. At some time the charger becomes the worm, because of the difference in the current input and current output. Electric energy produced by the transformer is less than the electric energy feed. Therefore it produces waste heat to equalize the energy difference.
References
Allan, D.J. “Power Transformers – The Second Century.” Power Engineering Journal (1991).
Dalessandro, F. d. S. Cavalcante. “Self-Capacitance of High-Voltage Transformers.” IEEE Transactions on Power Electronics (2007).
Hameyer. “Definition of Transformer Ratio in Section .” (2001).
Khanchandani, M.D. Singh, K.B. Power electronics (2nd ed.). New Delhi: Tata McGraw-Hill, 2008.
Mack, James E., Thomas Shoemaker. “Distribution Transformers.” (2006).
