GE L60, Instruction Manual, Page: 258 / 498

5-166 L60 Line Phase Comparison Relay GE Multilin
5.6 CONTROL ELEMENTS 5 SETTINGS
5
• TRIP PILOT PRIORITY : This setting is used to set an interval equal to the inter-relay channel communications time,
plus an appropriate margin, during which outputs are not asserted. This delay permits fault identification information
from a remote terminal to be used instead of local data only.
• REVERSE FAULT : This setting should be used to guarantee accuracy of single-pole tripping under evolving external to
internal faults. When a close-in external fault occurs, the relay is biased toward very fast operation on a following inter-
nal fault. This is primarily due to depressed voltages and elevated currents in response to the first, external fault. The
phase selector may exhibit some time lag compared to the main protection elements. This may potentially result in a
spurious three-pole operation on a single-line-to-ground internal fault. Delaying tripping on internal faults that follow
detection of reverse faults solves the problem.
As long as the operand indicated under this setting is asserted the trip action will be delayed by
TRIP DELAY ON EVOLV
FAULTS
time. Typically this operand should combine reverse zone indications (such as Zone 4 pickup) with a half-cycle
pickup delay, and 2-cycle dropout delay. This setting should be used only in single-pole tripping applications, when
evolving faults are of importance, and slightly delayed operation on evolving faults could be traded for enhanced accu-
racy of single-pole tripping.
• TRIP DELAY ON EVOLV FAULTS : This setting should be used in conjunction with the
REVERSE FAULT
setting (see
above). Typically this value should be set around half a power system cycle. This setting should be used only in single-
pole tripping applications, when evolving faults are of importance, and slightly delayed operation on evolving faults
could be traded for enhanced accuracy of single-pole tripping.