scope:

This guide describes selection and application considerations for the unit power transformer and unit auxiliary power transformer. Consideration is given to connections that include direct connection and connections through generator circuit breakers and load-break switches. The considerations referred to in this guide apply to hydroelectric and thermal electric generating stations. Various power transformer connections and possible operating problems under normal and abnormal conditions are treated. Phasing procedures, basic impulse insulation level selection, and loading practices are not covered.

Purpose

The terminology, function, application, theory of operation and protection, and design of unit power transformers and unit auxiliary power transformers are not covered by existing transformer standards and guides. The purpose of this document is to provide guidance for specifying, designing, and applying these types of power transformers.