The issues concerning testing and verification of the correctness of differential and polarizing circuits are described and discussed in this guide. The intention of this guide is to help the reader to detect errors in the wiring of protective relays that might cause erroneous operations of protection systems. It is essential to follow systematic testing procedures and record the observations in a proper organized manner. The records should include documentation of all measurements and a comparison with the desired results

This project will review and summarize as well as update the testing specified in the 1990 Guide for Testing of Differential and Polarizing Relay Circuit Testing. This project will be limited to proven, in use test being conducted at the present time by users.

This revised guide will serve as a reference for all users whether utility, industrial or contractors, to choose the most accurate and efficient method of testing using the resources available to ensure correct connections and therefore correct operators.