New IEEE Standard - Superseded. The selection, application, and specification considerations for the unit transformer and unit auxiliaries transformers are described, taking into account their connections, voltage and kilovoltampere ratings, and excitation and through-fault capabilities during possible operating conditions, both normal and abnormal. Consideration is given to direct connections and connections through generator breakers and load-break switches. Both hydroelectric and thermal electric generating stations are covered. Phasing procedures, basic impulse insulation-level selection, and loading practices are not covered.