This 3D model shows a very basic single phase shell type transformer. This particular 3D transformer is a step-up transformer (more windings on the secondary than on the primary). The design shows the windings mounted on the same limb of the transformer core, but it is also possible to have low voltage windings wrapped around the core limb and the higher voltage windings wrapped around the low voltage windings.
There are two main types of electrical transformer currently used in the market, the shell type, and the core type. The core type transformer is by far the most commonly employed transformer design of the two.
Shell type transformers are often used where a limited amount of space is available. Typical applications include the railway industry, where it is beneficial to lay the transformers on top or underneath the carriages without increasing the overall height of the carriage considerably. Height is a particular concern for trains due to aerodynamic considerations and other considerations such as passing under bridges.
The below video is an extract from our Introduction to Electrical Transformers Online Video Course.