Difference Between High, Medium, and Low Voltage Transformers – A step-down voltage transformer reduces a higher level voltage to a lower level. A step-up voltage transformer increases a lower level voltage to a higher level voltage. Thus, the voltage rating of the primary and secondary voltage is very important in deciding the type of transformer.
The voltage transformer has an accurate vector group, voltage transformation, and turns ratio for a particular application. The circuit breaker installed on both the low and high voltage sides of the transformer ensures transformer protection.The voltage transformer is divided into three categories.
- High voltage transformer
- Medium voltage transformer
- Low voltage transformer
High Voltage Transformer
There are three types of voltages
- High voltage
- Extra-high voltage
- Ultra-high voltage
The high voltage transformer is most suitable for transmitting power at a longer distance. These are generally step-up type transformers. The voltage is step up to reduce the line loss. These types of transformers have applications in the laboratory for testing the equipment. The high voltage transformer uses oil for its cooling.
According to American National Standard Institute(ANSI), high voltage transformers can handle a minimum of 115 to a maximum of 1100 Kilovolt.
The medium voltage transformer is most suitable where we need to transmit a substantial amount of power over a long distance. The current is inversely proportional to the voltage and, thus the current reduces. Therefore, the line loss I2R reduces.
According to American National Standard Institute(ANSI), medium voltage transformers can handle 2.4 kV to 69 kilovolts.
Low voltage transformers are suitable for the rectification of AC voltage into DC voltage. These transformers have a limited voltage rating. In this type of transformer, electricity converts by transferring current from one set of electric windings to another.
According to American National Standard Institute(ANSI), low voltage transformers have a minimum capacity of 240 volts and a maximum of 600 volts.
The protection requirement for HV, MV, and low voltage transformers is very important. And, we should select the protection scheme according to electricity rules. For high and medium-voltage transformers special protections like differential protection are a must. The differential protection protects the electrical network in the case of a fault inside of the transformer.
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