ABSTRACT
The transformer is a valuable apparatus in electrical power systems, for it enables us to utilize different voltage levels across the system for the most economical value. Generation of power at the synchronous machine level is normally at a relatively low voltage, typically 20 kV, which is most desirable economically. Stepping up of this generated voltage to high voltage, extra-high voltage, or even to ultra-high voltage is done through power transformers to suit the power transmission requirement to minimize losses and increase the transmission capacity of the lines. This transmission voltage level, typically ranging from 115 to 750 kV, is then stepped down in many stages for distribution and utilization purposes in the range of 115/230 v for home use to 13,200 v in large industrial equipment. The Tap Changing under Load transformer maintains a prescribed voltage at a point in the system by changing the transformation ratio by increasing or decreasing the number of active turns.
