The scope of this guide includes general philosophy, practical applications, and economic considerations
involved in power transformer protection.
Emphasis is placed on practical applications. General philosophy and economic considerations in
protecting transformers are reviewed. Types of faults in transformers are described. Technical problems
with the protection systems, including the behavior of current transformers (CTs) during system faults, are
discussed. Associated problems, such as fault clearing and reenergization, are discussed as well.