GE F60 - Page 405

GE Multilin F60 Feeder Protection System 5-273
5 SETTINGS 5.7 CONTROL ELEMENTS
5
tion is declared in the corresponding phase and the BRK RESTRIKE 1 OP operand is asserted for a short period of time. The
user can add counters and other logic to facilitate the decision making process as to the appropriate actions upon detecting
a single restrike or a series of consecutive restrikes.
A restrike event (FlexLogic operand) is declared if all of the following hold:
• The current is initially interrupted
• The breaker status is open
• An elevated high frequency current condition occurs (if the
BREAKER RESTRIKE 1 HF DETECT setting is Enabled, other-
wise the condition is bypassed), and
• The current subsequently drops out again
The algorithm is illustrated in the state machine diagram shown below.
Figure 5–127: ALGORITHM ILLUSTRATION – STATE MACHINE TO DETECT RESTRIKE
In this way, a distinction is made between a self-extinguishing restrike and permanent breaker failure condition. The latter
can be detected by the breaker failure function or a regular instantaneous overcurrent element. Also, a fast succession of
restrikes will be picked up by breaker failure or instantaneous overcurrent protection.
The following settings are available for each element.
• BREAKER RESTRIKE 1 FUNCTION: This setting enable and disables operation of the breaker restrike detection ele-
ment.
• BRK RSTR 1 BLOCK: This setting is used to block operation of the breaker restrike detection element.
• BREAKER RESTRIKE 1 SOURCE: This setting selects the source of the current for this element. This source must
have a valid CT bank assigned.
• BREAKER RESTRIKE 1 PICKUP: This setting specifies the pickup level of the overcurrent detector in per-unit values
of CT nominal current.
• BREAKER RESTRIKE 1 RESET DELAY: This setting specifies the reset delay for this element. When set to “0 ms”,
then FlexLogic operand will be picked up for only 1/8th of the power cycle.
Capacitor bank
offline
Current
interruption
(overcurrent)
High-frequency
elevated current
(if enabled)
Restrike detected:
OP state asserted
Breaker close
Breaker
close
Breaker
close
Capacitor bank
online
Current
interruption
(overcurrent)
Breaker open
command or breaker
open state
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