GE C70 Instruction Manual page 430

CONTROL ELEMENTS
breaker restrike condition is declared in the corresponding phase and the
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
the condition is bypassed), and
• The current subsequently drops out again
The algorithm is illustrated in the following state machine diagram.
5
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 is picked up by breaker failure or instantaneous overcurrent protection.
The following settings are available for each element.
BREAKER RESTRIKE 1 FUNCTION
— Blocks operation of the breaker restrike detection element.
BRK RSTR 1 BLOCK
BREAKER RESTRIKE 1 SOURCE
assigned.
BREAKER RESTRIKE 1 PICKUP
current.
BREAKER RESTRIKE 1 RESET DELAY
picked up for only 1/8th of the power cycle.
5-264
Figure 5-144: Algorithm illustration of state machine to detect restrike
— Enables and disables operation of the breaker restrike detection element.
— Selects the source of the current for this element. This source must have a valid CT bank
— Specifies the pickup level of the overcurrent detector in per-unit values of CT nominal
— Specifies the reset delay for this element. When set to "0 ms," then FlexLogic operand is
C70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL
operand asserts for a short
BRK RESTRIKE 1 OP
BREAKER RESTRIKE 1 HF DETECT
CHAPTER 5: SETTINGS
setting is Enabled, otherwise