Custom Built Auto Transformer
General Purpose transformer may be banked to achieve a variety of three phase voltage combination.
In any auto transformer portions of same wounding act as both primary and secondary sides of transformer. In contrast an ordinary transformer has separate primary and secondary wounding that are not electrically connected.
An auto transformer is often used to step up and step down the voltage level. This allows all European equipment’s to fed from higher European voltages.
In general type transformer Magnetic are built with 220/380/440/480 V for middle East countries. In such cases if the main supply is 480 V and the equipment is 220 V There the auto transformer can be used tho step down the voltage or vice versa.
LIMITATION OF AUTO TRANSFORMER:
Auto transformer do not provide electrical isolation between its winding. If the neutral side of the input voltage is no at ground voltage neutral side of output will not be either. A failure of winding in an auto transformer results in full input voltage being applied to output.This is an important safety consideration when deciding to use an auto transformer in an given application