Relay protection technology has changed over the years, but the underlying operating principles are mostly the same. While many makes and models of relays are used, they generally fall into a handful of categories geared toward a specific purpose. Most relays are used in generation and transmission applications. NERC standards PRC-023-04 and PRC-026-2 direct how each relay is applied.

The Types of Protective Relays training course explains the basic operating principles of common protective relays. It describes how they are used in protection systems. This online training course focuses on:

• Protective relay application
• Relay construction basics
• Instantaneous relays
• Time delay relays
• Directional relays
• Differential relays
• Impedance relays

This course is part of the Elements of System Protection training series.