Because of the important role that power transformers play in their high cost and the characteristics involved in the design, transportation, assembly, energization, operation and protection phases, it is very important that the professionals involved in any of these stages are trained and that the characteristics of the equipment they are dealing with. It is very important to be able to identify the windings of the power transformers, since an incorrect connection can cause a lot of damage and damage. A very common transformer model found in most appliances is a transformer that uses wires to make electrical connections, both primary and secondary.
In relation to the primary we usually find two categories, the three-wire models made from a single primary and the four-wire primary, made from two primaries. In order to be able to use the transformer according to the local voltage we need a device that can do the switching, ie switching to 110V (127V) or for use in 220V, this switching is likely using an HH switch.
To better understand the application of the transformers, it will be necessary to check the rectification, filtering and regulation circuits, as providing correct voltage for these circuits is the main function of the transformer.