Protection Engineering Basics and Schemes Protection Engineering | Page 130

When generation is fixed and fault current is large or
small due to line and location then inverse time
characteristics in relay used, but with fluctuated
generation the definite time relay characteristics is used.
In this relay basically three tap settings are given.
Lower starts from 0.5 to 2.5 Amperes (ground faults)
Medium (2-6A) and high (4-12A) is for high value of fault
current.
Example:
In it when fault occur at M, the relay with 0.35sec will
operate before 0.85 TMS relay and isolate the faulty
section from circuit.
pg. 130