Step up and Step down Transformer
This type of transformer is categorized on the basis of a number of turns in the primary and secondary windings and the induced emf.
The power transformers are used in the transmission networks of higher voltages. The ratings of the power transformer are as follows 400 KV, 200 KV, 110 KV, 66 KV, 33 KV. They are mainly rated above 200 MVA. Mainly installed at the generating stations and transmission substations. They are designed for maximum efficiency of 100%. They are larger in size as compared to distribution transformer.
This type of transformer has lower ratings like 11 KV, 6.6 KV, 3.3 KV, 440 V and 230 V. They are rated less than 200 MVA and used in the distribution network to provide voltage transformation in the power system by stepping down the voltage level where the electrical energy is distributed and utilized at the consumer end. The primary coil of the distribution transformer is wound by enamel coated copper or aluminum wire. A thick ribbon of aluminum and copper is used to make secondary of the transformer which is high current, low voltage winding. Resin impregnated paper and oil is used for the insulation purpose.
The current transformer is used for measuring and also for the protection. When the current in the circuit is high to apply directly to the measuring instrument, the current transformer is used to transform the high current into the desired value of the current required in the circuit.
The potential transformer is also called as the voltage transformer. The primary winding is connected across the High voltage line whose voltage is to be measured, and all the measuring instruments and meters are connected to the secondary side of the transformer. The main function of the Potential transformer is to step down the voltage level to a safe limit or value. The primary winding of the potential transformer is earthed or grounded as a safety point.
Single Phase Transformer
A single phase Transformer is a static device, works on the principle of Faraday’s law of mutual Induction. At a constant level of frequency and variation of voltage level, the transformer transfers AC power from one circuit to the other circuit. There are two types of windings in the transformer. The winding to which AC supply is given is termed as Primary winding and in the secondary winding, the load is connected.
Three Phase Transformer
If the three single phase transformer is taken and connected together with their all the three primary winding connected to each other as one and all the three secondary windings to each other, forming as one secondary winding, the transformer is said to behave as three phase transformer, that means a bank of three single phase transformer connected together which acts as a three-phase transformer.