Distribution Transformers: Selection And Placement
Distribution transformers are used both within electrical power distribution and transmission systems. The power rating of a transformer is generally determined through the cooling method and the coolant used. Oil or a few such other heats conducting material is commonly used as coolant. Ampere rating is increased in a distribution transformer through increasing the size of the primary and secondary windings; voltage ratings are increased through increasing the voltage rating of the insulation used in making the transformer.
The criteria for selection of a transformer and its technological details depend on its intended use or reasons, working conditions and operating requirements. For instance, a power transformer is selected within the sub-transmission level since it is consistently loaded up to full rating in order to acquire maximum efficiency at full load. Instead, distribution transformers (in the power distribution system) are under-loaded most of the time in order to ensure maximum all day efficiency at the expense of lower efficiency during peak hours. In sequence to understand these criteria, you required to know about transformer classification.