Difference between Distributor Transformers and Power Transformer

A transformer is an electrical device that changes the level of voltage in a circuit without changing the frequency of the supply. Based on the requirement, this device comes in various models such as auto-transformer, current transformer, power transformer, distribution transformer, dry-type transformer, etc. Transformers work on the principle of electromagnetic induction. Of all the variants, distribution transformers and power transformers are the most widely used. While their overall function remains the same, here are some key differences between the two devices:

Function - Power transformers are used to step up or step down voltage levels for power transmission across long distances. They are usually placed at power generation stations and substations. Distribution transformers are usually placed in power consumption centres in the distribution network. Its main function is to down the voltage levels suited to meet the requirements of the end use which is of lower power voltage. This includes residential areas, commercial spaces, and small industrial settings.

Voltage Leve - In the case of power transformers, the voltage level is considerably higher based on the requirement which can be in the range of thousands of volts. When it comes to distribution transformers, it is usually within the range of a few hundred volts. It is operational in the final stages of power distribution before power is transmitted to end users.

Device Placement - Power transformers are located at power plants and substations where the transmission lines cover long distances across regions. Distribution transformers are located closer to consumer points where the power is distributed between users for their use.

Size - Power transformers are much larger since they have higher capacity ratings which goes to several Mega Volt-Amps (MVA). This is to handle bulk power transfer over long distances which can have an impact on the entire device. In the case of a distribution transformer, it has a smaller size and lower capacity ratings, usually ranging from a few Kilo Volt-Amps (KVA) to a few MVA.

Cooling Mechanism - Power transformers usually come with cooling mechanisms such as oil cooling and forced air cooling depending on the design and application of the device. Smaller transformers like distribution may not require the same level of cooling since they handle lower power levels.

Efficiency and Losses - Power transformers lose energy due to eddy current losses in the core material. Distribution transformers do not have any iron parts making power losses minimal. It loses energy due to hysteresis losses in core material, although they are much lesser compared to power transformers. The efficiency level of power transformers is usually lesser compared to distribution transformers which can go upto 90% efficiency rating.