14-11-2012, 11:52 AM
STUDY OF TRANS FORMER AN INDUCTOR
STUDY OF TRANS FORMER AN INDUCTOR.pptx (Size: 98.1 KB / Downloads: 35)
Transformer
Transformer is a static (without any rotation part) piece of apparatus which transforms electric power (Only AC, not DC) from one circuit to another circuit without any change in frequency. It does so with a change in voltage and current. It works in the principle of mutual induction of two inductive coils (copper windings or coils) linked with a low reluctance path (steel core). The power is transformed entirely magnetically.It is of two types.
WORKING
A transformer is a device which is use to convert high alternatic voltage to a low alternatic voltage and vice versa.
WORKING PRINCIPLE
Transformer works on the principle of mutual induction of two coils. When current in the primary coil is changed the flux linked to the secondary coil also changes. Consequently an EMF is induced in the secondary coil.
CONSTRUCTION
A transformer consists of a rectangular core of soft iron in the form of sheets insulated from one another. Two separate coils of insulated wires, a primary coil and a secondary coil are wound on the core. These coils are well insulated from one another and from the core. The coil on the input side is called Primary coil and the coil on the output side is called Secondary coil.
WORKING
Suppose an alternatic voltage source Vp is connected to primary coil. Current in primary will produce magnetic flux which is linked to secondary. When current in primary changes, flux in secondary also changes which results an EMF Vs in secondary. According to Faradays law EMF induced in a coil depends upon the rate of change of magnetic flux in the coil. If resistance of the coil is small then the induced EMF will be equal to voltage applied.
APPLICATION AND USES
Transformers can be used to transform impedance as well as voltage and current. When this is done to improve power transfer to a load, it is called impedance matching. A Potential Transformer (PT) is a special instrument transformer designed to provide a precise voltage step-down ratio for voltmeters measuring high power system voltages. A Current Transformer (CT) is another special instrument transformer designed to step down the current through a power line to a safe level for an ammeter to measure. An air-core transformer is one lacking a ferromagnetic core. A Tesla Coil is a resonant, air-core, step-up transformer designed to produce very high AC voltages at high frequency. A saturable reactor is a special type of inductor, the inductance of which can be controlled by the DC current through a second winding around the same core. With enough DC current, the magnetic core can be saturated, decreasing the inductance of the power winding in a controlled fashion. A Scott-T transformer converts 3-φ power to 2-φ power and vice versa. A linear variable differential transformer, also known as an LVDT, is a distance measuring device. It has a movable ferromagnetic core to vary the coupling between the excited primary and a pair of secondaries.