Protection Engineering Basics and Schemes Protection Engineering | Page 118
t =
13. 5 TMS I − 1
5.3.2.3 Extreme Inverse TCC Relay:
Mostly employed at generating stations, where fault current is moderately higher then transmission and distribution systems, also recommended for motors where initially time delays are introduced but after time delay if current remain high motor could be damage, so to minimize chances of damage extreme inverse TCC relay is used for motor t = 80TMS I 2 − 1
5.3.2.4: Long time standing Earth fault TCC Relay:
This employees mostly as back up earth fault protection, relay with this characteristics ensure operation when all earth fault protection fails.