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 guide covers tests to help ensure correct connections of differential relays and polarizing circuits of phase and ground relays. Although other preparatory tests are mentioned in this guide, these tests are not discussed in detail.

This guide provides a methodology to establish a systematic series of tests to verify the integrity and accuracy of connections of differential and polarizing circuits.