Breaker Failure (Ansi 50Bf) - GE L30 Instruction Manual

CHAPTER 5: SETTINGS
The positive-sequence restraint allows for more sensitive settings by counterbalancing spurious negative-sequence
currents resulting from
• System unbalances under heavy load conditions
• Transformation errors of current transformers (CTs) during three-phase faults
• Fault inception and switch-off transients during three-phase faults
The positive-sequence restraint must be considered when testing for pickup accuracy and response time (multiple of
pickup). The operating quantity depends on how the test currents are injected into the relay (single-phase injection:
I
= 0.2917 x I ; three-phase injection, opposite rotation: I
op injected

5.7.8 Breaker failure (ANSI 50BF)

SETTINGS  GROUPED ELEMENTS  SETTING GROUP 1(6)  BREAKER FAILURE  BREAKER FAILURE 1(2)
 BREAKER FAILURE 1

L30 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
op
Figure 5-109: Negative sequence IOC1 logic
BF1 FUNCTION:

Disabled
BF1 MODE:

3-Pole
BF1 SOURCE:

SRC 1
BF1 USE AMP SUPV:

Yes
BF1 USE SEAL-IN:

Yes
BF1 3-POLE INITIATE:

Off
BF1 BLOCK:

Off
BF1 PH AMP SUPV

PICKUP: 1.050 pu
BF1 N AMP SUPV

PICKUP: 1.050 pu
BF1 USE TIMER 1:

Yes
BF1 TIMER 1 PICKUP

DELAY: 0.000 s
= I ).
injected
Range: Disabled, Enabled
Range: 3-Pole, 1-Pole
Range: SRC 1, SRC 2
Range: Yes, No
Range: Yes, No
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: Yes, No
Range: 0.000 to 65.535 s in steps of 0.001
GROUPED ELEMENTS
5
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