Types of Transformer
Transformers can be categorized in different ways, depending upon their purpose, use, construction etc. The types of transformer are as follows,
- Step Up Transformer and Step Down Transformer – Generally used for stepping up and down the voltage level of power in transmission and distribution power system network.
2. Three Phase Transformer and Single Phase Transformer – Former is generally used in three phase power system as it is cost effective than later. But when size matters, it is preferable to use a bank of three single phase transformer as it is easier to transport than one single three phase transformer unit.
3. Electrical Power Transformer, Distribution Transformer and Instrument Transformer – Power transformers are generally used in transmission network for stepping up or down the voltage level. It operates mainly during high or peak loads and has maximum efficiency at or near full load. Distribution transformer steps down the voltage for distribution purpose to domestic or commercial users. It has good voltage regulation and operates 24 hrs a day with maximum efficiency at 50% of full load. Instrument transformers include C.T and P.T which are used to reduce high voltages and current to lesser values which can be measured by conventional instruments.
4.Two Winding Transformer and Auto Transformer – Former is generally used where ratio between high voltage and low voltage is greater than . It is cost effective to use later where the ratio between high voltage and low voltage is less than 2.
5. Outdoor Transformer and Indoor Transformer – Transformers that are designed for installing at outdoor are outdoor transformers and transformers designed for installing at indoor are indoor transformers.
6. Oil Cooled and Dry Type Transformer – In oil cooled transformer the cooling medium is transformer oil whereas the dry type transformer is air cooled.
7. Core type, Shell type and Berry type transformer – In core type transformer it has two vertical legs or limbs with two horizontal sections named yoke. Core is rectangular in shape with a common magnetic circuit. Cylindrical coils (HV and LV) are placed on both the limbs.
Shell type transformer: It has a central limb and two outer limbs. Both HV, LV coils are placed on the central limb. Double magnetic circuit is present.
Berry type transformer: The core looks like spokes of wheels. Tightly fitted metal sheet tanks are used for housing this type of transformer with transformer oil filled inside.