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TYPES OF TRANSFORMERS Chapter-1 Part:-(A) [ Depending upon the type of Construction used ]

Transformers Types
Depending upon the type of Construction used,the transformers are classified into two categories viz,

1) Core type and
2) Shell type

In Core type construction, as shown in fig.
The coil are wound around the two limbs of the a rectangular magnetic core. Each limb carries one half of the primary winding and one half of the secondary windings so as to reduce the leakage reactance to the minimum possible, the LV winding is wound on the inside nearer to the core while the HV winding is wound over the LV winding away from the core in order to reduce the amount of insulation materials required.


Core type Transformers
Core type of Transformer

                    Core type Transformers 

In Shell type Construction, as shown in fig. The coils are wound on the central limb of a three limb core. The entire flux passes through the central limb and decides into two parts going to side limbs. 
Consequently, the x-sectional area ( and hence width ) of the central limb is twice of that of each of side limbs. Sandwich type winding is used in such a construction.


Shell Type Transformer
Shell Type Transformer

                      Shell type Transformer

The present practice is to use core type Transformers in large high voltage installations. The shell type construction is commonly used for small Transformers where a square or rectangular core X-sectional is suitable for economic Considerations.

Power Transformers 

The terms is used to include all Transformers of large size ( 250 KVA and above ) used in generating station and substation for Transforming  the voltage
At each end of a power transmission line. They may be single phase or 3- phase ; 3-wire  Delta/Delta or Delta/star connected; and of Voltage rating 220/11 KVA or in high voltage range. They are put in operation during load hours i.e., the are usually operated on approximately full load. This is possible because they are arranged in banks and can be thrown in parallel with other units or disconnected at will. They may be self oil cooled, forced air cooled or forced water cooled.

Distribution Transformers

Transformers of rating up to 200 KVA, used to step down the distribution voltage to a standard service voltage are known as Distribution Transformers. They are kept in operation all the 24 hours a day whether they are carrying any load or not. 
They are of the self cooling type and are almost invariably oil-immersed.

Here is more basic knowledge of Transformer so click here [ Basic Transformers ]


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