GE D90 Plus - Page 359

CHAPTER 7: PROTECTION CONTROL ELEMENTS
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 349
Zone 1 extension in the autoreclose scheme
Two approaches are available for implementation of zone 1 extension. The first method is
to operate normally from an under-reaching zone and use an overreaching distance zone
when reclosing the line with the other line end open. This method can be programmed via
the line pickup scheme.
A second method applies an over-reaching zone as long as the relay is ready to reclose,
then blocks this zone when reclosing. The autoreclose scheme provides an AR ZONE 1
EXTEND operand that can be used to supervise the over-reaching zone or change to a
setting group where zone 1 is over-reaching.
The AR ZONE 1 EXTEND operand is set to logic 0 when autoreclose is in lockout or disabled
and logic 1 when autoreclose is in reset. When extended zone 1 operand is logic 0, set the
distance functions to the normal under-reach zone 1 setting. When extended zone 1
operand is logic 1, the distance functions can be set to the extended zone 1 reach. During
a reclose cycle, the AR ZONE 1 EXTEND operand goes to logic 0 as soon as the first CLOSE
BREAKER signal is issued (AR SHOT COUNT > 0 operand) and remains at 0 until the recloser
returns to reset.
Figure 292: Autoreclose zone 1 extension logic
Force three-pole tripping
The reclosing scheme contains logic that is used to signal trip logic that three-pole tripping
is required for certain conditions. This signal is activated by any of the following conditions:
• The autoreclose scheme is paused after it was initiated
• The autoreclose scheme is paused
• The autoreclose scheme is in the lockout state
• The autoreclose mode is programmed for three-pole operation
• The shot counter is not at 0; that is, the scheme is not in the reset state. This ensures a
second trip is three-pole when reclosing onto a permanent single phase fault.
• 1.25 cycles after the single-pole reclose is initiated by the AR 1P INIT signal
Figure 293: Autoreclose force three-pole trip logic
Terminal manual close
The manual close logic receives the manual close signal from each of the breakers and
derives a manual close signal for the local terminal. The manual close is declared when
• Breaker 1 issues a manual close signal, sequence 2 is not selected, and breaker 2 is
either open or out-of-service
OR
870966A1.CDR
AR ZONE 1 EXTEND
FLEXLOGIC OPERAND
AR LO
from autoreclose lockout logic
SHOT COUNT > 0
from autoreclose shot counter logic
AR ENABLED
from autoreclose enable logic
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