GE b30 Instruction Manual page 357

CHAPTER 5: SETTINGS
In general, a breaker failure scheme determines that a breaker signaled to trip has not cleared a fault within a definite
time, so further tripping action must be performed. Tripping from the breaker failure scheme should trip all breakers, both
local and remote, that can supply current to the faulted zone. Usually operation of a breaker failure element causes
clearing of a larger section of the power system than the initial trip. Because breaker failure can result in tripping a large
number of breakers and this affects system safety and stability, a very high level of security is required.
Two schemes are provided: one for three-pole tripping only (identified by the name "3BF") and one for three pole plus
single-pole operation (identified by the name "1BF"). The philosophy used in these schemes is identical. The operation of a
breaker failure element includes three stages: initiation, determination of a breaker failure condition, and output.
Initiation stage
A FlexLogic operand representing the protection trip signal initially sent to the breaker must be selected to initiate the
scheme. The initiating signal is sealed-in if primary fault detection can reset before the breaker failure timers have finished
timing. The seal-in is supervised by current level, so it is reset when the fault is cleared. If desired, an incomplete sequence
seal-in reset can be implemented by using the initiating operand to also initiate a FlexLogic timer, set longer than any
breaker failure timer, whose output operand is selected to block the breaker failure scheme.
B30 BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
φ
BF1 BKR POS2 A/3P:

Off
BF1 BREAKER TEST ON:

Off
BF1 PH AMP HISET

PICKUP: 1.050 pu
BF1 N AMP HISET

PICKUP: 1.050 pu
BF1 PH AMP LOSET

PICKUP: 1.050 pu
BF1 N AMP LOSET

PICKUP: 1.050 pu
BF1 LOSET TIME

DELAY: 0.000 s
BF1 TRIP DROPOUT

DELAY: 0.000 s
BF1 TARGET:

Self-Reset
BF1 EVENTS:

Disabled
BF1 PH A INITIATE:

Off
BF1 PH B INITIATE:

Off
BF1 PH C INITIATE:

Off
φ
BF1 BKR POS1 B:

Off
φ
BF1 BKR POS1 C:

Off
φ
BF1 BKR POS2 B:

Off
φ
BF1 BKR POS2 C:

Off
GROUPED ELEMENTS
Range: FlexLogic operand
Range: FlexLogic operand
Range: 0.020 to 30.000 pu in steps of 0.001
Range: 0.020 to 30.000 pu in steps of 0.001
Range: 0.020 to 30.000 pu in steps of 0.001
Range: 0.020 to 30.000 pu in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
Range: FlexLogic operand
Valid only for 1-Pole breaker failure schemes
Range: FlexLogic operand
Valid only for 1-Pole breaker failure schemes
Range: FlexLogic operand
Valid only for 1-Pole breaker failure schemes
Range: FlexLogic operand
Valid only for 1-Pole breaker failure schemes
Range: FlexLogic operand
Valid only for 1-Pole breaker failure schemes
Range: FlexLogic operand
Valid only for 1-Pole breaker failure schemes
Range: FlexLogic operand
Valid only for 1-Pole breaker failure schemes
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