Demystifying the REF620 Technical Manual: A Guide for Protection Engineers Published: April 18, 2026
Treat it like a dictionary—look up what you need, apply it, and move on. ref620 technical manual
Have a specific REF620 setting you are struggling with? Leave a comment below or check out Hitachi Energy’s online "Technical Note" series for application examples. Demystifying the REF620 Technical Manual: A Guide for
The REF620 Technical Manual is not a bedtime read. It is a reference architecture. Bookmark the Protection Functions chapter, print the Function Block logic gate page for your desk, and keep the Communication section open on a second monitor. The REF620 Technical Manual is not a bedtime read
But let’s be honest: Opening the REF620 Technical Manual for the first time can be intimidating. At nearly 1,000 pages, it is dense. However, once you understand its structure, it becomes the most powerful tool in your toolbox.
If you have worked on feeder protection in a distribution network, you have likely encountered the REF620. As part of ABB’s (now Hitachi Energy) Relion product family, this Intelligent Electronic Device (IED) is a workhorse for overcurrent and arc flash protection.