The simple definition on an auto transformer is that it is an electrical transformer which has only one winding. An auto transformer is basically used in situations where at times when the voltage actually reaches a peak level and it gets dangerous .In such a situation the auto transformer is the best choice. Designing this type of transformer is not a very difficult task as such, you just need to do very small modifications in the normal Autotransformer to get the desired result. The auto transformer is very conveniently and efficiently used basically to step up or step down the ac mains whenever it is required and this can thus be done manually.
Some insight
An auto transformer basically consists of few single windings, which is placed over the iron core and this basically has a single input but on the other hand it thus has multiple outputs. All these outputs can then be actually arranged in steps and thus you can start from the voltage less as compared with the input AC mains voltage and hence on the other side ending is basically done with voltages which are definitely higher that the input voltages. In this auto transformer it is certainly possible to actually vary the output voltage which can definitely be done starting from zero and can then reach much higher voltages as when you compare them with the input supply voltage.
Principal of working
The principal on which the auto transformer works is quiet simple and its working is very easy to understand at a basic level. This particular transformer has many inherent properties and due to which it develops the instantaneous polarity for the current which generally flows only via the primary winding as such and this current has to be definitely opposite, by normal principle current of the secondary winding at any cost come what may for the transformer to work efficiently and effectively. And by normal principles it so happens that the secondary voltage actually gets deduced basically from only one source which is the applied input voltage as such. And when you join all the similar ends , in normal circumstances you observe that the magnitude of the secondary voltage basically gets added to all the input main voltages and this happens because of the true fact that the current in both the windings is in the same direction.
The auto transformer ultimately has many features and that is the main reason for making this particular transformer so popular. Some of its features are it is anti abrasion and anti corrosion, the maintenance of this transformer is very simple and it is very easy to install as such, it takes very less time for its installation, it saves a lot of energy and also by using this particular transformer you also land up in consuming lot of energy and so your electricity bill will be considerably reduced, it has an excellent sturdy build with an excellent voltage regulation. Hence auto transformer is very efficient.
