ABSTRACT
Shell-type transformers were developed for very-high-magnitude short-circuit applications such as generator step-up transformers. Taps are provided on a transformer to be able to adjust the voltage ratio of the transformer. These taps are provided along the winding with connections to a tap-changing device that makes the physical change in the in-service tap. The main parts of a transformer are: iron core, magnetic circuit; high-voltage and low-voltage, or multiple secondary, windings; and a tank for liquid-immersed transformers and an enclosure for dry-type transformers. The basic core and coil configurations are: core type and shell type. Transformer windings are manufactured of copper or aluminum, although the majority of users specify copper. In liquid-filled transformers, the winding terminals are brought out through bushings for connection to bare conductors or insulated power cable. The transformer loading can be increased for lower ambient temperatures and decreased for higher ambient temperatures, without sacrificing the life expectancy of the transformer.
