Protection methods for different types of phase shifting transformers (PST) are provided in this guide, and the interaction between protection and operating conditions of PSTs is discussed. Models representing PSTs to determine short circuit currents for relaying functions are presented. Sizing and location issues of protection current transformers employed in the protection of PSTs are included. Examples of appropriate relay applications and settings are provided.

This guide provides protection methods for different types of phase shifting transformers (PSTs) and discusses the interaction between protection and operating conditions of PSTs. Models representing PSTs to determine short circuit currents for relaying functions are presented. Sizing and location issues of protection current transformers employed in the protection of PSTs are included. This guide provides examples of appropriate relay applications and settings.

The purpose of this guide is to provide protection engineers with information that helps them to properly apply relays and otherre devices to protect phase-shifting transformers.