DOI link for Power Transformers
Power Transformers book
Power transformers are selected based on the application, with the emphasis toward custom design being more apparent the larger the unit. Power transformers are available for step-up operation, primarily used at the generator and referred to as generator step-up transformers, and for step-down operation, mainly used to feed distribution circuits. In the United States, transformers are rated based on the power output they are capable of delivering continuously at a specified rated voltage and frequency under “usual” operating conditions without exceeding prescribed internal temperature limitations. The normal life expectancy of a power transformer is generally assumed to be about 30 years of service when operated within its rating. The conductors used in power transformers are typically stranded with a rectangular cross section, although some transformers at the lowest ratings may use sheet or foil conductors. Rectangular cores are used for smaller ratings and as auxiliary transformers used within a power transformer.