Difference between Power Transformer and Distribution Transformer


Power Transformer:

Briefly the Power Transformer is a high voltage transformer that is installed at various power stations for generation and transmission of power.  It is a step-up or a step-down transformer that sets voltage criteria to regulate it by increasing or decreasing its level as per the requirement, and it’s also used as an interconnection between two power stations.

Distribution Transformer:

The Distribution Transformer, the younger brother of the power transformer acts to step down the voltage and current level of a transmission line according to the level already set, also called safety level for the end user consumer in domestic and industrial purpose.

Lets read the difference Between Power Transformer and Distribution Transformer:

We have several criteria to study the differences between Power Transformer and Distribution Transformer on the basis of network used, installation settings and whether it is for low or high voltage setting.  Both the transformers have their own design and installation criteria, their current losses and conditions on which they operate, etc.

Briefly these variances are as follows:

Voltage parameters: 

Power transformers are used in high step-up and step down application voltage parameters where the transmission network accepts only higher voltages for different load settings like 400 kV, 200 kV, 110 kV, 66 kV, 33kV, etc. and they and are generally rated above 200MVA.  But distribution transformers have lower voltage distribution networks compatible for end user connectivity. (11kV, 6.6 kV, 3.3 kV, 440V, 230V) and are rated below 200 MVA.


 By structure, a power transformer has just one primary and one secondary setup with one input and output pin whereas a distribution transformer may have a single primary and a “Tapped” secondary, but more than one secondaries, i.e. two or more of them.


The power transformer does enjoy a larger size compared of distribution transformers because of the hefty load it needs to carry without heating its components and keep it cool.

Load resistance: 

Power transformers as the name suggests, are power packed, i.e. they often operate at nearly full load capacity because heavy current utilization is required. However, in a distribution transformer, usually the load is light during the day because it’s works purely for domestic purposes.  So they don’t require hefty current supply.


Power transformers are meant to run for commercial purposes and this reason accounts to their load setting at maximum.  They are designed for maximum efficiency of 100% and since they have to give maximum efficiency, they consume heavy load that assures their full load bearing capacity.  The power of a distribution transformer on the other hand is analyzed by its load bearing efficiency throughout the day as it is designed to serve maximum at 60-70% of load since there is full load only during peak hours of the day and other times, it becomes idle.


Powers transformers indeed have greater electric resonance and their flux density is always higher than that of distribution transformers and so is their magnetic propulsion.  Distribution transformers cannot match this criteria.

Winding methodology: 

There is connectivity difference also in both transformers.  Power transformers have primary winding always connected in star and secondary winding in delta connections while in distribution transformers, the opposite happens.  They have primary winding connected in delta and secondary in star connection.

Metal loss: 

The power transformer incurs copper and iron losses throughout the day because hefty current is passed continuously through the transformer.  But in the distribution transformer, iron losses take place for 24 hours and copper losses are based on load cycle.

Voltage fluctuation: 

Power transformers are there to give constant power supply free of disturbance and value, so they have the least fluctuations, however, since distribution transformers are meant for residential supply mostly, they can have regular load fluctuations.

Thus we see a host of differences between Power Transformer and Distribution Transformer.  Both hold an important place in their usage so their difference is justified on the factors like the type of network used, installation area and high or low voltage output.  The various ratings in which the power and the distribution transformers are available in the market. The designed efficiency and the designing of their core, the types of losses occurring in the transformer, their operating conditions, and various applications have an important identity of the transformer’s efficacious style of working and its efficiency.  Whatever be the reason, both hold to be true power servers to the nation!