Main parts of Transformer

Oil conservator

It is a drum shaped cylindrical vessel mounted on the top of the transformer.  it is connected to a pipe to the transformer tank containing oil.  the oil expands and contracts to depend upon the heat produced and the oil level in the conservator rises and fails. so, it maintains the oil level in the transformer main tank.


Breather is a box containing calcium chloride or silica gel to absorve moisture of air entering the conservator, when oil level in the conservator changes, air moves in or out of the conservator. This process is called breathing. so, breather confirms that dry air enters the transformer. colour of silica gel is blue when dry. its colour changes to pink absorbing moisture.


It is a gas actuated relay which is used for protection of oil immersed or oil fill transformer or insulation failure, core heating of any type of internal fault which may cause the heating of oil beyond the specified temperature. due to an internal fault, oil is heated and oil vapor so formed causes either the alarm circuit or trip circuit to function.

Temperature indicator

It is a protective device fitted to a transformer to indicate the temperature of transformer oil and winding.  alarm contacts are provided when temperature exceeds a predetermined maximum temperature under abnormal condition.

Explosion Vent

It is a safety device of a transformer which protects the transformer tank from gases induced by any type of short circuit in the transformer.


The bushing solves as supports an insulation of the bus bar and transformer terminals. the winding of a transformer is connected to the lines through the copper rods, which are insulated from the tank cover, this structure is known as bushing.

Magnetic oil gauge

The magnetic oil gauge supervised the level of oil in the conservator tank. The oil level gauge is provided on the transformers is another dial type with minimum and maximum level marking. The movement of float arm the switch mechanism by means of magnetic coupling. The pointer is also magnetically coupled.

Tap changing

The voltage control of transmission and distribution system is obtained by tap changing. Tap changers are either On- Load or Off-Load tap changer. Tap changer is fitted with the transformer for adjusting the secondary voltage. The voltage control of the range +-16% can be achieved by tap-changing transformer.

Cooling equipment

The radiators cooling fans are provided for cooling of transformer. Oil circulating pump is provided for cooling of transformer internal parts.

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