GE D90 Plus - Page 354

344 D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CONTROL ELEMENTS CHAPTER 7: PROTECTION
Figure 286: Autoreclose transfer logic
When the 1-2 reclosing sequence is selected and breaker 1 is blocked (the AR BKR1 BLK
operand is set), the reclose signal can be transferred direct to breaker 2 when the
Transfer
1 to 2
setting is “Yes.” When the setting is “No,” the scheme is sent to lockout by the
incomplete sequence timer.
When the 2-1 reclosing sequence is selected and breaker 2 is blocked (the AR BKR2 BLK
operand is set), the reclose signal can be transferred direct to breaker 1 when the
Transfer
2 to 1 setting is “Yes.” If set to “No,” the scheme is sent to lockout by the incomplete
sequence timer or if it is out-of-service or open prior to the reclose-in-progress. In this case,
the scheme can be configured to transfer close command immediately to the second
breaker via the
Transfer 1 to 2 and Transfer 2 to 1 settings.
For two-breaker reclosing on a transient fault, the reset timer is started when the first
reclose output signal is sent to close breaker 1. The CLOSE BREAKER 1 signal initiates the
transfer timer that times out and sends the close signal to the second breaker. If the
reclosure sequence is successful (both breakers closed and there is no initiating signal), the
reset timer times out and returns the scheme to the reset state with the shot counter set to
0. The scheme is now ready for a new reclose cycle.
A typical reclosing sequence for the “1 & 3 Pole” mode is shown below for a single-pole
fault, two shots, with successful reclosure. The following two options are available if the
selected breaker sequence is “1–2” or “2–1,” and the breaker fails to close after the first or
second reclose attempt:
•When the
Breaker 1 Failure Option or Breaker 2 Failure Option is set to “Lockout,” the
scheme goes to lockout state.
•When the
Breaker 1 Failure Option or Breaker 2 Failure Option is set to “Continue,” the
reclose process continues with breaker 2. At the same time, the shot counter is
decreased (since the closing process was not completed).
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