Main Difference between Power Transformer and Distribution Transformer
In brief, those transformers installed at the ending or receiving point of long and high voltage transmission lines are the power transformers (mostly Step up). At the other hand, The distribution transformers (generally pole mounted) are those installed nearby the load terminals (City and villages) to provide utilization voltage at the consumer terminals (mostly step down).
Below are some additional differences between power and distribution transformers.
- Power transformers are used in transmission network of higher voltages for step-up and step down application (400 kV, 200 kV, 110 kV, 66 kV, 33kV) and are generally rated above 200MVA.
- Distribution transformers are used for lower voltage distribution networks as a means to end user connectivity. (11kV, 6.6 kV, 3.3 kV, 440V, 230V) and are generally rated less than 200 MVA.
- A power transformer usually has one primary and one secondary as well as one input and output setup. A distribution transformer may have one primary and one divided or “Tapped” secondary, or two or more secondaries.
- Power transformers generally operate at nearly full – load. However, a distribution transformer operates at light loads during major parts of the day.
- The performance of the power transformers is generally analyzed by commercial or maximum efficiency because they are designed for maximum efficiency at full load. Whereas, the performance of a distribution transformer is judged by all day efficiency of transformer because they are designed to be operated for maximum efficiency at 60-70% load as they are normally doesn’t operate at full load all the day as there are peak hours for load in 24 hrs which are not same at once all the time.
- The rating of a high transformer is many times greater than that of distribution transformer.
- In Power Transformer, the flux density is higher than the distribution transformer.
- Power transformers, primary winding always connected in star and secondary winding in delta connections while in distribution transformers, primary winding connected in delta and secondary in star connection. read more about the comparison between star & delta connections.
- In The Sub station, at the end of the transmission line, The power transformer connection is in Star-Delta.(to step down the level of voltage)
- At the beginning of the transmission line (H-T), the connection of the power Transformer is in Delta – Star (to step up the level of voltage). Also, not that the same connection i.e Delta – Star connection is used in three phase step down distribution transformer as well