Friday, March 4, 2011

Accessories of transformer

i. Oil conservator tank

ii. Cooling system

iii. Buch-holz relay

iv. Control panel

v. Drain valve

vi. Bushings

vii. Fan control panel

viii. Top sampling valve

ix. Middle sampling valve

x. Filter valve

xi. Relief valve

xii. Radiator tubes

xiii. ON load tap changer

xiv. Magnetic oil level gauge

Importance of transformer

In our country power generate at l1.5kv. At this voltage current will high and if we transmit power on this voltages line losses will increase because P=I2R. For transmission we use high voltages i.e. 500kv, 220kv, 132kv and 66kv. At these voltages current will low and power losses will also less. For this purpose we use a step up transformer which increase the voltage and decrease the current and at grid station a step down transformer convert again these voltages in 11.5kv. We can’t use these high voltages and the help of step-down transformer we convert voltage as requirement.

Transformers type

I. Step up transformer

Step up transformer increase the given voltage and decrease the current. Its primary winding consists on thick wire and less number of turns but in secondary side thin wire and more number of turn’s w.r.t primary side.

II. Step down transformer

Step down transformer decrease the given voltage and increase the current. Its primary winding consists on thin wire and more number of turns but in secondary side thick wire and less then the number of turn’s w.r.t primary side.


Mutual induction:

The phenomenon in which an alternating current in one coil induces an emf in another coil is called the mutual induction.

Mutual induction of two coils depends upon the following factor:

Ø Number of turns of the coils.

Ø Area of cross-section of the coils.

Ø Closeness of the coils.

Ø Nature of the core material upon which the two coils are wound.


The transformer works on the principle of mutual induction between the two coils. A changing current in the primary winding induces an emf in the secondary winding.


A transformer is an electrical device which is used to increase and decrease given alternating voltage with out any changing in frequency.