How to Test Relays ep2: Purpose, Types, & Applications of Protection Relays

Gentlemen welcome back! Today we're taking a look at the major types, vintages, and applications of protection relays, as well as the basic building blocks of circuit protection as power systems have evolved over the last 100+ years.

Useful Links:
My video on low voltage circuit breaker testing (Thermal Curve Explanation)
   • How to Test Breakers ep1: Thermal Mag...  

Another very good video about thermal/magnetic circuit breakers by @EngineeringMindset
   • Why Circuit Breakers DON'T Protect Pe...  

An explanation of Current Transformers (CTs) by Eaton
   • Current Transformers (CT)  

Getting started with phasor diagrams by @ScienceAsylum
   • What the HECK is a Phasor? Alternatin...  

0:00 Intro
0:36 Basics of Circuit Protection
6:36 Example Substation Control Schematic
7:42 Electro-mechanical Relays
9:55 Solid State / Static Relays
11:33 Modern Microprocessor Relays
12:46 Undervoltage Relay Applications
13:15 Directional Power Applications
14:42 Distance Protections Applications
15:45 Differential Relay Schemes
17:50 Purpose of Relay Testing