I'm doing a research on long three phase transmission line protection systems and I found many schemes such as distance protection, merz-price voltage balance system, split-conductor, "translay" protection system, etc.
However, I am not sure protection systems are specific for the number of circuits per transmission lines, that is some circuits work only on single circuit lines other work only double circuit lines.
If there's a difference between the two types of protection systems, is it simply a question of installation, meaning that a protection system is installed on each circuit independently? Or do double circuit transmission lines have their own protection systems?
Thank you!