Traveling Wave Relays

[thermionic1]

We have a project coming up where the client is using the new SEL T-400 traveling wave relay. I've read a bit about it and am curious if anyone else has applied it or similar to Transmission Line Protection.

 

[JG2828]

They have been around since 2015 and they are fairly expensive with a published list price of $12,000 each. You need one at each end of the line, similar to line current differential. Unfortunately I have not had a chance to use them on any projects yet.