GE B90 - Page 353

CHAPTER 5: SETTINGS GROUPED ELEMENTS
B90 LOW IMPEDANCE BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 5-161
5
The breaker failure feature has two parts: breaker failure current supervision and breaker failure logic. Breaker failure
current supervision acts upon current levels and is available if the
PRODUCT SETUP  B90 FUNCTION  B90 FUNCTION setting
is “Protection.” Breaker failure logic is based on status information and is available if the
PRODUCT SETUP  B90 FUNCTION 
B90 FUNCTION
setting is “Logic.” The Breaker failure element requires B90 fiber optic interconnection and proper
configuration of the breaker failure and direct input/output settings. See the Application of Settings chapter for details.
5.6.4.1 Breaker failure protection
In general, breaker failure schemes expect that the breaker receiving the trip command opens within a set time. If it does
not, upstream or adjacent breakers are tripped to effectively clear the fault. This widespread tripping usually interrupts
power to a larger section of the power system than the initial trip. A higher level of security is required due to the effect on
system safety and stability.
The breaker failure scheme is intended for three-pole operation but can be used with single-pole tripping if certain
conditions are satisfied (see the note below). The operation of the breaker failure element includes three stages: initiation,
identification of a breaker failure condition, and output (or response).

BF1 BKR TEST ON:
Off
Range: FlexLogic operand

BF1 AMP HISET OP A:
Off
Range: FlexLogic operand

BF1 AMP HISET OP B:
Off
Range: FlexLogic operand

BF1 AMP HISET OP C:
Off
Range: FlexLogic operand

BF1 AMP LOSET OP A:
Off
Range: FlexLogic operand

BF1 AMP LOSET OP B:
Off
Range: FlexLogic operand

BF1 AMP LOSET OP C:
Off
Range: FlexLogic operand

BF1 LOSET TIME
DELAY: 0.000 s
Range: 0.000 to 65.535 s in steps of 1

BF1 TRIP DROPOUT
TIME DELAY: 0.000 s
Range: 0.000 to 65.535 s in steps of 1

BF1 RETRIP TIME
DELAY: 0.000 s
Range: 0.000 to 65.535 s in steps of 1

BF1 BLOCK:
Off
Range: FlexLogic operand

BF1 TARGET:
Self-Reset
Range: Self-Reset, Latched, Disabled

BF1 EVENTS:
Disabled
Range: Enabled, Disabled

 BREAKER FAILURE
 CURRENT SUPV 2

 BREAKER FAILURE 2



 BREAKER FAILURE
 CURRENT SUPV 24

 BREAKER FAILURE 24
