Electrical Engineering Home

Constructionally, the transformers are of two general types, distinguished from each other merely by the manner in which the primary and secondary coils are placed around the laminated core. The two types are:- Core type   Shell type Another recent development is spiral core or wound core type, the trade name being spirakore transformer. Core type transformer:- In the core type transformer, the windings surround a considerable part of the core. In the simplified diagram of the core type transformer, the primary and secondary winding are shown located on the opposite limbs of the core, but in actual construction they are interleaved to reduce leakage flux. As in the figure, half the primary and half the secondary winding have been placed side by side or concentrically on each limb, not primary on one limb and the secondary on the other. The coil used are form-wound and are of the cylindrical type. In small size core type transformers, a simple rectangular c...

The transformers are not connected on dc and never connected to a dc source. There will be no self emf in the primary when the transformer are connected to a dc supply. If a rated dc voltage is applied to the primary of a transformer, the flux produced in the transformer core will not vary but remain constant in magnitude and therefore no emf will be induced in the secondary winding except at the moment of switching on. Since the resistance of the primary winding is low, therefore a heavy current will flow through the Primary winding which may result in the burning out of the primary winding. This is reason that dc is never applied to a transformer. Subscribe, share and leave your comments in the comment box below. Thank you :)

An elementary transformer consists of soft iron core and two windings placed on it. The core is built up of thin soft iron or silicon steel laminations to provide low reluctance to the magnetic flux. Working: When the primary winding is connected to an ac supply mains, a current flows through it. Since, the winding links with an iron core, so current flowing through this winding produces as alternating flux in the core. This alternating flux links with the secondary winding. Due to Electromagnetic Induction, emf gets induced in the secondary winding. The induced emf in the secondary winding enables it to deliver current to an external load connected across it. Thus, energy is transferred from primary to secondary winding by means of Electomagnetic induction without any change in frequency.  

The transformer basically consists of two coils having mutual inductance and laminated steel core. The coils are insulated from each other and the steel core. Other necessary parts are: Some suitable container for assembled core and windings. a suitable medium for insulating the core and windings from the container. suitable bushings for insulating and bringing out the terminals of windings from the tank. In all types of transformers the core is constructed of steel sheet laminations assembled to provide a continuous magnetic path with a minimum of air gap included. The steel used is of high silicon content. The eddy current loss is minimized by laminating the core. The thickness of the laminations varies from 0.35mm for a frequency of 50 Hz to 0.5mm for a frequency of 25 Hz. The sheets are imbricated to avoid the narrow gaps through the cross section of the core. Types of Transformers On the basis of construction, transformers are of two types: 1. Core T...

Learning Objectives 1. Working Principle of Transformer 2. Construction Details 3. EMF Equation of Transformer 4. Voltage Transformation Ratio 5. Losses in Transformer 6. No Load and on load operation 7. Testing of Transformation 8. Efficiency and Voltage Regulation 9. Kapp Regulation Diagram 10. Auto Transformer 11. Instrumental Transformer (C.T and P.T)