The application, installation, operation, and maintenance of single- and polyphase dry-type general purpose, distribution, power, and autotransformers are covered. The following types are included: ventilated, indoor and outdoor, self- or forced-air cooled; nonventilated, indoor and outdoor, self- or forced-air cooled; and sealed, indoor and outdoor, self-cooled. Instrument transformers, step voltage and induction-voltage regulators, arc furnace transformers, rectifier transformers, and specialty transformers are not covered.

1.1 Transformers Covered This recommended practice covers general recommendations for the application, installation, operation and maintenance of single and polyphase dry-type general purpose, distribution, power, and auto-transformers of the following types: 1) Ventilated, indoor and outdoor, self-cooled cooled or forced air cooled 2) Nonventilated, indoor and outdoor, self-cooled or forced air cooled 3) Sealed, indoor and outdoor, self-cooled 1.2 Transformers Not Covered This recommended practice does not apply to the following: 1) Instrument transformers 2) Step voltage and induction voltage regulators 3) Arc furnace transformers 4) Rectifier transformers...

This recommended practice is intended for general use in the application, installation, operation, and maintenance of dry-type transformers manufactured in accordance with ANSI/IEEE C57.12.01-1979 [10]1, ANSI C57.12.50-1980 [2], ANSI C57.12.51-1981 [3], ANSI C57.12.52-1981 [4] and ANSI/NEMA ST 20-1972 [13]. Familiarity with other American National Standards applying to dry-type transformers and to their protection is assumed and the provisions of those standards are indicated herein only for clarity.