Importance of Variable Auto Transformer In Power Supply


Are you looking for an easy and efficient way to reduce the cost of conventional transformers? If yes, then autotransformer can be the most suitable option for you as it plays a crucial role in the power supply. So let’s have a look at this important device that can turn your electricity needs easier anytime and anywhere.


An Auto Transformer can be defined as a one winding transformer which is wounded on a laminated core. Both the primary and secondary sides have a small portion of common winding, which is not so in the case of an ordinary transformer in which they are not connected.  In an autotransformer, the transformer turns ratio equal to the ratio of secondary to the primary voltage. Various devices operating at different voltage can be connected through autotransformer. They can also be used to operate a low voltage device on a high voltage and vice versa.

Applications and usage of variable autotransformers

Variable autotransformers are one of the essential components of the power supply chain. They are used when the voltage has been changed regularly across the lines for the power to be supplied to households. In case of long power distribution lines, they act as voltage regulators so that household users get consistent average supply. They are also used to interconnect parts or components which are functioning at different voltages. An autotransformer is commonly used as a voltage regulator and even converts voltage for using on different devices. Using an autotransformer makes sure that a device built to operate on a particular voltage, for example, a device meant for low voltage can function on high voltage as well. These are also the points of common linkage between voltages in a household grid. Thus all these uses make variable autotransformers an indispensable part in power transmission and distribution system. High voltage Autotransformers are commonly used in transmission and distribution of power because of their cheap and simple designs as compared to the power transformers

Variable autotransformers provide variable AC supply from a constant AC source. Popularly known as variac, it is commonly used in schools and colleges. Apart from this, they’re commonly used for matching impedance in an audio system where they attach speakers to a regulated supply of voltage. They are widely used in railways where the transformer links supply chain and railway wire. Lastly, they’re commonly applied to starting induction motors.


Variable autotransformers should be made only with superior quality copper. Using good quality material ensure that our transformers have a comparatively lower loss and drop of voltage. A transformer ratio meter to calculate the ratio and other errors in various phases of transformers. It is a fully automatic procedure, thus removing any scope of human error in calculations and making it highly convenient.

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