# Types of transformers

In the previous post about energy, I talked about how transformers work. In this post I will talk about many types of transformers. Click in the following button to know how the transformers work.

Single phase transformers

In electrical engineering phase means voltage signal, when something is single phase it means that operates with one voltage signal. Exist low power single phase transformers used by hobbists and DC sources.

And exist these high power mono phase transformers used in substations.

Three phase transformers

As the the name says, has three voltage signals. Most of transformers in power systems are three phase.

Coils of lower voltage are connected in delta configuration and of higher voltage are connected in star configuration. Delta configuration is in the triangle form and the star is in form of “Y”.

Autotransformers

In an autotransformer, it have the same winding to primary and secondary. While the higher voltage winding is the entire coil, the lower voltage winding get a part of the coil. In the left we have a step down autotransformer and in the right the step up.

The relation transformation equation, being that $N_{1}$ and $N_{2}$ are the spires of primary and secondary respectively.

$r_{t}=\frac{N_{1}}{N_{2}}$

Autotransformers are cheaper, lighter, smaller, has a higher efficiency and lower voltage drop. However there is no electrical insulation. Are used in reduction of electrical energy distribution and deal with lower voltage than in other types of transformers.

Current transformers

Reduce the current level to detect and measure it with an instrument.

Current transformers to measure.

High voltage current transformers.

Winding types

High power transformers receive high current, the transformer’s wires needs a big section area, for that it is common transformers have 2 or more wires in parallel to reduce loses by parasitic current.

In addition to the spiral winding, exist others ways to wrap transformer’s wires. One of the ways is the cross-over, to high power and currents above 20A, consist in make spiral blocks and let space between the blocks. The space serve to decrease the heating.

The type disc winding is another cross-over winding, however it uses conductor in tape shape.

In the sandwich winding, higher and lower voltage block are alternated.