Electrical transformers can be classified into different categories depending upon their end-use, construction, supply, and purpose.
On the Basis of Design
- Core Type Transformer This transformer features two horizontal sections with two vertical limbs and a rectangular core with a magnetic circuit. Cylindrical coils (HV and LV) are placed on the central limb of the core type transformer.
- Shell Type TransformerThe shell type transformer has a double magnetic circuit and a central limb with two outer limbs.
On the Basis of Supply
- Single Phase TransformerA single-phase transformer has only one set of windings. Separate single-phase units can offer the same results as three-phase transfers when they are externally interconnected.
- Three Phase TransformerA triple-phase (or three-phase) transformer has three sets of primary and secondary windings to form a bank of three single phase transformers. The three phase transformer is mainly used for generation, transmission and distribution of power in industries.
On the Basis of Purpose
Step Up Transformer
This type is determined by the number of turns of wire. So, if the secondary set has a greater number of turns than the primary side, it means that the voltage will correspond to that, which forms the base of a step up transformer.
Step Down Transformer
This type is typically used for stepping down the level of voltage in the power transmission and distribution network and so its mechanism is the exact opposite of a step up transformer.
These transformers are used to relay and protect instruments simultaneously.
On the Basis of Cooling
- Self-Cooled Oil-Filled TransformersThis type is generally employed in small transformers of up to 3 MVA and is it designed to cool itself by the surrounding air flow.
- Water-Cooled Oil-Filled TransformersThis type of electrical transformer employs a heat exchanger to facilitate the transfer of the heat from the oil to the cooling water.
- Air-Cooled (Air Blast) TransformersIn this type of transformer, the heat that is generated is cooled with the help of blowers and fans that force the circulation of air on the windings and the core.