Based on standard three-phase voltage output, it features six independent, high-precision, high-power current output channels, specifically designed for verifying and testing large and complex protection systems (such as generator-transformer unit differential. Based on standard three-phase voltage output, it features six independent, high-precision, high-power current output channels, specifically designed for verifying and testing large and complex protection systems (such as generator-transformer unit differential. From the practical requirements of on-site electrical testing, this article will deeply analyze the core technical metrics you must focus on when purchasing a protection relay test set, and teach you how to evaluate the fundamental capabilities of original manufacturers. Voltage and Current. TEST-630 protection relay tester is a relay test equipment which offers all the characteristics and functions needed for protective relay testing, in a manual or automatic mode, designed for using on site or in the laboratory. It uses the latest generation of. The CMC 356 is the universal solution for testing all generations and types of protection relays.